MED is not a chargeback: anyone hit by an improper return gets 80 days to react

Pix's Special Return Mechanism (MED) is explained almost everywhere as "the way to get your money back." The description isn't wrong, but it's only half the picture — and the missing half is the one that creates liability.

The MED has a narrow perimeter, defined by regulation, and a counterweight: whoever is debited by it can push back. That counterweight changes on September 1, 2026.

The perimeter

The Banco Central implementation guide is explicit about what does not qualify as a MED case. These are not fraud scenarios, and therefore fall outside the mechanism:

"purchase transactions initiated by the paying user whose purchased goods were delivered late, or did not please the user, or did not exactly match expectations, or were not exactly the same model as purchased, or any other commercial dispute that cannot be characterized as seller fraud"

— MED Guide, section 4.2.3 (Cases)

Nor does it apply when the funds ended up with someone who had nothing to do with the fraud:

"transactions initiated by the paying user that resulted from some fraud, scam or crime, but whose funds were used to purchase a product or service from a third party acting in good faith"

— MED Guide, section 4.2.3 (Cases)

The document closes the distinction with a sentence that deserves a place in every primer on the subject:

"the return ordered by the payee's PSP in cases of well-founded suspicion of fraud is completely different from the chargeback that exists in payment card arrangements. Within Pix, it is not enough for the paying user to simply not recognize a purchase in order to have the funds returned."

— MED Guide, section 4.2.3 (Cases)

Commercial disputes, the rulebook says, are settled in court.

The counterweight, and what changes in September

When someone is debited by a MED they consider improper, there is a way back: contesting the return transaction.

Today that window is 30 days, counted from the return — it is set out in questions 10 and 11 of the guide's FAQ. Under version 4.4, effective September 1, it becomes 80: the same window that already applied to contesting an original transaction. What the change does, in practice, is eliminate a special case. There were two clocks; now there is one.

It's worth stating what this change is not, because the distinction got lost in the coverage. The window for a scam victim to trigger the MED is 80 days, and always was. What tripled is the window on the other side — for whoever took the debit.

The flow has three features that set it apart from an ordinary MED, all described in section 5.2 of the guide, and all three matter operationally:

It isn't automatic. Unlike a MED over an original transaction, the participant is not required to open the recovery immediately. The payee's PSP "may analyze the merits of the request and, should it find the contestation of the return warranted, proceed with opening the Funds Recovery."

The roles flip. The payee's PSP "will now act as the recovering PSP, since the return transaction being contested originated with it."

The return becomes the starting point. The system "will execute the entire flow treating the return transaction as the root transaction of the Funds Recovery." That is why its age matters — and why 30 versus 80 days changes the reach of the instrument.

Every wrong call has an owner

This is the part that rarely makes the coverage, and it's the part that determines exposure. It's all in section 5.4 of the guide, on liability.

The rulebook doesn't treat the MED as a process in which money either comes back or doesn't. It names, step by step, who bears responsibility when the call is wrong:

Improperly rejecting the infraction notification. If the payer's PSP rejects the notification generated by a contestation of a return, "it becomes liable for returning funds in cases that are, in fact, an improper return."

Failing to open the recovery when it was warranted. If the payee's PSP does not open the recovery and the return stemmed from fraud by the paying user, "liability for any improper returns lies solely and exclusively with the payee's PSP" — and its own customer may open a dispute against it.

Cancelling midway. If the notification was accepted and the payee's PSP cancels the recovery, liability for an improper return reverts to it.

In every scenario, the losing party in a dispute between participants may go to court. What the rulebook organizes is where the bill lands first.

Note what is absent from that list: under no circumstance is a PSP required to make the return out of its own funds when the destination account has no balance or has been closed. Liability arises from the decision, not from the outcome.

Why this matters now

For anyone receiving payments via Pix — merchants, service providers, platforms — the MED is an operational risk that looks nothing like card risk. There is no commercial contestation period, there is no "I don't recognize this purchase," and the defense is not automatic: it depends on the PSP reviewing the merits and acting within the window.

That window goes to 80 days on September 1. More time to react, and also more time during which a return already received can be challenged.

For those running the MED on the institution side, the reading is different. A longer window increases the volume of possible contestations and keeps cases open for longer — with liability, at each step, expressly assigned.

The MED was designed narrow. Treating it as a chargeback doesn't broaden the instrument; it just moves the liability.

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Sources

Guia de implementação dos procedimentos de devolução no Pix, com ênfase no Mecanismo Especial de Devolução — Banco Central do Brasil. Version 4.3, currently in force and version 4.4, effective September 1, 2026. The passages quoted are identical in both versions.