Reason code · American Express
Amex M01: chargeback authorization
M01 means you agreed to it. Your reply to an Amex inquiry authorized Amex to charge back the disputed amount. There’s nothing to fight, but there is something to check: that you didn’t also refund the customer directly.
What M01 means
M01 is the one Amex code you sign off on yourself. Amex’s guide says it means Amex received your authorization to process a chargeback: your reply to an inquiry told Amex to go ahead and take back the disputed amount.
An inquiry is Amex asking for your side before money moves. One of your options is to agree that the customer should get their money back. M01 is that agreement turned into a chargeback.
A label you may see instead
Labels don’t always match. Chase’s processor guide shows M01 as “Chargeback Authorization” in its code list but “Local Regulatory/Legal Disputes” in its time-frame table. Amex’s own guide, Checkout.com and Stripe all call M01 Chargeback Authorization, and Amex treats local regulatory and legal disputes as a separate reason. Go by the description on your notice.
Time limit
Processor guides list this code at 120 days from the transaction date, the same as most Amex codes. Checkout.com marks it as one that requires an inquiry first, so it follows an earlier request from Amex.
Your side of the clock is short. Amex’s own guide tells merchants to respond within 20 days. If you accept Amex through a processor such as Stripe or Square, the processor sets its own date, often a shorter one. The due date on your notice is the one that counts.
What proof matters
Amex’s guide lists one response: proof that a refund directly offsetting the disputed charge has already been processed. Amex’s prevention advice is simply “not applicable,” since you asked for this.
Watch for the double refund
The real risk on M01 isn’t losing. It’s paying twice. A customer complains, someone at your business refunds them, and someone else replies to Amex’s inquiry agreeing to the chargeback. Now the money has gone back twice. If a refund already went out, M01 is the moment to prove it.
Amex’s guide is clear on the right way to concede: if you agree credit is due, respond by the reply due date with your authorization for a chargeback. Pick one route for the money, not both.
The common mistake
Treating M01 as “nothing to do.” Check your refund records against every M01 before you close it out.
Dispute Daddy builds this for you
Upload the notice and your records. Dispute Daddy builds a response around the reason Amex actually gave, and you approve it before you submit. See how the method works.
