Car Write-Off Categories Explained: Cat A, B, S and N
When an insurer writes a car off, it assigns one of four categories — A, B, S or N — and that single letter decides what can legally happen to the car next: whether it must be crushed, whether you can buy it back, and how much it's worth for the rest of its life. Since October 2017 these four have been the UK system; the old Cat C and Cat D markers still appear on older cars and have their own guide.
Free to check, no obligation — and you can challenge your insurer yourself for free, with the Financial Ombudsman free after that. This takes you to Allegiant Finance Services, our car write-off partner — Claims Bible is paid for accepted introductions.
The four categories at a glance
| Category | Can it be repaired? | What happens to the car |
|---|---|---|
| Cat A | No | The entire vehicle must be crushed — nothing can be salvaged |
| Cat B | No | The body shell must be crushed, but parts can be salvaged and sold |
| Cat S | Yes — structural damage | Can return to the road once repaired to a roadworthy condition, marked Cat S for life |
| Cat N | Yes — non-structural damage | Can return to the road once repaired to a roadworthy condition, marked Cat N for life |
The split that matters: A and B are about safety — the car (or its shell) is beyond saving. S and N are usually about money — the car could be repaired, but the insurer has decided the repair bill is too high relative to the car's value. That's why a perfectly repairable car can still be "written off": it's an economic decision, not a mechanical verdict.
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Cat S: structural damage
Cat S means the damage reached the car's structure — the chassis or the parts of the body that do the structural work. It can be repaired and driven again, but the repair needs to be done properly, and the marker stays with the car forever. Full detail, including the buy-back paperwork that's unique to Cat S: what is a Cat S car?
Cat N: non-structural damage
Cat N covers everything else — bodywork, electrics, interior, and importantly also brakes, steering and suspension, which are classed as non-structural despite being safety-critical. Full detail: what is a Cat N car?
Who decides the category — and can it be wrong?
The insurer's engineer assigns the category when the claim is assessed. It's a judgement, and it can be challenged. The category is worth arguing about because it isn't cosmetic: a harsher category than the damage justifies means a lower salvage value, weaker buy-back terms and a bigger permanent dent in the car's worth. If the category looks wrong, the same complaint route as a low valuation applies — the insurer's complaints process first, then the Financial Ombudsman Service, free, whose decisions bind the insurer.
The category affects your payout too
Whatever the category, the settlement itself should be the pre-accident market value of your exact car — what replacing it would actually cost, not a trade price. The category interacts with that number mainly through salvage: keep a Cat S or N car and the salvage value is deducted from your payout. Our guide to how much you'll get works through the sums, and its settlement gap checker tests the insurer's offer against your own replacement-cost research.
The DVLA side, briefly
Whichever category applies, the insurer usually handles the scrapping or salvage, but the legal duty to tell DVLA the car has been written off sits with you — and not telling them can mean a £1,000 fine. Keep the yellow "sell to the motor trade" section of the V5C when the log book goes to the insurer. The steps differ slightly if you keep the car — the Cat S and Cat N guides cover their own paperwork — and gov.uk carries the official process.
Frequently asked questions
Can a category be removed from a car?
No. Once applied, the marker stays on the vehicle's record for life — repairing the car to a high standard doesn't remove it, which is exactly why the marker exists for future buyers.
Is a Cat S car worse than a Cat N?
Generally, yes, in value terms — structural damage carries more stigma and more repair risk than non-structural. But a badly repaired Cat N can be a worse car than a properly repaired Cat S; the marker tells you what was damaged, not how well it was fixed.
What were Cat C and Cat D?
The pre-2017 equivalents, based on repair cost rather than damage type. Cars written off before October 2017 still carry them — our Cat C and Cat D guide explains how they map to today's system.
My car was given a category I don't agree with. What can I do?
Ask the insurer to explain the categorisation, put your disagreement in writing as a complaint if the explanation doesn't hold up, and escalate to the Financial Ombudsman if their final response doesn't resolve it. The category and the valuation can be challenged together.
