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Guide

Cat S, Cat N and Write-Off Categories Explained

By Chi Yung Lee · Updated September 2026

You’ve found a car that looks like a bargain — a few thousand pounds under the going rate. Then you spot two letters in the advert: “Cat N.” Is that a deal-breaker, or a smart buy? A written-off car isn’t automatically a scrap heap — but you need to understand exactly what the category means before you hand over any money.

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Why this matters

An insurance write-off is a car the insurer decided wasn’t economical to repair after a claim — often because the repair cost was high relative to the car’s value, not because the damage was catastrophic. Many written-off cars are repaired and returned to the road perfectly safely. Others hide serious structural damage behind a shiny respray.

Crucially, a write-off record does not appear in the free gov.uk MOT history. A repaired write-off can hold a valid MOT and look flawless. The only way to know is a vehicle history check that includes insurance data.

The four write-off categories

  • Category A (Scrap) — so badly damaged it must be crushed. Nothing may be salvaged, not even parts. It can never legally return to the road.
  • Category B (Break) — the body shell must be destroyed, but some serviceable parts may be reused. The car itself must never return to the road.
  • Category S (Structural) — structural damage (chassis, frame, crumple zones) that has been, or can be, repaired. Legal to drive once properly repaired.
  • Category N (Non-structural) — damage that isn’t structural — panels, lights, electrics or cosmetic. Legal to drive after repair.

A Category A or B car advertised as roadworthy is being sold illegally — those cars must never be driven, and it is worth reporting the advert.

Cat N meaning

Cat N means the insurer wrote the car off for damage that did not affect its structure — panels, lights, bumpers, electrics, interior, or a mechanical failure that cost more than the car was worth to fix. The frame and crumple zones were judged sound.

That makes Cat N the lighter of the two categories a car can come back from, but “non-structural” is not the same as “minor”. A flood-damaged car, or one with a written-off engine, is Cat N too. What matters is what the damage was and how it was repaired.

Cat S vs Cat N side by side

Cat S (Structural)Cat N (Non-structural)
What was damagedChassis, frame, crumple zones, suspension mounting pointsPanels, glass, lights, electrics, interior, mechanical parts
Can it return to the road?Yes, once properly repairedYes, once properly repaired
Re-registrationThe logbook is reissued marked as a salvage vehicleUsually no change to the logbook
Typical questionsWho repaired it, to what standard, was it inspectedWhat exactly was damaged, is anything still outstanding
InsuranceSome insurers decline or ask for an engineer's reportMost insure it; some load the premium
ResaleLower, and the record follows the carLower, and the record follows the car

Legacy Cat C and Cat D

Before October 2017 the categories were based on cost rather than the type of damage. Cat C meant the repair would have cost more than the car was worth; Cat D meant it was repairable but the insurer still chose not to. Neither says anything about whether the damage was structural.

Because the old and new categories measure different things, a Cat C is not simply “an old Cat S” and a Cat D is not “an old Cat N”. The report shows the legacy category exactly as it was recorded rather than translating it, so a pre-2017 write-off reads as Cat C or Cat D with its date.

Insurance on a written-off car

You must declare a write-off category when you insure the car. Some insurers will not cover a Cat S at all, some ask for an independent engineer's report first, and some cover both categories at a higher premium. Practice varies widely, so get a quote for the specific car before you agree a price, not after.

Resale value

A repaired write-off typically sells for somewhere between 20% and 40% less than the same car with a clean record. The pool of buyers is smaller, many dealers will not take one in part-exchange, and you must disclose the category when you sell — it is on the record whether you mention it or not. Pay a write-off price when you buy, and expect one when you sell.

How it appears in the report

The Full History Report shows the category as the insurer recorded it, with the date. Where a salvage auction listing describes the car differently from the insurer — an auction label of Cat N against an insurer record of Cat S, say — the insurer's category is what the report shows, and the auction record appears separately. The report describes what the record holds; it does not tell you whether to buy.

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Should you buy a Cat S or Cat N car?

It can be a genuine bargain — but only with your eyes open. Before buying a repaired write-off:

  • Ask for repair evidence — photos of the original damage, receipts, and who carried out the work. No paperwork is a red flag.
  • Get an independent inspection — a repaired Cat S car especially should be checked by a qualified engineer.
  • Budget for lower resale value — a write-off record follows the car forever and reduces what you’ll get when you sell.
  • Check insurance first — some insurers charge more, or decline the car entirely. Get a quote before you commit.

⚑ Red flags checklist

  • The seller doesn’t mention the write-off at all (check it yourself before viewing)
  • No repair receipts or evidence of who did the work
  • A Cat S car with no independent inspection offered
  • Panel gaps, mismatched paint, or overspray on rubber seals and trim
  • A price that’s “too good” with no clear explanation

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Frequently asked questions

Is it safe to buy a Category S or Category N car?+
It can be, if the repair was done properly and documented. Category S means structural damage was repaired; Category N means non-structural damage. Both are legal to drive and sell once repaired, but you should insist on repair evidence and, for a Cat S car especially, an independent inspection.
What is the difference between Cat S and Cat N?+
Cat S (Structural) means the damage affected the car’s structure — the chassis, frame or crumple zones — and was repaired. Cat N (Non-structural) means the damage was cosmetic or to parts like panels, lights or electrics. Cat S is generally the more serious of the two.
Does a write-off show up on the free MOT check?+
No. Insurance write-off records aren’t part of the MOT data, so a repaired write-off can hold a valid MOT and look perfect. You need a check that includes insurance write-off data — that’s part of the AI Plate Checker full history report.
Can a Cat A or Cat B car be driven?+
No. Category A cars must be crushed entirely and Category B cars must have their body shell destroyed — neither may ever return to the road. If one is advertised as roadworthy, it is being sold illegally and is worth reporting.
Is Cat N worth buying?+
It can be, at the right price and with the repair documented. Cat N damage was non-structural, so the car's frame was judged sound, but you should still see what was damaged, who repaired it, and get an insurance quote before you commit.
Can a Cat S be made un-Cat S?+
No. Once an insurer records a category it stays on the vehicle's record permanently, even after a full repair and inspection. A seller who says the category has been removed is mistaken or misleading you.
Does “Category Stolen” mean Cat S?+
No. Category Stolen is an insurer's theft-related marker used when a stolen car was paid out on and later recovered. Cat S means structural damage. They are separate records and can both appear on one car.

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