diff --git a/src/client/features/onboarding/OnboardingChatConversation.tsx b/src/client/features/onboarding/OnboardingChatConversation.tsx
index 04eb04f..248fa0f 100644
--- a/src/client/features/onboarding/OnboardingChatConversation.tsx
+++ b/src/client/features/onboarding/OnboardingChatConversation.tsx
@@ -11,7 +11,10 @@ import { useStickToBottom } from "@/client/components/chat/useStickToBottom";
 import { captureClientEvent } from "@/client/lib/posthog";
 import { getStandardErrorMessage } from "@/client/lib/error-messages";
 import { buildCheckoutSuccessUrl } from "@/client/features/billing/checkout-url";
-import { AUTUMN_PAID_PLAN_ID } from "@/shared/billing";
+import {
+  AUTUMN_CHECKOUT_SESSION_PARAMS,
+  AUTUMN_PAID_PLAN_ID,
+} from "@/shared/billing";
 import { FREE_ONBOARDING_QUESTION_LIMIT } from "@/shared/onboardingChat";
 import {
   ChatComposer,
@@ -131,6 +134,7 @@ export function OnboardingChatConversation({
         planId: AUTUMN_PAID_PLAN_ID,
         redirectMode: "always",
         successUrl: buildCheckoutSuccessUrl("/onboarding?step=3"),
+        checkoutSessionParams: AUTUMN_CHECKOUT_SESSION_PARAMS,
       });
     } catch (checkoutErr) {
       setCheckoutError(
diff --git a/src/routes/_app/billing.tsx b/src/routes/_app/billing.tsx
index 2b3699f..d64c0d4 100644
--- a/src/routes/_app/billing.tsx
+++ b/src/routes/_app/billing.tsx
@@ -13,6 +13,7 @@ import { parseTopUpAmount } from "@/client/features/billing/HostedBillingContent
 import { getBillingRouteState } from "@/client/features/billing/route-state";
 import { getCustomerPlanStatus } from "@/client/features/billing/plan-detection";
 import {
+  AUTUMN_CHECKOUT_SESSION_PARAMS,
   AUTUMN_PAID_PLAN_ID,
   BILLING_ROUTE,
   AUTUMN_SEO_DATA_BALANCE_FEATURE_ID,
@@ -103,6 +104,7 @@ function BillingPage() {
       planId: AUTUMN_PAID_PLAN_ID,
       redirectMode: "always",
       successUrl: buildCheckoutSuccessUrl(BILLING_ROUTE),
+      checkoutSessionParams: AUTUMN_CHECKOUT_SESSION_PARAMS,
     });
   }
 
@@ -282,6 +284,7 @@ function BillingPage() {
                       planId: AUTUMN_SEO_DATA_TOP_UP_PLAN_ID,
                       redirectMode: "always",
                       successUrl: window.location.href,
+                      checkoutSessionParams: AUTUMN_CHECKOUT_SESSION_PARAMS,
                       featureQuantities: [
                         {
                           featureId: AUTUMN_SEO_DATA_TOPUP_BALANCE_FEATURE_ID,
diff --git a/src/routes/_authenticated.subscribe.tsx b/src/routes/_authenticated.subscribe.tsx
index 4f12197..37326f0 100644
--- a/src/routes/_authenticated.subscribe.tsx
+++ b/src/routes/_authenticated.subscribe.tsx
@@ -12,6 +12,7 @@ import { getCustomerPlanStatus } from "@/client/features/billing/plan-detection"
 import { normalizeAuthRedirect } from "@/lib/auth-redirect";
 import { useCanManageBilling } from "@/client/features/team/organizationQueries";
 import {
+  AUTUMN_CHECKOUT_SESSION_PARAMS,
   AUTUMN_MANAGED_ACCESS_FEATURE_ID,
   AUTUMN_PAID_PLAN_ID,
 } from "@/shared/billing";
@@ -200,6 +201,7 @@ function SubscribePage() {
         planId: AUTUMN_PAID_PLAN_ID,
         redirectMode: "always",
         successUrl: successUrl.toString(),
+        checkoutSessionParams: AUTUMN_CHECKOUT_SESSION_PARAMS,
       });
     } catch (err) {
       setError(
diff --git a/src/shared/billing.ts b/src/shared/billing.ts
index a539343..d1bd696 100644
--- a/src/shared/billing.ts
+++ b/src/shared/billing.ts
@@ -16,6 +16,16 @@ export const AUTUMN_SEO_DATA_CREDITS_PER_USD = 1000;
 export const SEO_DATA_COST_MARKUP = 1.28;
 export const LOW_CREDITS_THRESHOLD_USD = 0.25;
 
+// Passed through to Stripe's checkout.sessions.create so checkout collects the
+// legal business name, tax ID (EU VAT etc.), and full billing address — makes
+// invoices valid for business customers. Display only, no Stripe Tax. Stripe
+// requires customer_update.name "auto" to collect tax IDs for an existing customer.
+export const AUTUMN_CHECKOUT_SESSION_PARAMS = {
+  tax_id_collection: { enabled: true },
+  billing_address_collection: "required",
+  customer_update: { name: "auto", address: "auto" },
+} as const;
+
 export function roundUsdForBilling(value: number) {
   return Math.round(value * 100000) / 100000;
 }