Decline code

When a card payment fails, the response usually carries several codes. The issuer’s network decline code is a short code whose meaning depends on the card brand. Processors translate it into their own readable codes, such as Stripe’s insufficient_funds or expired_card. Some networks also send an advice code that says whether, and when, to try again; Mastercard calls these Merchant Advice Codes.

Codes are not always precise. Generic codes such as do_not_honor or generic_decline hide the real reason, often on purpose when the issuer suspects fraud, and the customer may need to call their bank.

For recurring billing, decline codes drive the recovery strategy: retry later for a temporary problem, ask the customer for a new card for a permanent one, and never retry codes that the network says not to retry.