diff --git a/packages/localizations/src/en-US.ts b/packages/localizations/src/en-US.ts
index 57803d65415..596f76ecf64 100644
--- a/packages/localizations/src/en-US.ts
+++ b/packages/localizations/src/en-US.ts
@@ -540,6 +540,7 @@ export const enUS: LocalizationResource = {
       detailsTitle__inviteFailed:
         'The invitations could not be sent. There are already pending invitations for the following email addresses: {{email_addresses}}.',
       formButtonPrimary__continue: 'Send invitations',
+      formButtonPrimary__purchaseSeats: 'Purchase additional seats',
       selectDropdown__role: 'Select role',
       subtitle: 'Enter or paste one or more email addresses, separated by spaces or commas.',
       successMessage: 'Invitations successfully sent',
diff --git a/packages/shared/src/types/localization.ts b/packages/shared/src/types/localization.ts
index afafe6dcc5d..aa8c45d5d80 100644
--- a/packages/shared/src/types/localization.ts
+++ b/packages/shared/src/types/localization.ts
@@ -1115,6 +1115,7 @@ export type __internal_LocalizationResource = {
       successMessage: LocalizationValue;
       detailsTitle__inviteFailed: LocalizationValue<'email_addresses'>;
       formButtonPrimary__continue: LocalizationValue;
+      formButtonPrimary__purchaseSeats: LocalizationValue;
       selectDropdown__role: LocalizationValue;
     };
     removeDomainPage: {
diff --git a/packages/ui/src/components/OrganizationProfile/InviteMembersForm.tsx b/packages/ui/src/components/OrganizationProfile/InviteMembersForm.tsx
index 3ec23fc463a..0a8dcc9682d 100644
--- a/packages/ui/src/components/OrganizationProfile/InviteMembersForm.tsx
+++ b/packages/ui/src/components/OrganizationProfile/InviteMembersForm.tsx
@@ -8,6 +8,11 @@ import { useCardState } from '@/ui/elements/contexts';
 import { Form } from '@/ui/elements/Form';
 import { FormButtonContainer } from '@/ui/elements/FormButtons';
 import { TagInput } from '@/ui/elements/TagInput';
+import {
+  getPaidSeatsUnitTier,
+  getSeatUnitPrice,
+  organizationAndInvitationsExceedsPurchasedSeats,
+} from '@/ui/utils/billingPlanSeats';
 import { handleError } from '@/ui/utils/errorHandler';
 import { getClosestProfileScrollBoxFromElement } from '@/ui/utils/getClosestProfileScrollBox';
 import { createListFormat } from '@/ui/utils/passwordUtils';
@@ -39,7 +44,8 @@ export const InviteMembersForm = (props: InviteMembersFormProps) => {
       keepPreviousData: true,
     },
   });
-  const { subscriptionItems } = useSubscription();
+  const { data: subscription, subscriptionItems } = useSubscription();
+  const activeSubscriptionItem = subscription?.subscriptionItems.find(si => si.status === 'active');
   const { handleSelectPlan } = usePlansContext();
   const card = useCardState();
   const { t, locale } = useLocalizations();
@@ -78,6 +84,14 @@ export const InviteMembersForm = (props: InviteMembersFormProps) => {
   } = emailAddressField;
 
   const canSubmit = (!!emailAddressField.value.length || isValidUnsubmittedEmail) && !!roleField.value;
+  const emailAddresses = emailAddressField.value.split(',');
+
+  const seatUnitPrice = activeSubscriptionItem ? getSeatUnitPrice(activeSubscriptionItem.plan) : null;
+  const paidSeatsTier = seatUnitPrice ? getPaidSeatsUnitTier(seatUnitPrice) : null;
+  const isPerSeatCostPlan = !!paidSeatsTier;
+  const mustPurchaseSeats =
+    isPerSeatCostPlan &&
+    organizationAndInvitationsExceedsPurchasedSeats(activeSubscriptionItem, organization, emailAddresses.length);
 
   const onSubmit = async (e: FormEvent<HTMLFormElement>) => {
     e.preventDefault();
@@ -232,7 +246,11 @@ export const InviteMembersForm = (props: InviteMembersFormProps) => {
           <Form.SubmitButton
             block={false}
             isDisabled={!canSubmit}
-            localizationKey={localizationKeys('organizationProfile.invitePage.formButtonPrimary__continue')}
+            localizationKey={
+              isPerSeatCostPlan && mustPurchaseSeats
+                ? localizationKeys('organizationProfile.invitePage.formButtonPrimary__purchaseSeats')
+                : localizationKeys('organizationProfile.invitePage.formButtonPrimary__continue')
+            }
           />
           <Form.ResetButton
             localizationKey={resetButtonLabel || localizationKeys('userProfile.formButtonReset')}
diff --git a/packages/ui/src/utils/__tests__/billingPlanSeats.test.ts b/packages/ui/src/utils/__tests__/billingPlanSeats.test.ts
index 6c6c8321c95..cfe0855da8c 100644
--- a/packages/ui/src/utils/__tests__/billingPlanSeats.test.ts
+++ b/packages/ui/src/utils/__tests__/billingPlanSeats.test.ts
@@ -1,7 +1,19 @@
-import type { BillingMoneyAmount, BillingPaymentTotals, BillingPerUnitTotal } from '@clerk/shared/types';
+import type {
+  BillingMoneyAmount,
+  BillingPaymentTotals,
+  BillingPerUnitTotal,
+  BillingPlanUnitPrice,
+  BillingSubscriptionItemResource,
+  OrganizationResource,
+} from '@clerk/shared/types';
 import { describe, expect, test } from 'vitest';
 
-import { getSeatsPerUnitTotal, summarizeSeatCharges } from '../billingPlanSeats';
+import {
+  getPaidSeatsUnitTier,
+  getSeatsPerUnitTotal,
+  organizationAndInvitationsExceedsPurchasedSeats,
+  summarizeSeatCharges,
+} from '../billingPlanSeats';
 
 const money = (amount: number): BillingMoneyAmount => ({
   amount,
@@ -121,3 +133,67 @@ describe('summarizeSeatCharges', () => {
     expect(summary!.included).toBe(0);
   });
 });
+
+describe('getPaidSeatsUnitTier', () => {
+  test('returns the paid tier from a seats unit price with included seats', () => {
+    const paidTier = {
+      id: 'tier_paid',
+      startsAtBlock: 4,
+      endsAfterBlock: null,
+      feePerBlock: money(500),
+    };
+    const unitPrice: BillingPlanUnitPrice = {
+      name: 'seats',
+      blockSize: 1,
+      tiers: [
+        {
+          id: 'tier_included',
+          startsAtBlock: 1,
+          endsAfterBlock: 3,
+          feePerBlock: money(0),
+        },
+        paidTier,
+      ],
+    };
+
+    expect(getPaidSeatsUnitTier(unitPrice)).toBe(paidTier);
+  });
+});
+
+describe('organizationAndInvitationsExceedsPurchasedSeats', () => {
+  test('returns true when members, pending invitations, and invitations exceed seats entitlements', () => {
+    const subscriptionItem = {
+      seats: { quantity: 4 },
+    } as BillingSubscriptionItemResource;
+    const organization = {
+      membersCount: 2,
+      pendingInvitationsCount: 1,
+    } as OrganizationResource;
+
+    expect(organizationAndInvitationsExceedsPurchasedSeats(subscriptionItem, organization, 2)).toBe(true);
+  });
+
+  test('returns false when members, pending invitations, and invitations equal seats entitlements', () => {
+    const subscriptionItem = {
+      seats: { quantity: 5 },
+    } as BillingSubscriptionItemResource;
+    const organization = {
+      membersCount: 2,
+      pendingInvitationsCount: 1,
+    } as OrganizationResource;
+
+    expect(organizationAndInvitationsExceedsPurchasedSeats(subscriptionItem, organization, 2)).toBe(false);
+  });
+
+  test('returns false when members, pending invitations, and invitations are below seats entitlements', () => {
+    const subscriptionItem = {
+      seats: { quantity: 10 },
+    } as BillingSubscriptionItemResource;
+    const organization = {
+      membersCount: 2,
+      pendingInvitationsCount: 1,
+    } as OrganizationResource;
+
+    expect(organizationAndInvitationsExceedsPurchasedSeats(subscriptionItem, organization, 2)).toBe(false);
+  });
+});
diff --git a/packages/ui/src/utils/billingPlanSeats.ts b/packages/ui/src/utils/billingPlanSeats.ts
index 9c86e016a02..3635e60a851 100644
--- a/packages/ui/src/utils/billingPlanSeats.ts
+++ b/packages/ui/src/utils/billingPlanSeats.ts
@@ -4,6 +4,8 @@ import type {
   BillingPerUnitTotalTier,
   BillingPlanResource,
   BillingPlanUnitPrice,
+  BillingPlanUnitPriceTier,
+  BillingSubscriptionItemResource,
   OrganizationResource,
 } from '@clerk/shared/types';
 
@@ -135,6 +137,26 @@ export const getIncludedSeatsUnitTotalTier = (
   return null;
 };
 
+export const getPaidSeatsUnitTier = (unitPrice: BillingPlanUnitPrice | null): BillingPlanUnitPriceTier | null => {
+  if (!unitPrice) {
+    return null;
+  }
+
+  if (unitPrice.tiers.length === 1 && unitPrice.tiers[0].feePerBlock.amount > 0) {
+    return unitPrice.tiers[0];
+  }
+
+  if (
+    unitPrice.tiers.length === 2 &&
+    unitPrice.tiers[0].feePerBlock.amount === 0 &&
+    unitPrice.tiers[1].feePerBlock.amount > 0
+  ) {
+    return unitPrice.tiers[1];
+  }
+
+  return null;
+};
+
 /**
  * Given a plan, return the seat limit for the plan in seats (not blocks), or `null` if seats are
  * unlimited, or `undefined` if the plan has no seat-based pricing.
@@ -166,6 +188,21 @@ export const organizationExceedsPlanSeatLimit = (
   return organization.membersCount + organization.pendingInvitationsCount > seatLimit;
 };
 
+export const organizationAndInvitationsExceedsPurchasedSeats = (
+  subscriptionItem: BillingSubscriptionItemResource | undefined,
+  organization: OrganizationResource,
+  invitationsCount: number,
+): boolean => {
+  if (!subscriptionItem || !subscriptionItem.seats || !subscriptionItem.seats.quantity) {
+    return false;
+  }
+
+  return (
+    organization.membersCount + organization.pendingInvitationsCount + invitationsCount >
+    subscriptionItem.seats.quantity
+  );
+};
+
 export const isPlanWithPerSeatCosts = (plan: BillingPlanResource): boolean => {
   const seatUnitPrice = getSeatUnitPrice(plan);