How does a merchant advice code work?
The issuer’s response carries a response code, such as 05 or 51, and Mastercard adds a merchant advice code that turns it into an instruction. PayPal’s and Primer’s documentation list the main values: 01 updated information needed, 02 cannot be approved now, try again later, 03 do not try again, 04 token requirements not fulfilled for this token type, 21 payment cancellation or stop recurring payments, and 24 to 30 for insufficient funds with a suggested retry after 1 hour, 24 hours, or 2, 4, 6, 8 or 10 days.
Why does the merchant advice code matter?
It can change the meaning of the same response code. Stripe’s list of Mastercard codes shows 05 do not honor arriving with MAC 01, 03 or 21, each needing a different action. It also prevents waste: Mastercard’s soft-decline rules charge after 10 retries in 24 hours or 35 in 30 days. As an illustrative example: a subscription merchant receives 1,000 insufficient funds declines with MAC 25 to 27. Retrying all of them the next morning ignores the advice and uses up attempts; retrying each on the day the code suggests uses one attempt per payment and arrives when the account is more likely to be funded.
What are the risks of ignoring it?
Fees, and a pattern issuers read as poor practice. Retrying after MAC 03 or 21 is charged even when the retry goes through a different acquirer, because the network sees the card, not the route. The safest policy maps each MAC to an action once and applies it to every provider.
Where does Omno use it?
Omno moves a payment to the next provider in the merchant’s routing rule when a provider rejects it, and the routing-decision log keeps the decline details and advice code for each attempt.