We would like to explain that the option of coupon i.e. available under the subscription upgrade/downgrade section will be applicable to the new assigned subscription only. In simple words, if the subscription is switched then while selecting the plan if a merchant applies the coupon code from their end then the instant discount will be applied to the newly assigned plan so that the total will be generated at a discounted price.
Further, by clicking on save, a pop-up window will be displayed stating all the info including the duration of the old subscription used & based on that a credit will be managed in automation mode that will instantly calculate the amount & will display the final total adjusted i.e. based on credits it'll show whether how much amount will be paid or refunded accordingly. Therefore, in the case of refund, it'll simply set that amount as credits for the customer's subscription that will be used automatically in the next billing. So basically, the refund is being adjusted in the form of credits automatically through the software.
Hence, in this way, the coupons & credits are managed separately while switching the subscription for a customer in Pabbly Subscription Billing.
For more info, please follow this doc -
https://www.pabbly.com/subscriptions/docs/features/#section5
