Car Write-Off Categories Explained: Cat A, B, S and N

Write-off categories tell you how badly a car was damaged when an insurer decided not to repair it. Since October 2017 there have been four: Cat A and Cat B cars can never return to the road, while Cat S (structural damage) and Cat N (non-structural damage) cars can be repaired and driven again. A repaired Cat S or Cat N car can be a sensible buy at the right price, as long as you know its history and the repairs were done properly.

The write-off categories at a glance

The core definitions come from GOV.UK's guide to insurance write-offs. Insurers record write-offs on the Motor Insurance Anti-Fraud and Theft Register (MIAFTR), which is how a history check finds them.

What were Cat C and Cat D?

Before October 2017, insurers used Cat A, B, C and D. Cat C and Cat D were both repairable, and the split depended on cost: a Cat C car's repair costs exceeded its value, while a Cat D car's repair costs were lower than its value but the insurer chose not to repair it.

The newer system looks at the type of damage instead of the bill, so Cat D isn't simply the old name for Cat N. You'll still see Cat C and Cat D on the histories of older cars, and the same buying advice applies.

Why do insurers write off repairable cars?

An insurer writes a car off when repairing it doesn't make financial sense, typically because the repair bill would exceed the car's value. GOV.UK calls this a constructive loss.

That's why the age and value of the car matter so much. Damage that a newer car would be repaired for can write off an older, cheaper one. A write-off tells you the repair was big relative to the car's value at the time, not necessarily that the car was wrecked.

Cat S vs Cat N: what's the difference?

Cat S cars have structural damage. That can include the chassis, the structural frame or the parts designed to absorb a crash. Repairs need the right equipment and skills, and a poor structural repair can affect how the car protects you in another accident.

Cat N cars have non-structural damage, which can range from body panels and lights to electrical components. The label tells you the structure wasn't damaged, not that the damage was trivial: the repair bill was still big enough for the insurer to write the car off.

There's a paperwork difference too. When a keeper keeps a Cat S car, GOV.UK says they must send the logbook to the insurer and apply for a free duplicate V5C, and DVLA records the category in the logbook. A Cat N car's keeper can keep the existing logbook.

Should I buy a Cat N or Cat S car?

It depends on the price, the repair and your plans. Here's the balance:

A repaired write-off makes most sense if you're paying cash, plan to keep the car for years and can verify the repairs. It makes least sense if you need finance, expect to sell soon, or can't find out who repaired it and how.

Between the two, a Cat N car is usually the easier decision, because its structure wasn't damaged. A Cat S car isn't automatically a bad buy, but the repair evidence matters even more.

Insurance and finance: what changes after a write-off

Speak to your insurer before you buy, not after. GOV.UK's guide to buying repaired written-off vehicles warns that not all insurers will automatically cover a previously written-off car, so get a quote with the category declared.

Once you've bought it, tell your insurer about the write-off. If you don't, the insurer can reject a claim for non-disclosure. And if the car is written off again, any payout is based on its market value, which is typically lower than for a similar car without a write-off.

Finance can be harder too. Some lenders won't finance a Cat S or Cat N car, so check with your lender before you commit if you're not paying cash.

If your own car is written off and you keep it, you must tell DVLA. GOV.UK warns you can be fined £1,000 if you don't.

How much less is a written-off car worth?

There's no fixed figure. Cat S and Cat N cars are typically sold at a discount, and the gap depends on the category, the extent of the damage, the quality of the repair, the model and how many buyers want one.

The fairest way to judge a price is to compare it with similar cars of the same age and mileage that haven't been written off, then knock off what you'll lose: higher insurance, possibly costlier finance and a lower price when you sell. Our guide to how much your car is worth explains what else affects values.

How to find out if a car has been written off

1. Ask the seller directly, and get the answer in writing: "Has this car ever been recorded as an insurance write-off?"
2. Look at the V5C. For a Cat S car kept after the write-off, DVLA records the category in the logbook. Don't rely on the logbook alone, though.
3. Run a full history check. The full car history check in our app shows insurance write-off records from MIAFTR, including the category and date of loss, plus salvage auction records, which can include photos of the damage, a damage description and the mileage at auction.
4. Read the MOT history for clues. A long gap followed by a fresh MOT can mark the time the car was off the road being repaired. Run a free MOT history check and see our guide to checking MOT history for what else to look for.

What sellers must tell you about a write-off

Dealers mustn't mislead you, either by what they say or by what they leave out. Consumer protection law, now in the Digital Markets, Competition and Consumers Act 2024 after replacing the 2008 regulations in April 2025, treats leaving out information you need to make an informed decision as a misleading omission, and a known write-off history is the kind of information that's likely to count. The Consumer Rights Act 2015 also requires a dealer's car to be as described and of satisfactory quality.

Private sellers aren't bound by the same trader rules, but the car must match their description. If you ask whether it's been written off and they say no when it has, you may have grounds for a claim. That's why it's worth asking in writing.

Either way, don't rely on the seller's word alone. A history check shows you the record for yourself.

How to check the quality of repairs

There's no official inspection of the repairs before a Cat S or Cat N car returns to the road; the old Vehicle Identity Check scheme ended in 2015. An MOT checks roadworthiness on the day, not the standard of the repair. So the checking is down to you:

• Ask for the repair history: invoices, photos of the damage and who did the work. GOV.UK suggests asking who handled the car between the write-off and its return to the road.
• Compare with salvage auction photos, if a history check has them, to see what the damage looked like before repair.
• Look closely: uneven panel gaps, mismatched paint, overspray on seals, rippled filler, and fresh welds or sealant underneath.
• Check the tyres and steering: uneven tyre wear or a car that pulls to one side can point to alignment problems after a structural repair.
• Watch the warning lights: an airbag light that stays on is a serious concern.
• Get an independent inspection. GOV.UK suggests an independent report or an engineer's check for structural damage, and Citizens Advice puts inspections at around £120 to £250.

Next steps: check the record before you commit

If you're looking at a car with a write-off history, or one that seems cheap for no obvious reason, check it before you travel: a free car check for the MOT history and mileage, and a full history check for the write-off record. Then get an insurance quote with the category declared, ask for the repair evidence and arrange an inspection.

Use our used car buying checklist at the viewing, and walk away if the seller won't let the car be inspected. A well-repaired Cat N or Cat S car at the right price can be good value; an unknown repair at a near-normal price rarely is.