Stand-in processing is the card network answering authorization requests on an issuer's behalf when the issuer's own systems do not respond. Scheme documentation writes it as STIP, stand-in processing or stand in processing, all the same thing: the network applies parameters the bank filed in advance and returns an approval or a decline in the bank's name, so an outage does not become a wall of failed payments.
The parameters a bank files in advance
An issuer decides beforehand what the card network may approve for it: a ceiling per transaction, how many consecutive stand-in approvals a single card may collect, which merchant categories are in or out, and what to do with cards already flagged lost, stolen or expired. Inside those limits the scheme approves; outside them it declines.
The network cannot see the account balance, so none of this is a funds check. It is a status check plus a pre-agreed risk appetite, which is why the ceilings are usually modest.
What happens when the bank comes back
Payments approved during the outage are delivered to the issuer once it is reachable, and the account is debited then. If the money was not there, the issuer finds out after the fact. Cardholders notice nothing at the time: a payment at 3am during a maintenance window comes back in the usual second or two.
The issuer wrote the rules, so the issuer keeps the loss
Liability follows authorship. The bank set the parameters, the scheme applied them faithfully, and the merchant is paid as if the issuer had answered directly. That is the opposite allocation to offline authorization, where the terminal decides and the merchant absorbs the failures — same symptom at the till, different actor, different party out of pocket.
Spotting it in a decline report
Merchants cannot request STIP or configure it, so the useful skill is recognizing its edges. A cluster of declines concentrated on one BIN range, inside a narrow time window, on cards that worked yesterday, is an availability problem: either the issuer is unreachable and the payment fell outside its stand-in limits, or a card has exhausted its consecutive stand-in count. Those orders belong in a decline recovery queue on a delayed retry, not in the write-off pile with genuine insufficient-funds results.
The contribution nobody credits
Because it works, stand-in processing is invisible. Every maintenance window it covers is volume that would otherwise land on the merchant as a decline on a perfectly good card. That is worth remembering when comparing authorization rates across months: a period containing a large issuer outage can move the number without anything changing on the merchant's side.