Enable Stripe Tax and apply automatic tax calculation to payment intents and subscriptions

Verified steps

1. Enable Stripe Tax in the Stripe Dashboard under Settings > Tax; complete the registration wizard by adding your business address and at least one tax registration for the jurisdictions where you have nexus.
2. For one-time payments, include 'automatic_tax[enabled]=true' in your PaymentIntent creation request; this requires the PaymentIntent to have a 'customer' with a valid billing address — Stripe uses the customer address to determine tax jurisdiction.
3. For subscriptions, set 'automatic_tax[enabled]=true' on the Subscription object at creation; Stripe will automatically apply the correct tax rate on each invoice based on the customer's address at the time of billing.
4. Ensure your Products and Prices have 'tax_code' set appropriately — Stripe Tax uses tax codes (e.g., 'txcd_10000000' for general physical goods, 'txcd_99999999' for non-taxable) to determine product taxability; missing tax codes default to Stripe's standard classification.
5. Retrieve tax breakdown from a created Invoice or PaymentIntent by expanding the 'automatic_tax' field; each tax amount entry includes 'jurisdiction', 'tax_type', and 'inclusive' boolean.
6. For Checkout Sessions, set 'automatic_tax[enabled]=true' in the session creation parameters; Stripe handles address collection and tax display automatically in the hosted checkout UI.