What the acquirer asks, and why.

Fictional scenarios and synthetic data. Reviewed 6 November 2026.

An e-mail from Stilling Bank arrives at Northbank Pay on the third working day of the month. The subject line is a merchant ID. The body asks for Brightwater Tickets' fraud and dispute figures for the previous month, the controls in place, and a plan. Ines forwards it to the reader with one line: "They are asking because they have to. Let us answer as if we had been expecting it."

What is actually being decided.

The acquirer is deciding whether the PSP's portfolio is a risk it can carry. Scheme monitoring programmes measure the acquirer as well as the merchant, and an acquirer whose own ratio drifts above a programme threshold is answerable to the scheme. So when Stilling Bank asks about one merchant, it is asking two questions at once: is this merchant going to cost us, and does this PSP know what it is doing?

The merchant carries fees and, at the far end, the loss of card acceptance. The PSP carries its standing with the acquirer, which is the asset that lets it onboard the next merchant. The acquirer carries the scheme. Each party is downstream of the other's numbers, which is why the conversation goes better when everyone has the same ones.

Question one: what is the ratio, and what is in it.

Programme classification depends on the network, region, reporting period, applicable entity and the current rules. Reconcile the acquirer’s event counts and exclusions before comparing a calculated rate with a confirmed threshold. Do not treat a generic floor, ratio or fee quoted in a summary as a universal programme decision.

In this synthetic illustration, Brightwater has 120,000 eligible settled transactions, 1,100 fraud events and 700 disputes before adjustments. The raw ratio is 1,800 / 120,000 = 1.50%. If the acquirer confirms that 150 dispute events are excluded in this extract, the adjusted numerator is 1,650 and the ratio is 1.375%. Keep both calculations, the recognised adjustment and the extract date. Neither number alone determines programme entry.

The answer to question one is therefore not "1.5 per cent" and not "1.375 per cent". It is both numbers, with the components and the month, and a sentence explaining the difference. An acquirer that sees you know the difference asks fewer follow-up questions.

The alternative we keep alive: our reading of how the components are counted comes from acquirer summaries, and Stilling Bank's own calculation is the one that counts. Ask them to confirm which figure they hold, and confirm the rest with your acquirer and counsel.

Question two: why does the acquirer care if the merchant is in scope.

Programme classification depends on the network, region, reporting period, applicable entity and the current rules. Reconcile the acquirer’s event counts and exclusions before comparing a calculated rate with a confirmed threshold. Do not treat a generic floor, ratio or fee quoted in a summary as a universal programme decision.

Question three: what controls are in place.

"We have a sophisticated risk engine" is not an answer. The answer is a list of rule sentences, each with its purpose, budget and owner, as set out in A rule is a claim, and a sample of case notes in the form from Write the note for the person who reopens it. An acquirer, like an auditor, needs to be able to read a control without your tools and see that it existed on the date in question. a one-page table (rule, purpose, live since, owner, last reviewed) does more for the relationship than any description of the technology behind it.

If link analysis contributed to an action, the acquirer will want the path, not the picture: which accounts, linked by which attribute, with what base rate. A shared attribute is a lead is written to that standard for that reason.

Question four: what is the plan.

A remediation plan is scoped actions with owners, dates and a target the acquirer can measure next month. In this illustration, Northbank's plan for Brightwater has three lines. First, enrol the merchant in pre-dispute alerts for its two largest issuers by dispute volume, owner Tomas, live by the 15th; expected effect, a reduction in the dispute component, not the fraud component. Second, lower the fulfilment threshold for a held-for-review decision on on-sale days, owner the reader, live by the 10th, review on the 30th; the cost matrix in The threshold is a price is attached. Third, a weekly ratio report to Stilling Bank for three months, owner Ines. The target is the ratio below 1.2 per cent on the acquirer's own calculation within two reporting months.

Confirm any applicable assessment, grace period and exit conditions directly with the acquirer. Record the rule version and affected reporting month rather than deriving a bill from a generic per-event figure.

Question five: what have you not told us.

The question the acquirer does not write down. Visa’s dispute-resolution guidance describes a lifecycle in which a dispute reaches the merchant weeks after the transaction, with a window for evidence and a decision after that. The acquirer therefore sees an incident in its numbers one to three months after the PSP saw it in its traffic. A PSP that reports an overnight burst at Pondside Gifts on the morning after, with the note from The first fifteen minutes attached, is telling the acquirer something it would otherwise learn from a ratio in February. that single habit changes the tone of every later conversation.

A failure mode to watch.

The PSP answers the e-mail with the number the acquirer already has, an adjective ("robust"), and a promise. No components, no controls in a readable form, no dated plan. The acquirer's next e-mail is longer, copied higher, and arrives with a deadline. The relationship moves from a monthly conversation between risk teams to a quarterly one between executives, and the merchant, who was never told any of this, finds out when acceptance is withdrawn.

A way to work it.

1. For every merchant above half the summarised merchant threshold, compute the ratio monthly on the first working day, with components, before the acquirer can ask.
2. Keep the one-page controls table current: rule, purpose, live since, owner, last reviewed. It is the answer to question three.
3. Keep a merchant file with the acquirer-notification threshold agreed in Reading a merchant before the first transaction, and the on-call actions allowed.
4. When a ratio moves, write the plan in three lines with owners and dates before writing to the acquirer.
5. Report incidents on the day after, not in the month after.
6. Once a quarter, ask Stilling Bank for the ratio as they calculate it, and reconcile it with yours. Differences are findings.

Take it to the desk.

If Stilling Bank asked us tomorrow for one merchant's ratio, its two components and our plan, how many hours would it take us to answer, and why not minutes?

Try it: A merchant's ratio is heading toward the excessive threshold Look up: VAMP ratio · RDR · dispute

The Volume 01 note Disputes and time explains the lag that makes question five matter, and the lesson Measuring errors is where the numerator's two parts first appear. The Volume 02 case vamp-portfolio-call is this e-mail with a decision at the end.

Edited 6 November 2026. Primary references are listed above; fictional scenarios are not claims about Antifrog customers or operating experience.

Fictional learning material. Any numerical examples are synthetic. Use only authorised, appropriately minimised records for workplace exercises; do not upload customer information to this learning site.