Does Cat S show on the V5C?

No — a vehicle's write-off category (Cat S, Cat N, or older classifications like Cat C/D) is not shown on the V5C logbook. The V5C covers registration and keeper details, not insurance or write-off history, so a car can have a Cat S history while its logbook looks completely standard.

Where write-off status is actually recorded:

Write-off category is held by the insurance industry's shared database, which insurers use to record vehicles they've declared a write-off. This isn't something the DVLA collects or displays as part of the V5C or standard registration record — it's a separate system entirely, similar to how outstanding finance and stolen reports also sit outside DVLA's own records (see what is the difference between Category N and Category S for what these categories actually mean).

How to actually check:

The only reliable way to find out whether a vehicle has a write-off history is through a check that specifically queries this insurance industry data, typically bundled into a full vehicle history check alongside things like outstanding finance and mileage records.

Why this catches buyers out:

Because the V5C looks identical whether a car has a clean history or a Cat S repair in its past, relying on the logbook alone gives a false sense of confidence — it's simply not the document that would show this information, even for a car with a well-documented and properly repaired structural history.