With the Refunds API you can return collected funds back to your customer. The refunded amount will be deducted from your Mollie account balance.
If your Mollie account does not have sufficient balance to perform the refund, the refund will be put on hold temporarily. We will automatically attempt to process the refund again as soon as your balance sufficiently increases.
Refunds for payment-based and order-based integrations are slightly different. Each have their own endpoints accordingly.
Please refer to the Refunds guide for more details about processing refunds.