Write-Off Categories Explained

An insurance write-off is a car that an insurer has decided is too expensive to repair after an accident, theft, or other damage. The categories – A, B, S, and N – tell you how severe the damage is and whether the car can ever legally return to the road. Only Cat S and Cat N cars can be repaired and driven again, but they carry a permanent marker that affects value and insurance. Knowing what each category means is the difference between buying a safe, usable car and buying a liability.

What does it mean when a car is written off?

When a car is damaged, the insurer compares the repair cost with the car's pre-accident value. If repairs cost more than the car is worth – typically around 60-70% of its value – the insurer declares it a total loss, or write-off. They pay you the market value and take ownership of the car. The car is then given a category based on the type and extent of damage.

It is important to understand that a write-off marker is not just about cosmetic damage. It is a legal status recorded against the vehicle's identity, and it stays with the car for life. Even if the car is fully repaired and passes an MOT, the marker remains on its history.

What are the four write-off categories?

The categories are set by the Association of British Insurers (ABI) and are used across the UK. They are split into two groups: those that can never return to the road (A and B) and those that can be repaired and re-registered (S and N).

Cat A – Scrap only

Cat A is the most severe category. The car is so badly damaged that it is only fit for scrap. The entire vehicle, including all parts, must be crushed. You will never see a Cat A car for sale as a whole vehicle, because it is legally required to be destroyed. If you come across one, it is almost certainly being sold illegally.

Cat B – Body shell crushed

Cat B means the car's body shell has suffered severe structural damage and cannot be repaired. The shell must be crushed, but some mechanical parts – like the engine or gearbox – may be removed and sold separately. You cannot buy a Cat B car to repair and drive. If you see a Cat B car advertised as a complete vehicle, walk away.

Cat S – Structural damage

Cat S (previously Cat C) covers cars with structural damage that is repairable. This includes damage to the chassis, suspension mounts, or the main body shell. A professional repairer can fix it, and the car can be put back on the road. However, the repair must be done to a high standard, and the car must pass an MOT before it can be driven legally.

Cat N – Non-structural damage

Cat N (previously Cat D) is for cars with non-structural damage. This means the damage does not affect the car's structural integrity. It could be cosmetic – like a dented door or a cracked bumper – or it could involve mechanical parts that are not part of the structure, such as a damaged radiator or air conditioning condenser. Cat N cars can be repaired and returned to the road.

Which categories can legally return to the road?

Only Cat S and Cat N cars can be repaired and legally driven again. Cat A and Cat B cars cannot. If you buy a Cat S or Cat N car, you must ensure it is properly repaired and passes an MOT before you drive it on public roads. There is no requirement to re-register the car or apply for a new V5C, but the marker stays on the vehicle's history permanently.

It is worth noting that a Cat S or Cat N car does not need a special inspection beyond the standard MOT. However, a thorough independent inspection by a qualified mechanic is strongly recommended before you buy, because the quality of repairs varies enormously.

How does a write-off marker affect value and insurance?

A write-off marker significantly reduces a car's resale value. As a rough guide, a Cat S or Cat N car can be worth 20-40% less than an equivalent car with a clean history, depending on the severity of the damage and the quality of the repair. Some insurers may refuse to cover a previously written-off car, or they may charge a higher premium. Others will cover it but may offer a reduced payout if it is written off again.

You must declare a write-off marker to your insurer. If you do not, your insurance could be invalidated, which could leave you with no cover and potentially a fine or prosecution. The marker is recorded on the Motor Insurance Anti-Fraud and Theft Register (MIAFTR), which insurers check.

Is a repaired Cat S or Cat N car safe?

A properly repaired Cat S or Cat N car can be as safe as any other car. The key is the quality of the repair. A reputable repairer will use new or manufacturer-approved parts and follow the vehicle manufacturer's repair methods. A poor repair – one that uses second-hand parts of unknown condition or that does not address structural alignment – can leave the car unsafe in a subsequent collision.

Before buying a repaired write-off, ask to see the repair invoice and any photographs of the damage. If the seller cannot provide evidence of the repair, treat that as a red flag. It is also wise to have the car inspected by an independent mechanic who specialises in accident damage.

How do I find out if a car has a write-off marker?

You can check if a car has a write-off marker by using a vehicle history check service. Our free check uses DVLA and DVSA data, but it does not include write-off markers on the free tier. For a full history check that includes write-off categories, you would need a paid service. We are working on offering a paid write-off check, but it is not yet available.

In the meantime, you can ask the seller for the V5C and check the vehicle's MOT history using our MOT history check. While MOT history does not show write-off markers, it can reveal gaps in testing or suspiciously low mileage that might indicate a repaired car. You can also check if the car is currently taxed using our car tax check.

What should I ask a seller before buying a Cat S or Cat N car?

If you are considering a previously written-off car, ask the seller these questions:

• What category was it – S or N?
• When was it written off, and why?
• Who did the repair, and can I see the invoice?
• Were new or used parts used?
• Has it passed an MOT since the repair?
• Can I have it inspected by my own mechanic?

A honest seller will be open and provide documentation. If the seller is vague, avoids questions, or cannot show proof of repair, walk away. There are plenty of clean cars on the market, and the risk is not worth it.

When is a write-off worth buying, and when should you walk away?

A Cat N car with minor cosmetic damage that has been repaired properly can be a good value purchase, especially if you are happy to accept the reduced resale value. A Cat S car can also be a bargain, but only if the repair is verifiable and the price reflects the marker. You should walk away if:

• The seller cannot provide repair documentation.
• The repair looks poor – misaligned panels, uneven gaps, or overspray.
• The car has a Cat A or Cat B marker.
• The price is not significantly lower than a clean equivalent.
• You cannot get insurance at a reasonable cost.

Before you commit, run a combined MOT and tax check to confirm the car's current status. And if you are buying from a private seller, consider a finance check to ensure there is no outstanding loan on the vehicle. A write-off marker is not the end of the world, but it demands caution and due diligence.