Car write off check: what Cat S and Cat N mean, and how to check the register

Start free: decode the number plate or VIN to confirm the car matches its advert and view MOT and tax status. The actual write-off marker and category live in the industry write-off register, which the free government tools don’t expose — run an HPI-style check (£9.99–£19.99) for it. Automano gives you the free decode, explains the categories, and a £5.90 report covering the official record (DVLA, MOT history, recalls).

Both are current insurance write-off categories. Cat S (structural) means the car suffered structural damage — to the chassis or a load-bearing part — that was repaired; it can be legal to drive but should be professionally inspected and is worth notably less. Cat N (non-structural) means the damage was cosmetic, electrical or mechanical, not to the core structure, and is often the more acceptable of the two if repaired properly. A Cat S check and a Cat N check are really the same lookup of the write-off register — the register lookup that tells you which category applies comes from an HPI-style check.

It can be, at the right price and with the right checks. A repairable write-off (Cat S or Cat N) is legal to sell and drive once repaired, but the write-off marker stays on its history forever and depresses its value — so you should pay less. The key is repair quality: always have a repaired Cat S or Cat N car inspected by an independent mechanic, and factor the category into your offer. A car write off check tells you the category so you can make that call before you commit.

Cat A and Cat B are salvage-only: a Cat A car must be crushed entirely and a Cat B car’s body shell crushed (though some parts may be reused) — neither should ever be sold for road use, so if one is advertised as a runner, walk away. Cat C and Cat D are the older (pre-2017) versions of today’s Cat S and Cat N and still appear on cars written off before the system changed. The register lookup that reveals the category comes from an HPI-style check.

You can do the free groundwork — decode the VIN and number plate and view MOT and tax status — but the write-off marker and its category sit in the industry write-off register, which the free DVLA and MOT tools don’t include. For the marker itself, run an HPI-style check (£9.99–£19.99). Be wary of sites charging a premium for what is really just a free DVLA lookup with no write-off data — and of anyone claiming the write-off register is free.

A free VIN decode confirms the car matches its advert and shows MOT/tax status, but it cannot see the write-off register. That register is private industry data licensed by HPI-style providers, and it is what tells you the category (Cat S, Cat N or historic). Automano gives you the free decode, explains the categories, and a £5.90 official-record report; the write-off register check is the paid extra you run on the final car.

Automano does not license the write-off register, so the write-off marker and category are not in the £5.90 report — for them you run an HPI-style check. Automano also does not include a £30,000-style data-accuracy guarantee or damage photos. It covers the official record: DVLA data, full MOT history, mileage checks and recall cross-checks. And no lookup tells you the quality of a repair — for that you need an in-person inspection.