diff --git a/EasyPost.Tests/ExceptionsTests/ExceptionsTest.cs b/EasyPost.Tests/ExceptionsTests/ExceptionsTest.cs
index fba43920a..b92e8b304 100644
--- a/EasyPost.Tests/ExceptionsTests/ExceptionsTest.cs
+++ b/EasyPost.Tests/ExceptionsTests/ExceptionsTest.cs
@@ -168,7 +168,7 @@ public void TestExceptionConstructors()
             Assert.Equal(testMessage, invalidObjectError.Message);
 
             InvalidParameterError invalidParameterError = new(testPropertyName);
-            Assert.Equal(string.Format(CultureInfo.InvariantCulture, Constants.ErrorMessages.InvalidParameter, testPropertyName), invalidParameterError.Message);
+            Assert.Equal($"{string.Format(CultureInfo.InvariantCulture, Constants.ErrorMessages.InvalidParameter, testPropertyName)}. ", invalidParameterError.Message);
 
             JsonDeserializationError jsonDeserializationError = new(testType);
             Assert.Equal(string.Format(CultureInfo.InvariantCulture, Constants.ErrorMessages.JsonDeserializationError, testType.FullName), jsonDeserializationError.Message);
diff --git a/EasyPost.Tests/Fixture.cs b/EasyPost.Tests/Fixture.cs
index 1b4a3549b..697f6794f 100644
--- a/EasyPost.Tests/Fixture.cs
+++ b/EasyPost.Tests/Fixture.cs
@@ -230,6 +230,36 @@ internal static ParameterSets.CarrierAccount.Create Create(Dictionary<string, ob
                         RegistrationData = fixture.GetOrNull<Dictionary<string, object?>>("registration_data"),
                     };
                 }
+
+                internal static ParameterSets.CarrierAccount.CreateFedEx CreateFedEx(Dictionary<string, object>? fixture)
+                {
+                    fixture ??= new Dictionary<string, object>();
+
+                    return new ParameterSets.CarrierAccount.CreateFedEx
+                    {
+                        Description = fixture.GetOrNull<string>("description"),
+                        Reference = fixture.GetOrNull<string>("reference"),
+                        Credentials = fixture.GetOrNull<Dictionary<string, object?>>("credentials"),
+                        TestCredentials = fixture.GetOrNull<Dictionary<string, object?>>("test_credentials"),
+                        AccountNumber = "123456789",
+                        CorporateAddressCity = "San Francisco",
+                        CorporateAddressCountryCode = "US",
+                        CorporateAddressPostalCode = "94105",
+                        CorporateAddressState = "CA",
+                        CorporateAddressStreet = "345 California St",
+                        CorporateCompanyName = "EasyPost",
+                        CorporateEmailAddress = "me@example.com",
+                        CorporateFirstName = "Demo",
+                        CorporateLastName = "User",
+                        CorporateJobTitle = "Developer",
+                        CorporatePhoneNumber = "5555555555",
+                        ShippingAddressCity = "San Francisco",
+                        ShippingAddressCountryCode = "US",
+                        ShippingAddressPostalCode = "94105",
+                        ShippingAddressState = "CA",
+                        ShippingAddressStreet = "345 California St",
+                    };
+                }
             }
 
             internal static class CustomsInfo
@@ -618,7 +648,7 @@ internal static ParameterSets.Shipment.Create Create(Dictionary<string, object>?
                         Parcel = Parcels.Create(parcelFixture),
                         CustomsInfo = CustomsInfo.Create(customsInfoFixture),
                         Options = Options(optionsFixture),
-                        CarbonOffset = fixture.GetOrDefault<bool>("carbon_offset"),  // this will always be true or false, never null
+                        CarbonOffset = fixture.GetOrDefault<bool>("carbon_offset"), // this will always be true or false, never null
                         CarrierAccountIds = fixture.GetOrNull<List<string>>("carrier_accounts"),
                         Carrier = fixture.GetOrNull<string>("carrier"),
                         Service = fixture.GetOrNull<string>("service"),
diff --git a/EasyPost.Tests/ParametersTests/ParametersTest.cs b/EasyPost.Tests/ParametersTests/ParametersTest.cs
index a8bff19f0..993ff035b 100644
--- a/EasyPost.Tests/ParametersTests/ParametersTest.cs
+++ b/EasyPost.Tests/ParametersTests/ParametersTest.cs
@@ -106,6 +106,44 @@ public void TestParametersToDictionaryWithSubDictionary()
             Assert.Equal(streetB, addressData["street1"]);
         }
 
+        [Fact]
+        [Testing.Exception]
+        public void TestRequiredAndOptionalParameterValidation()
+        {
+            var parametersWithBothParameterSet = new ParameterSetWithRequiredAndOptionalParameters
+            {
+                RequiredParameter = "required",
+                OptionalParameter = "optional",
+            };
+            // should not throw an exception when serializing to a dictionary
+            parametersWithBothParameterSet.ToDictionary();
+
+            var parametersWithOnlyRequiredParameterSet = new ParameterSetWithRequiredAndOptionalParameters
+            {
+                RequiredParameter = "required",
+            };
+
+            // should not throw an exception when serializing to a dictionary
+            parametersWithOnlyRequiredParameterSet.ToDictionary();
+
+            var parametersWithOnlyOptionalParameterSet = new ParameterSetWithRequiredAndOptionalParameters
+            {
+                OptionalParameter = "optional",
+            };
+
+            // should throw an exception when serializing to a dictionary
+            Assert.Throws<Exceptions.General.MissingParameterError>(() => parametersWithOnlyOptionalParameterSet.ToDictionary());
+        }
+
+        private sealed class ParameterSetWithRequiredAndOptionalParameters : Parameters.BaseParameters
+        {
+            [TopLevelRequestParameter(Necessity.Required, "test", "required")]
+            public string? RequiredParameter { get; set; }
+
+            [TopLevelRequestParameter(Necessity.Optional, "test", "optional")]
+            public string? OptionalParameter { get; set; }
+        }
+
         /// <summary>
         /// This test proves that we can reuse the Addresses.Create parameter object,
         /// with its serialization logic adapting to whether it is a top-level parameter object
@@ -200,7 +238,7 @@ public async Task TestDisallowUsingParameterObjectDictionariesInDictionaryFuncti
                 Street1 = street,
             };
 
-            Dictionary<string, object> dictionary = addressCreationParameters.ToDictionary();  // this method is "internal", so end-users won't have access to it, for reasons seen below
+            Dictionary<string, object> dictionary = addressCreationParameters.ToDictionary(); // this method is "internal", so end-users won't have access to it, for reasons seen below
 
             // At this point, the data has already been wrapped properly by the .ToDictionary() method, and this method expects raw (unwrapped) data
             // This will cause a double-wrapping, sending malformed data to the API
diff --git a/EasyPost.Tests/ServicesTests/WithParameters/CarrierAccountServiceTest.cs b/EasyPost.Tests/ServicesTests/WithParameters/CarrierAccountServiceTest.cs
index 0600ae213..f8506f25c 100644
--- a/EasyPost.Tests/ServicesTests/WithParameters/CarrierAccountServiceTest.cs
+++ b/EasyPost.Tests/ServicesTests/WithParameters/CarrierAccountServiceTest.cs
@@ -1,6 +1,7 @@
 using System.Collections.Generic;
 using System.Threading.Tasks;
 using EasyPost.Exceptions.API;
+using EasyPost.Exceptions.General;
 using EasyPost.Models.API;
 using EasyPost.Tests._Utilities;
 using EasyPost.Tests._Utilities.Attributes;
@@ -57,28 +58,49 @@ public async Task TestCreateWithCustomWorkflow()
             UseVCR("create_with_custom_workflow");
 
             // Carriers like FedEx and UPS should hit the `/carrier_accounts/register` endpoint
-            try
-            {
-                Dictionary<string, object> data = Fixtures.BasicCarrierAccount;
-                data["type"] = "FedexAccount";
-                data["registration_data"] = new Dictionary<string, object>();
+            Dictionary<string, object> data = Fixtures.BasicCarrierAccount;
 
-                Parameters.CarrierAccount.Create parameters = Fixtures.Parameters.CarrierAccounts.Create(data);
+            Parameters.CarrierAccount.Create parameters = Fixtures.Parameters.CarrierAccounts.CreateFedEx(data);
 
+            try
+            {
+                // confirms we can pass in CreateFedEx and CreateUps parameters to the same Create method because they are children of the generic Create class
                 CarrierAccount carrierAccount = await Client.CarrierAccount.Create(parameters);
                 CleanUpAfterTest(carrierAccount.Id);
             }
-            catch (InvalidRequestError e)
+
+            catch (BadRequestError e)
             {
                 // the data we're sending is invalid, we want to check that the API error is because of malformed data and not due to the endpoint
-                Assert.Equal(422, e.StatusCode);  // 422 is fine. We don't want a 404 not found
+                Assert.Equal(400, e.StatusCode); // 400 is fine. We don't want a 404 not found
                 Assert.NotNull(e.Errors);
-                Assert.Contains(e.Errors, error => error is { Field: "account_number", Message: "must be present and a string" });
+                Assert.Contains(e.Errors, error => error is { Message: "Invalid Customer Account Nbr" });
 
                 // Check the cassette to make sure the endpoint is correct (it should be carrier_accounts/register)
+                // Check the cassette to make sure the "registration_data" key is populated in the request body
             }
         }
 
+        [Fact]
+        [CrudOperations.Create]
+        [Testing.Exception]
+        public async Task TestPreventUsersUsingGenericParameterSetWithCustomWorkflow()
+        {
+            UseVCR("prevent_users_using_generic_parameter_set_with_custom_workflow");
+
+            // Generic Create parameter set configured for DHL
+            Dictionary<string, object> data = Fixtures.BasicCarrierAccount;
+
+            // Override the type to be a custom type
+            data["type"] = Constants.CarrierAccountTypes.FedExAccount;
+            data["registration_data"] = new Dictionary<string, object>();
+
+            Parameters.CarrierAccount.Create parameters = Fixtures.Parameters.CarrierAccounts.Create(data);
+
+            // should raise an exception because we're using a generic Create set with a custom workflow type (FedExAccount)
+            await Assert.ThrowsAsync<InvalidParameterError>(async () => await Client.CarrierAccount.Create(parameters));
+        }
+
         [Fact]
         [CrudOperations.Update]
         [Testing.Function]
diff --git a/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/create.json b/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/create.json
index 73722d9a8..2ce8b73f1 100644
--- a/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/create.json
+++ b/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/create.json
@@ -1,7 +1,7 @@
 [
   {
-    "Duration": 495,
-    "RecordedAt": "2023-04-25T21:17:07.055498-06:00",
+    "Duration": 497,
+    "RecordedAt": "2023-08-28T14:42:19.056221-06:00",
     "Request": {
       "Body": "{\"carrier_account\":{\"credentials\":{},\"test_credentials\":{},\"type\":\"DhlEcsAccount\"}}",
       "BodyContentType": "Json",
@@ -17,7 +17,7 @@
       "Uri": "https://api.easypost.com/v2/carrier_accounts"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_861ed435eb4a4507a4c03d28b1ea42f5\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-04-26T03:17:07Z\",\"updated_at\":\"2023-04-26T03:17:07Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_df0f7ebc19d145f2b27140f75e0ae833\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:42:19Z\",\"updated_at\":\"2023-08-28T20:42:19Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Expires": "0",
@@ -32,15 +32,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "Referrer-Policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "d4af614b644897b2e1aa6e3900094645",
+        "x-ep-request-uuid": "72745c0164ed06aaf41dae5800037ea3",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"06d53078d915b2d92cab13769da687ed\"",
-        "x-runtime": "0.107862",
-        "x-node": "bigweb8nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "ETag": "W/\"cf37c4c11197e4344cfbfc0e3f556024\"",
+        "x-runtime": "0.120716",
+        "x-node": "bigweb41nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb1nuq a29e4ad05c,intlb1wdc a29e4ad05c,extlb4wdc a29e4ad05c",
+        "x-proxied": "intlb1nuq 2bcb349163,intlb1wdc 2bcb349163,extlb4wdc 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
@@ -50,8 +50,8 @@
     }
   },
   {
-    "Duration": 305,
-    "RecordedAt": "2023-04-25T21:17:07.371075-06:00",
+    "Duration": 210,
+    "RecordedAt": "2023-08-28T14:42:19.274844-06:00",
     "Request": {
       "Body": "",
       "BodyContentType": "Text",
@@ -61,10 +61,10 @@
         "Authorization": "<REDACTED>",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_861ed435eb4a4507a4c03d28b1ea42f5"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_df0f7ebc19d145f2b27140f75e0ae833"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_861ed435eb4a4507a4c03d28b1ea42f5\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-04-26T03:17:07Z\",\"updated_at\":\"2023-04-26T03:17:07Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_df0f7ebc19d145f2b27140f75e0ae833\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:42:19Z\",\"updated_at\":\"2023-08-28T20:42:19Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Expires": "0",
@@ -79,15 +79,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "Referrer-Policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "d4af614b644897b3e1aa6e3900094661",
+        "x-ep-request-uuid": "72745c0164ed06abf41dae5800037ebf",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"06d53078d915b2d92cab13769da687ed\"",
-        "x-runtime": "0.106327",
-        "x-node": "bigweb2nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "ETag": "W/\"cf37c4c11197e4344cfbfc0e3f556024\"",
+        "x-runtime": "0.029051",
+        "x-node": "bigweb41nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb2nuq a29e4ad05c,intlb1wdc a29e4ad05c,extlb4wdc a29e4ad05c",
+        "x-proxied": "intlb1nuq 2bcb349163,intlb1wdc 2bcb349163,extlb4wdc 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
@@ -97,8 +97,8 @@
     }
   },
   {
-    "Duration": 308,
-    "RecordedAt": "2023-04-25T21:17:07.689754-06:00",
+    "Duration": 397,
+    "RecordedAt": "2023-08-28T14:42:19.679871-06:00",
     "Request": {
       "Body": "",
       "BodyContentType": "Text",
@@ -108,7 +108,7 @@
         "Authorization": "<REDACTED>",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_861ed435eb4a4507a4c03d28b1ea42f5"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_df0f7ebc19d145f2b27140f75e0ae833"
     },
     "Response": {
       "Body": "{}",
@@ -126,15 +126,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "Referrer-Policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "d4af614b644897b3e1aa6e3900094680",
+        "x-ep-request-uuid": "72745c0164ed06abf41dae5800037ed0",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
         "ETag": "W/\"44136fa355b3678a1146ad16f7e8649e\"",
-        "x-runtime": "0.112106",
-        "x-node": "bigweb9nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "x-runtime": "0.212968",
+        "x-node": "bigweb36nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb1nuq a29e4ad05c,intlb2wdc a29e4ad05c,extlb4wdc a29e4ad05c",
+        "x-proxied": "intlb1nuq 2bcb349163,intlb2wdc 2bcb349163,extlb4wdc 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
diff --git a/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/create_with_custom_workflow.json b/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/create_with_custom_workflow.json
index 51bdfbd8b..7bb6621dc 100644
--- a/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/create_with_custom_workflow.json
+++ b/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/create_with_custom_workflow.json
@@ -1,13 +1,13 @@
 [
   {
-    "Duration": 380,
-    "RecordedAt": "2023-04-25T21:17:08.084642-06:00",
+    "Duration": 765,
+    "RecordedAt": "2023-08-28T14:42:20.463087-06:00",
     "Request": {
-      "Body": "{\"carrier_account\":{\"credentials\":{},\"test_credentials\":{},\"type\":\"FedexAccount\",\"registration_data\":{}}}",
+      "Body": "{\"carrier_account\":{\"registration_data\":{\"account_number\":\"123456789\",\"corporate_city\":\"San Francisco\",\"corporate_country_code\":\"US\",\"corporate_postal_code\":\"94105\",\"corporate_state\":\"CA\",\"corporate_streets\":\"345 California St\",\"corporate_company_name\":\"EasyPost\",\"corporate_email_address\":\"me@example.com\",\"corporate_first_name\":\"Demo\",\"corporate_job_title\":\"Developer\",\"corporate_last_name\":\"User\",\"corporate_phone_number\":\"5555555555\",\"shipping_city\":\"San Francisco\",\"shipping_country_code\":\"US\",\"shipping_postal_code\":\"94105\",\"shipping_state\":\"CA\",\"shipping_streets\":\"345 California St\"},\"credentials\":{},\"test_credentials\":{},\"type\":\"FedexAccount\"}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Content-Type": "application/json; charset=utf-8",
-        "Content-Length": "299"
+        "Content-Length": "848"
       },
       "Method": "POST",
       "RequestHeaders": {
@@ -17,12 +17,12 @@
       "Uri": "https://api.easypost.com/v2/carrier_accounts/register"
     },
     "Response": {
-      "Body": "{\"error\":{\"code\":\"UNPROCESSABLE_ENTITY\",\"message\":\"The request was understood, but cannot be processed.\",\"errors\":[{\"field\":\"shipping_streets\",\"message\":\"must be present and a string\"},{\"field\":\"shipping_city\",\"message\":\"must be present and a string\"},{\"field\":\"shipping_state\",\"message\":\"must be present and a string\"},{\"field\":\"shipping_postal_code\",\"message\":\"must be present and a string\"},{\"field\":\"shipping_country_code\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_first_name\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_last_name\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_job_title\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_company_name\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_phone_number\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_email_address\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_streets\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_city\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_state\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_postal_code\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_country_code\",\"message\":\"must be present and a string\"},{\"field\":\"account_number\",\"message\":\"must be present and a string\"}]}}",
+      "Body": "{\"error\":{\"code\":\"BAD_REQUEST\",\"message\":\"Malformed request. Please check the contents and retry.\",\"errors\":[{\"code\":\"3001\",\"message\":\"Invalid Customer Account Nbr\"}]}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Expires": "0",
         "Content-Type": "application/json; charset=utf-8",
-        "Content-Length": "1347"
+        "Content-Length": "168"
       },
       "HttpVersion": "1.1",
       "ResponseHeaders": {
@@ -32,19 +32,19 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "Referrer-Policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "72c23981644897b4e198efc200080b10",
+        "x-ep-request-uuid": "f17fc6ca64ed06acf451c98a000d0953",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "x-runtime": "0.031220",
-        "x-node": "bigweb9nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "x-runtime": "0.358320",
+        "x-node": "bigweb34nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb1nuq a29e4ad05c,intlb1wdc a29e4ad05c,extlb3wdc a29e4ad05c",
+        "x-proxied": "intlb1nuq 2bcb349163,intlb2wdc 2bcb349163,extlb3wdc 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
-        "Code": 422,
-        "Message": "Unprocessable Entity"
+        "Code": 400,
+        "Message": "Bad Request"
       }
     }
   }
diff --git a/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/update.json b/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/update.json
index 6d32ca9d0..19615a4b4 100644
--- a/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/update.json
+++ b/EasyPost.Tests/cassettes/net/carrier_account_service_with_parameters/update.json
@@ -1,7 +1,7 @@
 [
   {
-    "Duration": 553,
-    "RecordedAt": "2023-04-25T21:17:06.023764-06:00",
+    "Duration": 911,
+    "RecordedAt": "2023-08-28T14:42:17.956817-06:00",
     "Request": {
       "Body": "{\"carrier_account\":{\"credentials\":{},\"test_credentials\":{},\"type\":\"DhlEcsAccount\"}}",
       "BodyContentType": "Json",
@@ -17,7 +17,7 @@
       "Uri": "https://api.easypost.com/v2/carrier_accounts"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_2e5389c35758460dbdd8a9c9d0ba6a9a\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-04-26T03:17:06Z\",\"updated_at\":\"2023-04-26T03:17:06Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_4d737e02f8264c628f27c7754a740792\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:42:17Z\",\"updated_at\":\"2023-08-28T20:42:17Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
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@@ -32,15 +32,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "Referrer-Policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "d677fdb5644897b2e1bed1c20008c9b8",
+        "x-ep-request-uuid": "2c07ce3764ed06a9f40a73ac00014f36",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"236205dbbaa0afe97e4b10703e32e089\"",
-        "x-runtime": "0.117437",
-        "x-node": "bigweb1nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "ETag": "W/\"802cd80ec02ee03f5acf69b136a70056\"",
+        "x-runtime": "0.227181",
+        "x-node": "bigweb35nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb2nuq a29e4ad05c,extlb2nuq a29e4ad05c",
+        "x-proxied": "intlb1nuq 2bcb349163,extlb2nuq 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
@@ -50,8 +50,8 @@
     }
   },
   {
-    "Duration": 171,
-    "RecordedAt": "2023-04-25T21:17:06.263734-06:00",
+    "Duration": 164,
+    "RecordedAt": "2023-08-28T14:42:18.177268-06:00",
     "Request": {
       "Body": "{\"carrier_account\":{\"description\":\"my custom description\"}}",
       "BodyContentType": "Json",
@@ -64,10 +64,10 @@
         "Authorization": "<REDACTED>",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_2e5389c35758460dbdd8a9c9d0ba6a9a"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_4d737e02f8264c628f27c7754a740792"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_2e5389c35758460dbdd8a9c9d0ba6a9a\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-04-26T03:17:06Z\",\"updated_at\":\"2023-04-26T03:17:06Z\",\"description\":\"my custom description\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_4d737e02f8264c628f27c7754a740792\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:42:17Z\",\"updated_at\":\"2023-08-28T20:42:18Z\",\"description\":\"my custom description\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
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@@ -82,15 +82,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "Referrer-Policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "d677fdb5644897b2e1bed1c20008c9eb",
+        "x-ep-request-uuid": "2c07ce3764ed06aaf40a73ac00014f54",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"79b8a78a445841c6650f3afcb89ebd04\"",
-        "x-runtime": "0.123185",
-        "x-node": "bigweb4nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "ETag": "W/\"41edc266c3a8fb016b68696d793b93ad\"",
+        "x-runtime": "0.120572",
+        "x-node": "bigweb39nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb1nuq a29e4ad05c,extlb2nuq a29e4ad05c",
+        "x-proxied": "intlb1nuq 2bcb349163,extlb2nuq 003ad9bca0",
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       "Status": {
@@ -100,8 +100,8 @@
     }
   },
   {
-    "Duration": 78,
-    "RecordedAt": "2023-04-25T21:17:06.382304-06:00",
+    "Duration": 74,
+    "RecordedAt": "2023-08-28T14:42:18.288989-06:00",
     "Request": {
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       "BodyContentType": "Text",
@@ -111,10 +111,10 @@
         "Authorization": "<REDACTED>",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_2e5389c35758460dbdd8a9c9d0ba6a9a"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_4d737e02f8264c628f27c7754a740792"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_2e5389c35758460dbdd8a9c9d0ba6a9a\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-04-26T03:17:06Z\",\"updated_at\":\"2023-04-26T03:17:06Z\",\"description\":\"my custom description\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_4d737e02f8264c628f27c7754a740792\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:42:17Z\",\"updated_at\":\"2023-08-28T20:42:18Z\",\"description\":\"my custom description\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
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@@ -129,15 +129,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "Referrer-Policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "d677fdb5644897b2e1bed1c20008ca09",
+        "x-ep-request-uuid": "2c07ce3764ed06aaf40a73ac00014f67",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"79b8a78a445841c6650f3afcb89ebd04\"",
-        "x-runtime": "0.027493",
-        "x-node": "bigweb4nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "ETag": "W/\"41edc266c3a8fb016b68696d793b93ad\"",
+        "x-runtime": "0.028372",
+        "x-node": "bigweb41nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb2nuq a29e4ad05c,extlb2nuq a29e4ad05c",
+        "x-proxied": "intlb1nuq 2bcb349163,extlb2nuq 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
@@ -147,8 +147,8 @@
     }
   },
   {
-    "Duration": 157,
-    "RecordedAt": "2023-04-25T21:17:06.547797-06:00",
+    "Duration": 236,
+    "RecordedAt": "2023-08-28T14:42:18.53858-06:00",
     "Request": {
       "Body": "",
       "BodyContentType": "Text",
@@ -158,7 +158,7 @@
         "Authorization": "<REDACTED>",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_2e5389c35758460dbdd8a9c9d0ba6a9a"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_4d737e02f8264c628f27c7754a740792"
     },
     "Response": {
       "Body": "{}",
@@ -176,15 +176,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "Referrer-Policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "d677fdb5644897b2e1bed1c20008ca17",
+        "x-ep-request-uuid": "2c07ce3764ed06aaf40a73ac00014f6c",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
         "ETag": "W/\"44136fa355b3678a1146ad16f7e8649e\"",
-        "x-runtime": "0.117694",
-        "x-node": "bigweb8nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "x-runtime": "0.195496",
+        "x-node": "bigweb38nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb2nuq a29e4ad05c,extlb2nuq a29e4ad05c",
+        "x-proxied": "intlb2nuq 2bcb349163,extlb2nuq 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
diff --git a/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/create.json b/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/create.json
index a48f1067a..ae0347e7b 100644
--- a/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/create.json
+++ b/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/create.json
@@ -1,7 +1,7 @@
 [
   {
-    "Duration": 487,
-    "RecordedAt": "2023-03-15T16:18:03.712177-06:00",
+    "Duration": 466,
+    "RecordedAt": "2023-08-28T14:48:55.287183-06:00",
     "Request": {
       "Body": "{\"carrier_account\":{\"credentials\":{},\"test_credentials\":{},\"type\":\"DhlEcsAccount\"}}",
       "BodyContentType": "Json",
@@ -12,14 +12,12 @@
       "Method": "POST",
       "RequestHeaders": {
         "Authorization": "<REDACTED>",
-        "content_type": "application/json",
-        "Accept": "application/json,text/json,text/x-json,text/javascript,application/xml,text/xml",
         "User-Agent": "<REDACTED>"
       },
       "Uri": "https://api.easypost.com/v2/carrier_accounts"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_f54473759d1e46cfb4957b0ab8beef1a\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-03-15T22:18:03Z\",\"updated_at\":\"2023-03-15T22:18:03Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_68f5d528b6604cc8ad511b7ecac0e55a\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:48:55Z\",\"updated_at\":\"2023-08-28T20:48:55Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Expires": "0",
@@ -34,15 +32,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "referrer-policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "f46ccd146412441be660bbe900050c93",
+        "x-ep-request-uuid": "f17fc6cf64ed0837f450a4f1000d8d77",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"e5b846917019f11e3dd483dcd6fe896e\"",
-        "x-runtime": "0.121496",
-        "x-node": "bigweb4nuq",
-        "x-version-label": "easypost-202303142258-f5b873fcbd-master",
+        "ETag": "W/\"1a5051d8d6c18a69399dda03600a9a14\"",
+        "x-runtime": "0.106863",
+        "x-node": "bigweb41nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb2nuq a40ea751fd,intlb1wdc a40ea751fd,extlb3wdc a40ea751fd",
+        "x-proxied": "intlb1nuq 2bcb349163,intlb1wdc 2bcb349163,extlb3wdc 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
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       "Status": {
@@ -52,8 +50,8 @@
     }
   },
   {
-    "Duration": 236,
-    "RecordedAt": "2023-03-15T16:18:03.976893-06:00",
+    "Duration": 306,
+    "RecordedAt": "2023-08-28T14:48:55.608275-06:00",
     "Request": {
       "Body": "",
       "BodyContentType": "Text",
@@ -61,14 +59,12 @@
       "Method": "GET",
       "RequestHeaders": {
         "Authorization": "<REDACTED>",
-        "content_type": "application/json",
-        "Accept": "application/json,text/json,text/x-json,text/javascript,application/xml,text/xml",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_f54473759d1e46cfb4957b0ab8beef1a"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_68f5d528b6604cc8ad511b7ecac0e55a"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_f54473759d1e46cfb4957b0ab8beef1a\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-03-15T22:18:03Z\",\"updated_at\":\"2023-03-15T22:18:03Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_68f5d528b6604cc8ad511b7ecac0e55a\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:48:55Z\",\"updated_at\":\"2023-08-28T20:48:55Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Expires": "0",
@@ -83,15 +79,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "referrer-policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "f46ccd146412441be660bbe900050cb6",
+        "x-ep-request-uuid": "f17fc6cf64ed0837f450a4f1000d8d9a",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"e5b846917019f11e3dd483dcd6fe896e\"",
-        "x-runtime": "0.038347",
-        "x-node": "bigweb5nuq",
-        "x-version-label": "easypost-202303142258-f5b873fcbd-master",
+        "ETag": "W/\"1a5051d8d6c18a69399dda03600a9a14\"",
+        "x-runtime": "0.120709",
+        "x-node": "bigweb40nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb1nuq a40ea751fd,intlb1wdc a40ea751fd,extlb3wdc a40ea751fd",
+        "x-proxied": "intlb1nuq 2bcb349163,intlb1wdc 2bcb349163,extlb3wdc 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
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       "Status": {
@@ -101,8 +97,8 @@
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   {
-    "Duration": 318,
-    "RecordedAt": "2023-03-15T16:18:04.308925-06:00",
+    "Duration": 295,
+    "RecordedAt": "2023-08-28T14:48:55.916517-06:00",
     "Request": {
       "Body": "",
       "BodyContentType": "Text",
@@ -110,11 +106,9 @@
       "Method": "DELETE",
       "RequestHeaders": {
         "Authorization": "<REDACTED>",
-        "content_type": "application/json",
-        "Accept": "application/json,text/json,text/x-json,text/javascript,application/xml,text/xml",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_f54473759d1e46cfb4957b0ab8beef1a"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_68f5d528b6604cc8ad511b7ecac0e55a"
     },
     "Response": {
       "Body": "{}",
@@ -132,15 +126,15 @@
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         "x-permitted-cross-domain-policies": "none",
         "referrer-policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "f46ccd146412441ce660bbe900050cc8",
+        "x-ep-request-uuid": "f17fc6cf64ed0837f450a4f1000d8dbc",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
         "ETag": "W/\"44136fa355b3678a1146ad16f7e8649e\"",
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-        "x-node": "bigweb9nuq",
-        "x-version-label": "easypost-202303142258-f5b873fcbd-master",
+        "x-runtime": "0.118070",
+        "x-node": "bigweb33nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
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-        "x-proxied": "intlb2nuq a40ea751fd,intlb2wdc a40ea751fd,extlb3wdc a40ea751fd",
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diff --git a/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/create_with_custom_workflow.json b/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/create_with_custom_workflow.json
index 70e570ed3..efe40e6fa 100644
--- a/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/create_with_custom_workflow.json
+++ b/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/create_with_custom_workflow.json
@@ -1,30 +1,28 @@
 [
   {
-    "Duration": 295,
-    "RecordedAt": "2023-03-15T16:18:04.621405-06:00",
+    "Duration": 714,
+    "RecordedAt": "2023-08-28T14:45:51.457537-06:00",
     "Request": {
-      "Body": "{\"carrier_account\":{\"credentials\":{},\"test_credentials\":{},\"type\":\"FedexAccount\",\"registration_data\":{}}}",
+      "Body": "{\"carrier_account\":{\"registration_data\":{\"account_number\":\"123456789\",\"corporate_city\":\"San Francisco\",\"corporate_country_code\":\"US\",\"corporate_postal_code\":\"94105\",\"corporate_state\":\"CA\",\"corporate_streets\":\"345 California St\",\"corporate_company_name\":\"EasyPost\",\"corporate_email_address\":\"me@example.com\",\"corporate_first_name\":\"Demo\",\"corporate_job_title\":\"Developer\",\"corporate_last_name\":\"User\",\"corporate_phone_number\":\"5555555555\",\"shipping_city\":\"San Francisco\",\"shipping_country_code\":\"US\",\"shipping_postal_code\":\"94105\",\"shipping_state\":\"CA\",\"shipping_streets\":\"345 California St\"},\"credentials\":{},\"test_credentials\":{},\"type\":\"FedexAccount\"}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Content-Type": "application/json; charset=utf-8",
-        "Content-Length": "299"
+        "Content-Length": "848"
       },
       "Method": "POST",
       "RequestHeaders": {
         "Authorization": "<REDACTED>",
-        "content_type": "application/json",
-        "Accept": "application/json,text/json,text/x-json,text/javascript,application/xml,text/xml",
         "User-Agent": "<REDACTED>"
       },
       "Uri": "https://api.easypost.com/v2/carrier_accounts/register"
     },
     "Response": {
-      "Body": "{\"error\":{\"code\":\"UNPROCESSABLE_ENTITY\",\"message\":\"The request was understood, but cannot be processed.\",\"errors\":[{\"field\":\"shipping_streets\",\"message\":\"must be present and a string\"},{\"field\":\"shipping_city\",\"message\":\"must be present and a string\"},{\"field\":\"shipping_state\",\"message\":\"must be present and a string\"},{\"field\":\"shipping_postal_code\",\"message\":\"must be present and a string\"},{\"field\":\"shipping_country_code\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_first_name\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_last_name\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_job_title\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_company_name\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_phone_number\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_email_address\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_streets\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_city\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_state\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_postal_code\",\"message\":\"must be present and a string\"},{\"field\":\"corporate_country_code\",\"message\":\"must be present and a string\"},{\"field\":\"account_number\",\"message\":\"must be present and a string\"}]}}",
+      "Body": "{\"error\":{\"code\":\"BAD_REQUEST\",\"message\":\"Malformed request. Please check the contents and retry.\",\"errors\":[{\"code\":\"3001\",\"message\":\"Invalid Customer Account Nbr\"}]}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Expires": "0",
         "Content-Type": "application/json; charset=utf-8",
-        "Content-Length": "1347"
+        "Content-Length": "168"
       },
       "HttpVersion": "1.1",
       "ResponseHeaders": {
@@ -34,19 +32,19 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "referrer-policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "287eb8e96412441ce6871586002c370e",
+        "x-ep-request-uuid": "2c07ce3864ed077ff3fa002d00019b39",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "x-runtime": "0.125676",
-        "x-node": "bigweb4nuq",
-        "x-version-label": "easypost-202303142258-f5b873fcbd-master",
+        "x-runtime": "0.327908",
+        "x-node": "bigweb39nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb1nuq a40ea751fd,extlb1nuq a40ea751fd",
+        "x-proxied": "intlb1nuq 2bcb349163,extlb2nuq 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
-        "Code": 422,
-        "Message": "Unprocessable Entity"
+        "Code": 400,
+        "Message": "Bad Request"
       }
     }
   }
diff --git a/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/update.json b/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/update.json
index c8c74d187..b9578f43e 100644
--- a/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/update.json
+++ b/EasyPost.Tests/cassettes/netstandard/carrier_account_service_with_parameters/update.json
@@ -1,7 +1,7 @@
 [
   {
-    "Duration": 485,
-    "RecordedAt": "2023-04-26T10:44:59.86298-06:00",
+    "Duration": 467,
+    "RecordedAt": "2023-08-28T14:48:54.162377-06:00",
     "Request": {
       "Body": "{\"carrier_account\":{\"credentials\":{},\"test_credentials\":{},\"type\":\"DhlEcsAccount\"}}",
       "BodyContentType": "Json",
@@ -17,7 +17,7 @@
       "Uri": "https://api.easypost.com/v2/carrier_accounts"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_b975625f21134c2f96f8eb829d0e98d6\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-04-26T16:44:59Z\",\"updated_at\":\"2023-04-26T16:44:59Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_b9f082277aad4056b80c72b1172f7f0b\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:48:54Z\",\"updated_at\":\"2023-08-28T20:48:54Z\",\"description\":\"DHL eCommerce Solutions Account\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Expires": "0",
@@ -32,15 +32,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "referrer-policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "46503e086449550be186db200016c4cb",
+        "x-ep-request-uuid": "80ef0aca64ed0836f41d14aa000385ff",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"76f95f23220586e51839eedcc9cb6ff5\"",
-        "x-runtime": "0.112891",
-        "x-node": "bigweb5nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "ETag": "W/\"a48b2a039c3b7281931e4eb0a4f60e62\"",
+        "x-runtime": "0.108200",
+        "x-node": "bigweb33nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb2nuq a29e4ad05c,intlb1wdc a29e4ad05c,extlb4wdc a29e4ad05c",
+        "x-proxied": "intlb1nuq 2bcb349163,extlb1nuq 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
@@ -50,8 +50,8 @@
     }
   },
   {
-    "Duration": 327,
-    "RecordedAt": "2023-04-26T10:45:00.207311-06:00",
+    "Duration": 173,
+    "RecordedAt": "2023-08-28T14:48:54.388926-06:00",
     "Request": {
       "Body": "{\"carrier_account\":{\"description\":\"my custom description\"}}",
       "BodyContentType": "Json",
@@ -64,10 +64,10 @@
         "Authorization": "<REDACTED>",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_b975625f21134c2f96f8eb829d0e98d6"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_b9f082277aad4056b80c72b1172f7f0b"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_b975625f21134c2f96f8eb829d0e98d6\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-04-26T16:44:59Z\",\"updated_at\":\"2023-04-26T16:45:00Z\",\"description\":\"my custom description\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_b9f082277aad4056b80c72b1172f7f0b\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:48:54Z\",\"updated_at\":\"2023-08-28T20:48:54Z\",\"description\":\"my custom description\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Expires": "0",
@@ -82,15 +82,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "referrer-policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "46503e086449550be186db200016c4f5",
+        "x-ep-request-uuid": "80ef0aca64ed0836f41d14aa0003861b",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"5a9f42d41b6b5e3df4fb79d47b87aaa3\"",
-        "x-runtime": "0.132030",
-        "x-node": "bigweb11nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "ETag": "W/\"2ac4055abc3fcb44e19df9d046ca86d5\"",
+        "x-runtime": "0.130887",
+        "x-node": "bigweb35nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb2nuq a29e4ad05c,intlb2wdc a29e4ad05c,extlb4wdc a29e4ad05c",
+        "x-proxied": "intlb1nuq 2bcb349163,extlb1nuq 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
@@ -100,8 +100,8 @@
     }
   },
   {
-    "Duration": 208,
-    "RecordedAt": "2023-04-26T10:45:00.428935-06:00",
+    "Duration": 68,
+    "RecordedAt": "2023-08-28T14:48:54.497532-06:00",
     "Request": {
       "Body": "",
       "BodyContentType": "Text",
@@ -111,10 +111,10 @@
         "Authorization": "<REDACTED>",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_b975625f21134c2f96f8eb829d0e98d6"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_b9f082277aad4056b80c72b1172f7f0b"
     },
     "Response": {
-      "Body": "{\"id\":\"ca_b975625f21134c2f96f8eb829d0e98d6\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-04-26T16:44:59Z\",\"updated_at\":\"2023-04-26T16:45:00Z\",\"description\":\"my custom description\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
+      "Body": "{\"id\":\"ca_b9f082277aad4056b80c72b1172f7f0b\",\"object\":\"CarrierAccount\",\"type\":\"DhlEcsAccount\",\"clone\":false,\"created_at\":\"2023-08-28T20:48:54Z\",\"updated_at\":\"2023-08-28T20:48:54Z\",\"description\":\"my custom description\",\"reference\":null,\"billing_type\":\"carrier\",\"readable\":\"DHL eCommerce Solutions\",\"logo\":null,\"fields\":{\"credentials\":{},\"test_credentials\":{}},\"credentials\":{},\"test_credentials\":{}}",
       "BodyContentType": "Json",
       "ContentHeaders": {
         "Expires": "0",
@@ -129,15 +129,15 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "referrer-policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "46503e086449550ce186db200016c511",
+        "x-ep-request-uuid": "80ef0aca64ed0836f41d14aa0003863b",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
-        "ETag": "W/\"5a9f42d41b6b5e3df4fb79d47b87aaa3\"",
-        "x-runtime": "0.025453",
-        "x-node": "bigweb11nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "ETag": "W/\"2ac4055abc3fcb44e19df9d046ca86d5\"",
+        "x-runtime": "0.027299",
+        "x-node": "bigweb41nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb2nuq a29e4ad05c,intlb2wdc a29e4ad05c,extlb4wdc a29e4ad05c",
+        "x-proxied": "intlb2nuq 2bcb349163,extlb1nuq 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
@@ -147,8 +147,8 @@
     }
   },
   {
-    "Duration": 304,
-    "RecordedAt": "2023-04-26T10:45:00.744508-06:00",
+    "Duration": 278,
+    "RecordedAt": "2023-08-28T14:48:54.795368-06:00",
     "Request": {
       "Body": "",
       "BodyContentType": "Text",
@@ -158,7 +158,7 @@
         "Authorization": "<REDACTED>",
         "User-Agent": "<REDACTED>"
       },
-      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_b975625f21134c2f96f8eb829d0e98d6"
+      "Uri": "https://api.easypost.com/v2/carrier_accounts/ca_b9f082277aad4056b80c72b1172f7f0b"
     },
     "Response": {
       "Body": "{}",
@@ -176,15 +176,16 @@
         "x-download-options": "noopen",
         "x-permitted-cross-domain-policies": "none",
         "referrer-policy": "strict-origin-when-cross-origin",
-        "x-ep-request-uuid": "46503e086449550ce186db200016c527",
+        "x-ep-request-uuid": "80ef0aca64ed0836f41d14aa00038647",
         "Cache-Control": "no-store, no-cache, private",
         "Pragma": "no-cache",
         "ETag": "W/\"44136fa355b3678a1146ad16f7e8649e\"",
-        "x-runtime": "0.117254",
-        "x-node": "bigweb5nuq",
-        "x-version-label": "easypost-202304252326-79950b6035-master",
+        "x-runtime": "0.235367",
+        "x-node": "bigweb32nuq",
+        "x-version-label": "easypost-202308252358-79b9940f30-master",
         "x-backend": "easypost",
-        "x-proxied": "intlb2nuq a29e4ad05c,intlb2wdc a29e4ad05c,extlb4wdc a29e4ad05c",
+        "x-canary": "direct",
+        "x-proxied": "intlb2nuq 2bcb349163,extlb1nuq 003ad9bca0",
         "Strict-Transport-Security": "max-age=31536000; includeSubDomains; preload"
       },
       "Status": {
diff --git a/EasyPost/Constants.cs b/EasyPost/Constants.cs
index cfad4118a..e89882412 100644
--- a/EasyPost/Constants.cs
+++ b/EasyPost/Constants.cs
@@ -119,13 +119,17 @@ public static class ErrorMessages
         /// </summary>
         public static class CarrierAccountTypes
         {
+            public const string FedExAccount = "FedexAccount";
+
+            public const string UpsAccount = "UpsAccount";
+
             /// <summary>
             ///     Carrier account types that support custom workflows.
             /// </summary>
             internal static List<string> CarrierTypesWithCustomWorkflows => new()
             {
-                "FedexAccount",
-                "UpsAccount",
+                FedExAccount,
+                UpsAccount,
             };
         }
     }
diff --git a/EasyPost/Exceptions/General/InvalidParameterError.cs b/EasyPost/Exceptions/General/InvalidParameterError.cs
index 86d103b21..131f6c788 100644
--- a/EasyPost/Exceptions/General/InvalidParameterError.cs
+++ b/EasyPost/Exceptions/General/InvalidParameterError.cs
@@ -11,8 +11,9 @@ public class InvalidParameterError : ValidationError
         ///     Initializes a new instance of the <see cref="InvalidParameterError" /> class.
         /// </summary>
         /// <param name="parameterName">The name of the invalid parameter.</param>
-        internal InvalidParameterError(string parameterName)
-            : base(string.Format(CultureInfo.InvariantCulture, Constants.ErrorMessages.InvalidParameter, parameterName))
+        /// <param name="followUpMessage">Additional message to include in error message.</param>
+        internal InvalidParameterError(string parameterName, string? followUpMessage = "")
+            : base($"{string.Format(CultureInfo.InvariantCulture, Constants.ErrorMessages.InvalidParameter, parameterName)}. {followUpMessage}")
         {
         }
     }
diff --git a/EasyPost/Parameters/CarrierAccount/CreateFedEx.cs b/EasyPost/Parameters/CarrierAccount/CreateFedEx.cs
new file mode 100644
index 000000000..ce639cc58
--- /dev/null
+++ b/EasyPost/Parameters/CarrierAccount/CreateFedEx.cs
@@ -0,0 +1,75 @@
+using System.Diagnostics.CodeAnalysis;
+using EasyPost.Utilities.Internal.Attributes;
+
+namespace EasyPost.Parameters.CarrierAccount
+{
+    /// <summary>
+    ///     <a href="https://www.easypost.com/docs/api#create-a-carrier-account">Parameters</a> for <see cref="EasyPost.Services.CarrierAccountService.Create(Create, System.Threading.CancellationToken)"/> API calls.
+    /// </summary>
+    [ExcludeFromCodeCoverage]
+    public class CreateFedEx : Create
+    {
+        #region Request Parameters
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "account_number")]
+        public string? AccountNumber { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_city")]
+        public string? CorporateAddressCity { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_country_code")]
+        public string? CorporateAddressCountryCode { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_postal_code")]
+        public string? CorporateAddressPostalCode { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_state")]
+        public string? CorporateAddressState { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_streets")]
+        public string? CorporateAddressStreet { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_company_name")]
+        public string? CorporateCompanyName { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_email_address")]
+        public string? CorporateEmailAddress { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_first_name")]
+        public string? CorporateFirstName { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_job_title")]
+        public string? CorporateJobTitle { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_last_name")]
+        public string? CorporateLastName { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "corporate_phone_number")]
+        public string? CorporatePhoneNumber { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "shipping_city")]
+        public string? ShippingAddressCity { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "shipping_country_code")]
+        public string? ShippingAddressCountryCode { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "shipping_postal_code")]
+        public string? ShippingAddressPostalCode { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "shipping_state")]
+        public string? ShippingAddressState { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "shipping_streets")]
+        public string? ShippingAddressStreet { get; set; }
+
+        #endregion
+
+        /// <summary>
+        ///     Construct a new set of <see cref="CreateFedEx"/> parameters.
+        /// </summary>
+        public CreateFedEx()
+        {
+            Type = Constants.CarrierAccountTypes.FedExAccount;
+        }
+    }
+}
diff --git a/EasyPost/Parameters/CarrierAccount/CreateUps.cs b/EasyPost/Parameters/CarrierAccount/CreateUps.cs
new file mode 100644
index 000000000..d5b0f115a
--- /dev/null
+++ b/EasyPost/Parameters/CarrierAccount/CreateUps.cs
@@ -0,0 +1,78 @@
+using System.Diagnostics.CodeAnalysis;
+using EasyPost.Utilities.Internal.Attributes;
+
+namespace EasyPost.Parameters.CarrierAccount
+{
+    /// <summary>
+    ///     <a href="https://www.easypost.com/docs/api#create-a-carrier-account">Parameters</a> for <see cref="EasyPost.Services.CarrierAccountService.Create(Create, System.Threading.CancellationToken)"/> API calls.
+    /// </summary>
+    [ExcludeFromCodeCoverage]
+    public class CreateUps : Create
+    {
+        #region Request Parameters
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "account_number")]
+        public string? AccountNumber { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "city")]
+        public string? City { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "company")]
+        public string? CompanyName { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "country")]
+        public string? Country { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "email")]
+        public string? Email { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Optional, "carrier_account", "registration_data", "invoice_amount")]
+        public string? InvoiceAmount { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Optional, "carrier_account", "registration_data", "invoice_control_id")]
+        public string? InvoiceControlId { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Optional, "carrier_account", "registration_data", "invoice_currency")]
+        public string? InvoiceCurrency { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Optional, "carrier_account", "registration_data", "invoice_date")]
+        public string? InvoiceDate { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Optional, "carrier_account", "registration_data", "invoice_number")]
+        public string? InvoiceNumber { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "phone")]
+        public string? PhoneNumber { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "postal_code")]
+        public string? PostalCode { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "title")]
+        public string? RegistrarJobTitle { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "name")]
+        public string? RegistrarName { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "state")]
+        public string? State { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "street1")]
+        public string? Street { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Optional, "carrier_account", "registration_data", "street2")]
+        public string? Street2 { get; set; }
+
+        [TopLevelRequestParameter(Necessity.Required, "carrier_account", "registration_data", "website")]
+        public string? Website { get; set; }
+
+        #endregion
+
+        /// <summary>
+        ///     Construct a new set of <see cref="CreateUps"/> parameters.
+        /// </summary>
+        public CreateUps()
+        {
+            Type = Constants.CarrierAccountTypes.UpsAccount;
+        }
+    }
+}
diff --git a/EasyPost/Services/CarrierAccountService.cs b/EasyPost/Services/CarrierAccountService.cs
index bbd70e365..82b8ce180 100644
--- a/EasyPost/Services/CarrierAccountService.cs
+++ b/EasyPost/Services/CarrierAccountService.cs
@@ -68,6 +68,12 @@ public async Task<CarrierAccount> Create(Parameters.CarrierAccount.Create parame
                 throw new MissingParameterError(nameof(parameters.Type));
             }
 
+            // stop the user from using a generic Create parameter set when creating a carrier account with a custom workflow (e.g. FedExAccount)
+            if (parameters.GetType() == typeof(Parameters.CarrierAccount.Create) && Constants.CarrierAccountTypes.CarrierTypesWithCustomWorkflows.Contains(parameters.Type))
+            {
+                throw new InvalidParameterError("parameters", $"Use a {parameters.Type} custom workflow parameter set instead.");
+            }
+
             string endpoint = SelectCarrierAccountCreationEndpoint(parameters.Type);
 
             return await RequestAsync<CarrierAccount>(Method.Post, endpoint, cancellationToken, parameters.ToDictionary());