Discounts are a great way to increase signups, conversion and retention. The easiest way to handle promotions and discounts is to send out coupon codes. Coupon codes can be created from the Stripe dashboard, then customers can enter them from checkout or add them to existing subscriptions on the customer portal.
Below are the steps to enable this feature.
Create a new coupon in Stripe. Note that the Coupon ID is what customers need to enter to redeem the coupon, not name. Stripe 'customer-facing' coupon codes or Promo Codes can also be used to redeem a coupon.
Go to your billing page and enable the option for coupons.