The write-off categories, accurately
Since the ABI's Salvage Code of Practice changed in October 2017, insurers grade a written-off car by the type of damage, not just the repair cost. The old Cat C (broadly today's Cat S) and Cat D (broadly Cat N) still appear on cars written off before that date, so you'll see all four letters in older listings.
Catastrophic damage. The whole vehicle must be crushed; not even parts may be salvaged.
Severe damage. Roadworthy parts may be reclaimed, but the body shell must be destroyed and the car can never be re-registered.
Structural damage (chassis, crumple zones, suspension mounts or safety cage). Can return to the road after professional repair and DVLA re-registration. The marker is permanent.
No structural damage — but 'non-structural' can still mean airbags, electrics, water ingress or brakes. Can return to the road after repair; no re-registration required.
Cat S vs Cat N: what's the real difference?
The single line that matters: Cat S means the car suffered structural damage — to the chassis, crumple zones, suspension mounting points or safety cage — that has since been repaired. Cat N means non-structural damage only, with the safety structure intact.
The honest nuance most guides skip: “non-structural” is not the same as “minor.” A Cat N write-off can involve deployed airbags, flood and water damage, or significant electrical faults — all potentially expensive and safety-relevant. The category tells you whether the safety structure was hit, not how serious or well-repaired the damage was.
The honest pros and cons
In favour
- A real discount — often 15–40% below a clean equivalent.
- Cat N damage is frequently cosmetic and fully repairable.
- A well-repaired car can be a sound long-term keeper.
- More car for your budget if you'll hold it for years.
Against
- Higher insurance, and some insurers decline outright.
- Finance is harder to get and may be refused.
- A permanent resale hit — the marker never clears.
- Repair quality is unknown unless you verify it.
What it really costs: insurance, finance and resale
Most guides cover one of these and skip the rest. Here are all three in one place, because the saving only counts after you net them off.
- Insurance. You must declare the category — failing to do so can void a claim. Expect premiums roughly 10–25% higher than a clean car, and occasional refusals. Get a quote on the exact category before buying via your insurer.
- Finance. Many mainstream lenders decline write-off categories because their security is worth less. If you need finance, confirm it's available first — and separately, check the car isn't still on someone else's finance.
- Resale. The marker is permanent. Cat N typically sits 15–30% below a clean equivalent, Cat S around 20–40% — and you inherit the same scepticism when you sell. Treat these as industry estimates, not guarantees; the real figure depends on the model and repair.
How to spot a poorly repaired write-off
The category is only as good as the repair behind it. Whether you view the car yourself or send an inspector, look for:
- Uneven panel gaps or doors and the bonnet that don't line up.
- Paint overspray on rubber seals, or “orange-peel” texture and colour mismatch between panels.
- Mismatched or fresh welds, and new underseal that looks applied to hide a repair.
- Airbag warning lights or a dashboard light that won't clear — a tell after a front-end write-off.
- Damp or musty smells, misted lights and corroded connectors — classic flood-damage signs.
- Uneven tyre wear suggesting the alignment or geometry was never properly reset.
For any Cat S — where the damage was structural — an independent pre-purchase inspection (typically £150–£250 from the AA or RAC) is straightforward insurance against a bodged repair. Ask for the repair documentation and, ideally, photos of the original damage.
What a history check can — and cannot — tell you
A paid provenance check confirms whether a write-off category has been recorded against the car in the insurance industry's MIAFTR register — and sometimes the damage type. That's genuinely useful. But be clear about its limits.
- It cannot tell you the repair quality — only that a category exists.
- A clear result is not a guarantee the car was never damaged. A category is only recorded if an insurer logged a total-loss claim. A privately repaired car, a cash write-off never claimed, or damage abroad may carry no marker at all.
- The official category lives in MIAFTR, not in free DVLA or MOT data — so no free check confirms it. We surface the free signals (MOT, mileage, keeper) and point you to a licensed provider for the category itself.
So, is it worth it? The honest decision rule
Buy a Cat S or Cat N car only if all of these are true:
- The discount is genuinely large versus a clean equivalent — not a token reduction.
- Repair quality is independently verified (especially structural work on a Cat S).
- You'll keep the car long-term, so the permanent resale hit doesn't bite.
- Insurance — and finance, if you need it — are confirmed before you commit.
- The category is S or N (never A or B), with documentation to back it up.
If any one of those fails, walk away — there are plenty of cars. Between the two, Cat N is generally the safer betbecause the safety structure was never compromised; a Cat S demands more proof before it's worth the risk.
Check the car you're considering
Run a free MOT and mileage check on any UK reg, then read up on the exact category on our Cat S / Cat N check page.