Written-Off Cars: Categories Explained (Cat A, B, S, N)
When a car is badly damaged — usually in an accident — an insurance company may declare it a total loss and write it off. But not all written-off cars are the same. The category assigned to a written-off vehicle tells you a great deal about its condition, its legal status, and whether it can safely return to the road.
This guide explains the four write-off categories used in the UK, what each one means, and what to look for if you are considering buying a car with a write-off history.
What Does Written Off Mean?
When an insurer writes off a vehicle, it means the cost of repairing it is judged to be uneconomical relative to the car's pre-accident value — or that the damage makes the vehicle unsafe to repair. The insurer pays out a settlement to the policyholder and takes ownership of the vehicle.
The vehicle is then assigned a write-off category, which is recorded on insurance databases and flagged by any vehicle history check. The category determines whether the car can be repaired and returned to the road, and under what conditions.
The Four Write-Off Categories
Cat A — Scrap Only
A Category A write-off is the most severe. The vehicle must be crushed in its entirety — no parts can be salvaged or resold. Cat A is typically assigned to vehicles that have been so severely damaged that even individual components pose a safety risk, or to vehicles that have been involved in fires, floods, or other catastrophic events.
A Cat A vehicle can never legally return to the road. It cannot be repaired, re-registered, or sold for parts. If you ever see a Cat A vehicle being offered for sale, walk away immediately — it is either a fraud or a serious legal issue.
Cat B — Body Shell Must Be Crushed
A Category B write-off means the body shell of the vehicle must be crushed, but certain parts — the engine, gearbox, wheels, and other mechanical components — can be salvaged and resold as spare parts. The vehicle as a whole cannot return to the road.
Like Cat A, a Cat B vehicle should never be offered for sale as a road-going vehicle. Its VIN and registration are permanently retired. If a vehicle shows Cat B on a history check, do not buy it for road use under any circumstances.
Cat S — Structural Damage, Can Be Repaired
A Category S write-off has sustained structural damage — to the chassis, crumple zones, or other load-bearing elements of the vehicle. However, unlike Cat A and B, a Cat S vehicle can be repaired and legally returned to the road.
Before a Cat S vehicle can be re-registered and driven, it must undergo a formal inspection to confirm that repairs have been carried out to the required standard. Once passed, it can be sold and driven legally.
Cat S vehicles are often sold at significant discounts — sometimes 20 to 40 percent below market value for an equivalent undamaged car. This can represent genuine value if the repairs have been done properly. However, structural damage that has been poorly repaired can compromise the vehicle's safety in a subsequent accident — crumple zones may not perform as designed, and the vehicle's geometry may be subtly affected.
If you are considering buying a Cat S vehicle, have it independently inspected by a qualified mechanic or engineer before purchase. Do not rely solely on the fact that it has been re-registered.
Cat N — Non-Structural Damage, Can Be Repaired
A Category N write-off has sustained damage that does not affect the structural integrity of the vehicle — typically electrical damage, cosmetic damage, or damage to non-structural components such as lights, bumpers, or interior fittings.
Cat N vehicles do not require a formal structural inspection before returning to the road, though they should of course be repaired safely. They are typically sold at smaller discounts than Cat S vehicles — often 10 to 20 percent below market value.
Cat N write-offs can represent reasonable value, particularly if the damage was cosmetic and has been properly repaired. The key question is always whether the repairs were done to a professional standard and whether the full extent of the damage was identified and addressed.
The Old Categories — Cat C and Cat D
Before October 2017, the UK used a different categorisation system with four categories — A, B, C, and D. Cat C was broadly equivalent to the current Cat S (structural damage repaired), and Cat D was broadly equivalent to Cat N (non-structural damage repaired).
If a vehicle's history check shows a Cat C or Cat D write-off, this refers to the pre-2017 classification. The principles are the same — Cat C indicated more significant damage than Cat D, and both could legally return to the road after repair.
How to Check if a Car Has Been Written Off
A written-off vehicle's category is recorded on insurance databases and flagged by any reputable paid vehicle history check. The free DVLA check does not reliably return write-off category data.
Run a full vehicle history check before buying any used car. If the check returns a write-off marker — Cat S, Cat N, Cat C, or Cat D — you will be able to see the category and, in some cases, the date of the write-off event.
Read our guide to HPI checks and vehicle history checks for more detail on what each type of check covers.
Should You Buy a Written-Off Car?
The honest answer is: it depends on the category, the quality of the repair, and the price.
Cat A and Cat B — never buy for road use. No exceptions.
Cat S — potentially viable if the repairs have been done to a professional standard and independently verified. Get a specialist inspection. Negotiate a meaningful discount to reflect the write-off history. Understand that some insurers will not cover Cat S vehicles, or will charge significantly higher premiums.
Cat N — more straightforward, particularly for cosmetic damage. Verify the repairs are complete and professionally finished. A discount is reasonable given the history, even if the damage was minor.
In all cases, full disclosure of the write-off history to your insurer is essential. Failing to disclose a known write-off when taking out a policy can invalidate your insurance.
What to Ask When Viewing a Car with a Write-Off History
If you are viewing a vehicle that a history check has identified as a write-off, ask for documentation of the repairs — ideally an invoice from the repair shop, details of any parts replaced, and evidence of the post-repair inspection if applicable for Cat S vehicles.
Ask the seller whether they are aware of the write-off history and whether it was disclosed to them when they purchased the vehicle. Compare the claimed repair work to any visible signs of damage, paint matching, or panel alignment issues.
Misaligned panels, overspray on rubber seals, different paint textures between adjacent panels, or fresh underseal in isolated areas can all indicate previous accident damage that may not have been fully or professionally repaired.
Frequently Asked Questions
Can a Cat S car pass an MOT? Yes. A Cat S vehicle that has been repaired and re-registered can pass an MOT like any other vehicle. The MOT tests roadworthiness at a point in time — it does not assess the quality of previous structural repairs in detail.
Will my insurance be affected if I buy a write-off? Yes. You must disclose a known write-off history to your insurer. Some insurers will decline to cover certain categories, and others will charge higher premiums. Always check before purchasing.
Can the write-off marker be removed from a vehicle's history? No. A write-off category is a permanent record on insurance databases. It will show on any history check regardless of how well the vehicle has been repaired.
Is a written-off car worth less when I come to sell it? Yes. A write-off history will typically reduce the vehicle's value by 20 to 40 percent for Cat S and 10 to 20 percent for Cat N compared to an equivalent undamaged car. This should be reflected in the price you pay when buying.
Key Takeaways
Cat A and Cat B write-offs can never legally return to the road — do not buy them for road use. Cat S indicates structural damage that can be repaired — always get an independent inspection before buying. Cat N indicates non-structural damage — lower risk but still worth verifying repairs. Always run a paid vehicle history check — the free DVLA check does not reliably return write-off data. Disclose any known write-off history to your insurer — failure to do so can invalidate your policy. A write-off history should be reflected in a meaningfully lower purchase price.