Promotions and tax
Let Stripe own promotion codes and tax, while each order keeps its own evidence.
Stripe decides promotion eligibility and calculates tax. Next License records what was allowed and what Stripe charged, and checks the arithmetic before issuing a license.
Promotion codes
Set Stripe__AllowPromotionCodes=true to show a promotion-code field in Stripe Checkout. Create coupons, codes, restrictions and expiry dates in the Stripe Dashboard. Next License keeps no copy of your promotions and no redemption counter; there are no referral payouts or discount-stacking rules.
Automatic tax
Set Stripe__AutomaticTax=true to enable Stripe Tax for new Checkout sessions. Configure your tax registrations and product tax codes in Stripe. Prices must be tax-exclusive.
How orders are checked
Before redirecting, each order records whether promotion codes and automatic tax were allowed. Changing these settings later doesn't affect orders already started.
Fulfillment then checks the original subtotal, quantity, currency and Stripe price, and confirms that any discount was allowed, that total = subtotal − discount + tax, and that payment succeeded. The resulting settlement, including the promotion code used, is immutable.
A fully discounted order requires a completed no_payment_required session with a zero total, and is only accepted when promotion codes were allowed. No payment is simulated locally. Its update term begins when completion is first observed.
Test first
In your Stripe test environment, try eligible and ineligible codes, expired codes, currency restrictions, a 100% discount and tax before enabling these settings for live sales.