diff --git a/src/resources/customers/costs.ts b/src/resources/customers/costs.ts
index 0b81cfd0..84339d0b 100644
--- a/src/resources/customers/costs.ts
+++ b/src/resources/customers/costs.ts
@@ -880,12 +880,12 @@ export interface CostListParams {
   /**
    * Costs returned are exclusive of `timeframe_end`.
    */
-  timeframe_end?: string | null;
+  timeframe_end?: string;
 
   /**
    * Costs returned are inclusive of `timeframe_start`.
    */
-  timeframe_start?: string | null;
+  timeframe_start?: string;
 
   /**
    * Controls whether Orb returns cumulative costs since the start of the billing
@@ -900,12 +900,12 @@ export interface CostListByExternalIDParams {
   /**
    * Costs returned are exclusive of `timeframe_end`.
    */
-  timeframe_end?: string | null;
+  timeframe_end?: string;
 
   /**
    * Costs returned are inclusive of `timeframe_start`.
    */
-  timeframe_start?: string | null;
+  timeframe_start?: string;
 
   /**
    * Controls whether Orb returns cumulative costs since the start of the billing
diff --git a/src/resources/subscriptions.ts b/src/resources/subscriptions.ts
index 45b55706..7a4660dc 100644
--- a/src/resources/subscriptions.ts
+++ b/src/resources/subscriptions.ts
@@ -3154,12 +3154,12 @@ export interface SubscriptionFetchCostsParams {
   /**
    * Costs returned are exclusive of `timeframe_end`.
    */
-  timeframe_end?: string | null;
+  timeframe_end?: string;
 
   /**
    * Costs returned are inclusive of `timeframe_start`.
    */
-  timeframe_start?: string | null;
+  timeframe_start?: string;
 
   /**
    * Controls whether Orb returns cumulative costs since the start of the billing