What a write-off actually is
A car is “written off” when an insurer decides it isn't worth repairing: either because the damage makes it unsafe ever to return to the road, or simply because the repair would cost more than the car is worth. That second point surprises people. On an older, low-value car, a dented door and a scuffed bumper can be enough to write it off, so a write-off marker is not automatically evidence of a serious crash.
When a car is written off, the insurer assigns it a salvage category describing the damage. Since October 2017 the categories have been A, B, S and N, defined by an industry salvage code of practice. The category then follows the car for life, which is exactly why it matters when buying used.
The four categories
- Cat A (scrap): so badly damaged the entire vehicle must be crushed, including every part. Nothing from it should ever be reused. It can never legally return to the road.
- Cat B (break): the body shell must be crushed, but undamaged parts can be stripped and sold. The car itself can never legally return to the road.
- Cat S (structural): the car suffered structural damage, to the chassis or crash structure, but can be professionally repaired and put back on the road. The DVLA must be told a car is a Cat S write-off, and it needs to be re-registered before being used again.
- Cat N (non-structural): the damage didn't affect the structure: think body panels, lights, interior or electrics. It can also return to the road. Don't read “non-structural” as “cosmetic”, though: brakes, steering and suspension parts can all be involved in a Cat N marker.
Cat S and Cat N in practice
A repaired Cat S or Cat N car can be perfectly good, and it will usually be priced well below an equivalent clean car, often by 20–40%. That discount exists for reasons, and they don't go away when you buy:
- Repair quality is everything, and mostly invisible. There is no mandatory government inspection of the repair before a Cat S or N car returns to the road, so you are trusting whoever fixed it. Ask for photos of the damage and invoices for the repair; walk away if the seller has neither.
- Insurance can cost more. Some insurers charge more for written-off cars, some won't cover them at all, and payouts after a future claim will reflect the reduced value. Get a quote before you buy, not after.
- The marker never comes off. When you sell, you'll face the same discount you enjoyed, and a smaller pool of buyers.
- An independent inspection earns its fee here more than on any other purchase: a professional can spot poor crash repair (filler, misaligned panels, non-matching paint, welding) that a test drive never will.
The older Cat C and Cat D
Cars written off before October 2017 carry the older categories: Cat C (repair cost exceeded the car's value) and Cat D (repairable, but uneconomic once other costs were counted). They're roughly the ancestors of S and N, but they were defined by repair cost rather than by the type of damage, so a Cat C isn't necessarily structural, and a Cat D isn't necessarily minor. On an older car, treat either the same way as an S or N: judge the repair, not the letter.
Protecting yourself as a buyer
Here's the uncomfortable part: write-off status does not appear in the free MOT and tax data. A car can show a spotless MOT history and a steadily climbing mileage record and still be a repaired Cat S. A dealer must tell you if a car is a recorded write-off; a private seller may simply not mention it. So:
- Run the free checks first: the reg check confirms the car's identity and history, and a big gap in the MOT record around a plausible accident date is itself a clue.
- For any car you're serious about, pay for a provenance check that covers write-off markers, outstanding finance and theft. It costs a few pounds against a purchase of thousands.
- Ask the seller directly, in writing, whether the car has ever been written off. A lie in a message is evidence; a verbal “not that I know of” is nothing.
- If a price looks too good against the rest of the market, a write-off marker is one of the most common explanations.