Authorization

The formal authorization definition is narrow: will this bank stand behind this amount, on this card, right now. The issuer checks that the card is live and not reported lost, that funds or credit cover the amount, and that the purchase fits the account's pattern, then scores fraud risk from merchant category, geography, device signals and velocity. In the EEA and the UK it also checks whether strong customer authentication was performed, or whether a valid SCA exemption was claimed.

The everyday authorization meaning — "the payment went through" — is looser than the technical one. Collecting the approved amount is a separate instruction and belongs to capture. What the issuer gives here is a promise, not a payment.

Approvals come back as a code and a reference the merchant must store. Declines come back with a reason, and the practical split is between soft declines — insufficient funds, issuer unavailable, temporary risk block — which can be retried on a sensible schedule, and hard declines such as stolen card or account closed, which must never be retried. Scheme rules penalize merchants that hammer hard declines, and processors bill for every attempt.

"Do not honor" is the frustrating middle case: the issuer refuses without explaining, usually on a risk score. It is the largest single decline reason at most merchants and the one that responds to better data rather than to more retries.

An approval sits on the cardholder's available balance until it is collected or expires. Expiry windows are set by scheme and merchant category — days for ordinary card-not-present sales, longer for travel and rentals. A merchant that abandons a sale should send an authorization reversal rather than wait out the clock. That releases the customer's money immediately and prevents the "you charged me twice" complaint that follows a stale hold sitting next to a later charge.

The same traffic sent through two acquirers will not approve at the same rate. Local acquiring, issuer relationships, network tokens, complete address and cardholder data, and a correctly coded merchant category all move the number, as does stand-in processing covering issuer outages that would otherwise surface as declines. At meaningful volume, two points of approval rate is worth more than most pricing negotiations.