Refunds are based on the token that was captured when the original payment was made. Depending on the situation, refunds may still be able to be processed normally, even if the original card used has expired or longer valid. In these cases, the funds will still be returned to the account associated with the card on file. 

Certain changes to the credit card, like a new expiration date or even card number are usually fine, provided the account is still active, and the credit will go back to the same account.  If you see a refund transaction associated to that order in ACME but the consumer does not see these funds automatically appear in their account after 10 business days, we recommend that they reach out to their bank or card issuer to inquire on the status, as it is ultimately depends on the updates that the bank makes to the account.

If the account is closed and cannot receive a credit, then you will need to issue a manual check refund to the guest and submit a data fix request for ACME to correct the order data to reflect the manual refund. 

If you are experiencing an "Invalid Account" error when attempting a refund, you will also need to request a data fix as outlined here.