Around one in five used cars listed on UK forecourts carries an insurance write-off marker. That does not necessarily mean the car is dangerous — but it always affects what the car is worth, and it is not always obvious from the advert.
What actually happens when a car gets written off
When a car gets damaged — whether that is an accident, a flood, a fire, or even a theft recovery — the insurer weighs up the repair cost against what the car is worth. If fixing it costs more than they think the car is worth, they write it off. They pay out the claim, take the car, and sell it on as salvage.
A write-off does not mean the car was destroyed. It means the repair cost exceeded what the insurer valued the car at. A £500 dent on a £2,000 Fiesta gets written off. The same dent on a £30,000 BMW gets repaired without question.
The car gets assigned a category based on how bad the damage was, and that category stays on its record for life.
What the categories mean
The ABI (Association of British Insurers) runs the classification system. It changed in October 2017, so you will see two sets of letters depending on when the write-off happened.
| Category | What it means | Back on the road? | Old system |
|---|---|---|---|
| A — Scrap | Total loss. The whole car must be crushed, parts and all. | No. | Cat A |
| B — Body Shell | The shell gets crushed, but usable parts (engine, gearbox, wheels) can be stripped and sold. | No. | Cat B |
| S — Structural | Damage to the chassis, frame or crumple zones. Can be repaired, but it needs specialist work. | Yes, once repaired and re-registered with the DVLA. | Cat C |
| N — Non-structural | Panels, bumpers, lights, electrics — no frame damage. Easier to repair properly. | Yes, once repaired and re-registered. | Cat D |
Cat A and B cars are gone for good. If you are looking at used cars, you are dealing with Cat S and Cat N.
One thing worth knowing: Cat N does not mean "barely damaged". It means the structural frame was not affected. A car can have £4,000 of panel and electrical damage and still be classified Cat N. The category tells you where the damage was, not how expensive it was to fix.
If the car was written off before October 2017, you will see Cat C (now Cat S) or Cat D (now Cat N). The old system was based on repair cost vs value rather than structural vs non-structural, but in practice they map across fairly well.
How to actually check
There is no free way to check whether a car has been written off. The DVLA's free vehicle enquiry service shows tax and MOT status, but it does not show write-off markers. The free MOT history check does not show them either.
The only way to confirm a write-off marker is through a paid vehicle history check. These query the MIAFTR (Motor Insurance Anti-Fraud and Theft Register), which logs every insurance write-off. The result includes the category, the date, and usually the insurer. HPI, the AA, the RAC, and Get Car Wise all access this database. Prices range from around £5 to £20 depending on the provider.
There are a few things visible for free that can indicate a write-off. Gaps in the MOT history — where the car was off the road for months — sometimes coincide with a repair period after an incident. MOT advisories mentioning misaligned headlights or uneven tyre wear can point to accident damage. A V5C logbook showing the car was briefly registered to an insurance company or a salvage dealer is another indicator. None of these are proof on their own, but they are common patterns seen on written-off vehicles.
What it does to the value
A write-off marker knocks money off a car permanently. How much depends on the category, the age of the car, how well the repair was done, and whether there is paperwork to prove it.
| Category | Typical reduction | Why |
|---|---|---|
| Cat N | 10 – 25% | Non-structural. A well-documented repair on a newer car might only lose 10-15%. |
| Cat S | 20 – 40% | Structural damage makes buyers and insurers nervous. Harder to finance, too. |
| Cat C / Cat D (old) | 10 – 35% | Roughly maps to Cat S / Cat N. Older write-offs tend to matter less. |
To put some numbers on it: a 2019 Ford Focus that would normally be worth £12,000 with a Cat N marker will probably sell for £9,000–£10,800. With Cat S, more like £7,200–£9,600.
The biggest factors are the paperwork and the age of the write-off. A Cat N from five years ago with full repair invoices from a proper bodyshop barely matters. A Cat S from last year with no documentation is a much harder sell.
Performance and prestige cars tend to lose more, because buyers in that market are particularly wary of hidden issues. And some insurers charge significantly more to cover previously written-off cars, which compounds the problem at resale.
Cat N vs Cat S — what buyers are actually getting
Cat N means no structural damage. The car is mechanically the same as one without a marker, provided the repair was done to standard. On newer cars, a bumper replacement or a couple of new panels can be enough to trigger a write-off that looks more serious on paper than the damage actually was. These cars typically sell at a 10–20% discount.
Cat S involves structural damage — chassis rails, crumple zones, subframes. Even a competent repair may not fully restore the car's original crash protection geometry. There is no mandatory independent inspection before a Cat S car goes back on the road. The DVLA requires a V23 form and a fresh MOT, but the MOT does not specifically assess the quality of structural repairs.
Worth knowing: there is no legal requirement for a Cat S car to pass a structural inspection before returning to the road. The standard MOT does not assess accident repair quality. Independent engineer inspections exist but are not compulsory.
Common signs of a previous write-off
These are the physical indicators that body repair professionals and vehicle inspectors typically look for:
Panel gaps. The gaps between doors, bonnet and boot lid are even and consistent on an undamaged car. Uneven panel gaps are one of the most common signs of previous bodywork repair.
Paint overspray. Fresh paint found on rubber door seals, trim pieces inside the door frames, or edges under the bonnet indicates panels have been resprayed. Overspray on surfaces that were not meant to be painted points to masking that was not done to a high standard.
Tyre wear. Uneven wear across the front tyres — particularly one side wearing faster than the other — can indicate that the suspension geometry has shifted, which sometimes results from structural repair work.
Repair invoices. Cars that were repaired professionally typically come with documented invoices from the bodyshop. The presence or absence of repair documentation affects both the car's resale value and buyer confidence.
Insurance and finance. Some insurers will not cover Cat S cars. Most lenders will not finance them. Cat N is more widely accepted by insurers and lenders, but policies often carry higher premiums or rates.
Your rights if a dealer does not disclose it
Under the Consumer Rights Act 2015, a dealer is required to disclose material information that a reasonable buyer would want to know. A write-off marker falls into that category. If a dealer sells a car without disclosing a known write-off, the buyer has grounds to reject the car and claim a refund.
Private sales are different. There is no legal obligation for a private seller to volunteer a write-off marker unless specifically asked. The only way to confirm it in a private sale is to run a paid vehicle history check before the purchase.
Check any car before you buy
Get Car Wise reports include write-off status, full MOT history analysis, known faults for the specific model, mileage verification and a personalised buying checklist.
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Useful links
- DVLA Vehicle Enquiry Service — free tax/MOT status check (does not show write-offs)
- Check MOT History — free MOT records from DVSA
- V23: Register a Rebuilt Vehicle — DVLA form for getting Cat S/N back on the road
- ABI Salvage Code of Practice — the official category definitions
- Consumer Rights Act 2015 — your rights when buying from a dealer