Merchant Advice Code

What is a merchant advice code?

Merchant advice code (MAC) is a two-digit code Mastercard returns in the

response to tell the merchant why a payment was declined and what to do next. It sits alongside the

: the decline code names the reason, the MAC names the recommended action.

A MAC gives the merchant a read on the

account status without exposing account detail. Depending on the reason, the same transaction can be resubmitted later. A card limit that's been exceeded often clears within days, so the issuer returns a retry interval rather than a flat refusal. Other values say the opposite: the credential is dead and no resubmission will be approved. The code reaches the merchant through the

payment processor

as a separate field in the authorization response payload.

Key facts

Also known as: MAC
Set by: the
issuer
, passed through the Mastercard network to the acquirer and the merchant
Format: two-digit numeric value returned in the authorization response
Scope: Mastercard transactions. Other card networks signal retry guidance through their own response-code sets.
Most used in:
recurring payments
and
dunning
, where the retry decision is automated rather than manual

Types of merchant advice codes

MAC values fall into four groups: refresh the stored credential, stop retrying, retry after a set interval, and advisory notes about the card product.

Code	What it means	Retry guidance
01	New account information available	Only after updating the stored credential
02	Cannot approve at this time, try again later	Yes, no interval specified
03	Do not try again	No
04	Token requirements not fulfilled for this token type	No, resolve the token setup first
21	Payment cancellation	No, stop the recurring charge
24	Retry after 1 hour	After 1 hour
25	Retry after 24 hours	After 24 hours
26	Retry after 2 days	After 2 days
27	Retry after 4 days	After 4 days
28	Retry after 6 days	After 6 days
29	Retry after 8 days	After 8 days
30	Retry after 10 days	After 10 days
40	Consumer non-reloadable prepaid card	Advisory, not a decline instruction
41	Consumer single-use virtual card number	Advisory, not a decline instruction

Codes 40 and 41 aren't retry instructions. They describe the card product, which changes what a subscription business can do next: a single-use virtual card number can't be charged again, so the stored credential needs replacing before the next billing cycle.

Why it matters

It separates recoverable declines from dead ones. MAC 03 means the issuer will decline every resubmission of that transaction, so further attempts spend processing fees without recovering the payment.
It sets the retry clock. Codes 24 to 30 name the interval after which the issuer will reconsider the charge. A retry sent before that interval hits the same decline.
It flags stale credentials. MAC 01 means the issuer holds updated card details for the account, so the fix is refreshing the stored credential rather than resubmitting the old one.
It keeps retry volume inside network rules. Mastercard limits how often a declined authorization can be resubmitted, and merchants past those limits face additional fees. The thresholds sit in Mastercard's scheme rules and vary by region – the applicable version is in the acquirer agreement.