A declined debit transaction isn't always successful fraud prevention.
Sometimes it's a good customer standing at a checkout counter.
One finding in the 2026 Issuer Risk Playbook caught my attention. The share of card issuers citing insufficient fraud systems and high false declines as a pain point with their processor rose from 14% to 21% in a single year.
For a debit issuer, a legitimate transaction that gets declined is interchange that never gets earned. That part is easy to see.
What's harder to see is what happens to that card afterward.
Most banks can tell you their fraud loss. Far fewer can tell you what a declined cardholder's transaction volume looked like sixty days later, measured against a cardholder who wasn't declined.
That second number is sitting in data the bank already has. It just isn't a report anybody runs.
So there are two questions, and they aren't the same measurement:
How much fraud are we stopping?
And how many good transactions are we stopping with it?
A bank that can answer the first but not the second has a blind spot, and no way to size it.
How you'd run it: transaction counts per card, 90 days before a decline versus 30/60/90 after — the same card against its own history. Then run that identical before/after on cards with similar prior activity that weren't declined, and subtract. That second step is what keeps you from crediting the decline for a drop that was coming anyway. One caution — strip out insufficient-funds declines first, or none of it means anything.
Source: PYMNTS Intelligence / Visa DPS, The Issuer Risk Playbook, 2026. Survey of 500 executives in head-of-payments roles at U.S. bank and non-bank card issuers, fielded Dec. 16, 2025 – Jan. 14, 2026.