Imagine the sickening crunch of metal on metal as your car is rear-ended in heavy traffic. The damage looks superficial but the repair shop winces when you pull up. A few days later your insurance company calls with grim news: your faithful vehicle is a write-off. They assign it a mysterious code - Cat A, Cat B, Cat S or Cat N - and offer a settlement. For most drivers, these letters raise more questions than answers. Are you allowed to keep the car? Can you salvage parts? Should you scrap it? Understanding what each category means can help you navigate the aftermath of an accident and make informed choices about your vehicle's future.

What does "write-off" mean?

An insurance write-off is industry shorthand for a vehicle that has been damaged to the point where it is either unsafe to repair or uneconomical to fix. Assessors compare the cost of returning the car to its pre-accident condition with its market value; if repairs exceed this threshold, the insurer will compensate the owner and take possession of the damaged vehicle. To indicate the severity of the damage and determine what should happen next, insurers apply one of four main categories: A, B, S or N.

Category A - total destruction

Cat A is the most severe classification. A Category A vehicle is beyond repair and never to be driven again; it cannot even be sold for parts and is sent straight to an authorised treatment facility (ATF) to be crushed. These vehicles often come from high-speed collisions or fires that destroy both structure and mechanical parts. If your car is deemed Cat A, you cannot legally retain it; the insurer will handle scrapping and you will receive only the payout.

Category B - parts only

Cat B is slightly less extreme than Cat A, yet still irreversible. These vehicles have sustained extensive damage and can never return to the road, but some components remain safe for reuse. Cat B cars allow the removal of mechanical parts like engines or gearboxes, whereas the body shell must be crushed. In practice, your insurer will arrange for the car to be broken up at an ATF. Owners cannot re-register or drive a Cat B car, but they may have the option to buy back certain parts if the insurer permits.

Category S - structural repairable damage

Cat S (formerly Category C) covers vehicles that have suffered structural damage - the chassis is bent, crumple zones have collapsed or major panels are twisted - but can be repaired to a safe standard. A Cat S car has sustained serious structural damage but can be repaired and driven, although the cost of repair may exceed its value. This damage is more than cosmetic and requires professional repairs; a car with a twisted chassis will not be safe until properly restored. If your car is labelled Cat S, you can sometimes negotiate to buy it back from the insurer. However, you must repair it to a roadworthy condition, submit a V23 form and inform the Driver and Vehicle Licensing Agency (DVLA). Proper documentation is essential to avoid penalties.

Category N - non-structural repairable damage

Cat N (previously Category D) refers to vehicles that have sustained non-structural damage. This could include cosmetic issues like dented panels or broken lights, or mechanical problems like faulty electrics. Cat N cars are considered to have minor, repairable damage. These vehicles have not sustained structural damage, but they may still have safety-related faults such as faulty brakes or steering. Unlike Cat A or B cars, Cat N vehicles can often be repaired and returned to the road, though insurers may decide the repair is uneconomical for them. Buyers should always perform thorough checks and obtain proof of repairs before purchasing a Cat N vehicle.

Why categories matter for scrapping

The four categories guide what should happen to a written-off car. Under the ABI Salvage Code, Category A and B vehicles must be destroyed so they do not re-enter circulation. Insurers typically send these vehicles directly to licensed ATFs, where trained depollution teams drain fluids, remove batteries and neutralise airbags before shredding the metal. This protects the environment and ensures dangerous shells are not sold illegally. For Cat S and N cars, there is a grey area. Insurers may sell them back to the owner or at salvage auctions, but the onus is on the buyer to ensure proper repairs and paperwork.

Your rights and responsibilities

If your car is deemed Cat A or Cat B, your insurer owns the vehicle once you accept the payout. However, you should still keep the "sell, transfer or part-exchange your vehicle" section of the V5C logbook and send the rest to the insurer when required. For Cat S and Cat N write-offs, you may have the right to buy back the vehicle for repair. Some insurers allow owners to purchase their written-off car and fix it at their own expense. If you choose this route, inform the DVLA, obtain a new MOT and retain receipts and photographs of the repairs. Some insurers will insist on an inspection before reinstating comprehensive cover.

There are also potential bargains to be found. Some sellers try to pass off Cat S or N cars as undamaged by hiding their past, so always carry out a vehicle history check. Because insurers use different repair-to-value ratios, minor cosmetic damage can lead to a write-off even if the car is mechanically sound. For careful buyers, this can translate into a cheaper vehicle. For sellers, being honest about the category is not only ethical but also a legal requirement - failing to declare a write-off status can result in fines or prosecution.

Tips for dealing with write-offs

Ask questions: When your insurer declares your car a write-off, ask which category applies and why. Understanding the classification helps you decide whether to buy back the vehicle or accept the payout.

Request a salvage report: For Cat B vehicles, only certain parts may be safe to reuse. A salvage report lists which components are authorised for resale.

Use a licensed ATF: If you decide to scrap the vehicle yourself, choose an authorised treatment facility. They will issue a Certificate of Destruction, confirming that the car has been processed legally. 

Check buyer credentials: If buying a Cat S or N vehicle, confirm that repairs were done by a qualified body shop and obtain evidence. A cheap price may hide expensive future issues.

Inform the DVLA: When transferring ownership of a written-off vehicle, notify the DVLA promptly to avoid penalties.

The bigger picture

Write-off categories may seem bureaucratic, but they serve an important purpose. They protect consumers from unknowingly buying dangerously damaged cars and ensure that scrap vehicles are dealt with responsibly. By separating unrepairable shells from salvageable cars, the system feeds useful parts back into the supply chain while preventing unsafe vehicles from returning to the road. For the environment, it guarantees that hazardous materials are removed before metal is shredded and recycled. For owners, understanding Cat A, B, S and N can turn an upsetting accident into an informed decision about whether to scrap, salvage or walk away. The next time you hear someone lament that their car was "written off", remember that those letters are not just labels - they are a roadmap for what comes next.