diff --git a/app/billing/routes.py b/app/billing/routes.py
index 75d10ec..d4f7a2d 100644
--- a/app/billing/routes.py
+++ b/app/billing/routes.py
@@ -105,7 +105,8 @@ def subscribe():
         price_id           = plan.stripe_price_id
 
     # Create Checkout Session AFTER the control_session commits customer_id.
-    base_url = (current_app.config.get('APP_BASE_URL') or request.host_url).rstrip('/')
+    # Use request.host_url so success/cancel redirect back to the tenant's domain.
+    base_url = request.host_url.rstrip('/')
     try:
         session = create_checkout_session(
             customer_id=stripe_customer_id,
@@ -147,7 +148,9 @@ def portal():
             return redirect(url_for('tenant_settings.plan'))
         stripe_customer_id = t.stripe_customer_id
 
-    base_url   = (current_app.config.get('APP_BASE_URL') or request.host_url).rstrip('/')
+    # Use the actual request host so the return URL matches the tenant's domain,
+    # not the global APP_BASE_URL which points to the primary domain.
+    base_url   = request.host_url.rstrip('/')
     return_url = f'{base_url}/settings/plan'
 
     try: