"Write-off" sounds terminal, but most written-off cars are back on the road within months: repaired, retested and resold. Some are genuinely good buys. Some are structural repairs done to a price in a hurry. The category letter is where you start telling them apart.

What a write-off actually is

A car gets written off when an insurer decides repairing it costs more than it's worth to them, which, crucially, is an economic judgement, not a mechanical one. A ten-year-old hatchback worth £2,500 can be written off by a scraped door and a dented wing, because bodyshop labour plus paint plus a courtesy car exceeds £2,500 before anyone touches a structural component. The insurer pays out, takes the car, and sells it into the salvage trade. Where it goes from there depends on the category.

The four categories

Since October 2017 there have been four, and the split that matters is structural versus not:

  • Cat A: scrap. Too damaged to yield anything. The whole car must be crushed, parts included. It should never reappear.
  • Cat B: break for parts. The body shell must be destroyed, but undamaged parts can be sold on. A Cat B car back on the road is illegal, full stop.
  • Cat S: structural damage, repairable. Something load-bearing (chassis leg, crumple zone) was damaged. It can legally be repaired and driven again, but it must be re-registered with DVLA first, and the S marker stays on its record for life.
  • Cat N: non-structural. Everything else: cosmetic panels, lights, interior, electronics. No DVLA re-registration needed. Don't read "non-structural" as "minor", though: steering, brake and suspension damage can all be classed Cat N.
The four insurance write-off categories A, B, S and N in order of severity - Cat A and Cat B can never return to the road, Cat S and Cat N are road-legal after repair
The four categories since October 2017.

Cars written off before October 2017 carry the old letters: Cat C (roughly equivalent to S) and Cat D (roughly N). You'll still meet plenty of them in the classifieds.

The part that catches buyers out

Here's the uncomfortable bit: a write-off marker doesn't reliably show on the logbook. Cat S should be noted on the V5C, but Cat N often isn't, because insurers don't always tell DVLA about non-structural claims. The marker lives in the insurance industry's own salvage register, which is why a car can look completely clean on its paperwork and still be a former write-off, and why the seller saying "not that I know of" can even be true. The marker doesn't expire, either. It follows the car forever, and it resurfaces the moment the next buyer runs a proper salvage check, usually right when you're trying to sell.

Should you ever buy one?

Sometimes, genuinely, yes: with eyes open and at the right price. A Cat N that was written off for a bumper, a headlight and a parking sensor, repaired with photographs to prove it, is a lot of car for the money. The trade discount is roughly 20–30% off clean-car value for Cat N and 30–40% for Cat S, and that discount never goes away; you give it back when you sell.

The rules of engagement:

  • Price it as marked. A Cat N priced like a clean car has no upside for you at all.
  • Demand the repair story. Photos of the damage, invoices for the work, who did it. "Professionally repaired" with no evidence means nothing.
  • Cat S: check the paperwork trail. It should have been re-registered after repair, and an independent inspection (£150–£250) is money well spent on anything structural.
  • Ask in writing. "Has this car ever been written off or recorded as salvage?" It's a one-line message that becomes very valuable if the answer turns out to have been a lie. A dealer who knowingly hides a marker is breaking consumer protection law.
  • Tell your insurer. Insuring a former write-off is normal and usually barely dearer, but failing to declare it when asked can void the policy.

How this fits into checking a car

Treat the write-off question as one thread in the same fabric as everything else: does the MOT history show a gap around a suspicious date? Did the mileage line hiccup at the same time? Does the paint tell a different story from the ad? A history check pulls the recorded threads together (spec, MOT record, mileage trend, scrappage and export markers) and the physical inspection covers the rest. A car that's clean on every thread is almost never hiding a big one.