Every guide to write-off categories tells you what the letters stand for and then leaves you exactly where you started, staring at a car that's £3,000 cheaper than everything else and wondering whether that's a bargain or a trap.
The letters are the easy part. Here's the bit that decides it.
What do Cat N and Cat S actually mean?
Both mean an insurer decided the car wasn't economical to repair and paid out on it. The letter tells you what kind of damage caused that decision.
Cat S is structural. The chassis, crumple zones, suspension mounts or other safety-critical structure took damage. It can be repaired properly and returned to the road, but it has to be re-registered with the DVLA before it goes back on.
Cat N is non-structural. The shell is sound and the damage was somewhere else. That sounds reassuring and often is, but non-structural still covers brakes, steering, airbags and electrics, so a Cat N is not automatically a scraped bumper.
| Category | What it means | Back on the road? |
|---|---|---|
| Cat A | Scrap only. The whole car is crushed, no parts saved | Never |
| Cat B | Shell is crushed, usable parts may be salvaged | Never |
| Cat S | Structural damage, repairable | Yes, after DVLA re-registration |
| Cat N | Non-structural damage, repairable | Yes, no re-registration needed |
The important thing nobody leads with: the marker is permanent. Repair it beautifully, drive it for nine years, sell it in perfect condition, and it's still a Cat S. That's the fact that drives everything below.
What about Cat C and Cat D?
Those are the old names, used before the categories changed on 1 October 2017. You'll still meet them, because the marker stays with the car for life and plenty of pre-2017 cars are still being sold.
Roughly, Cat C is the old equivalent of Cat S and Cat D of Cat N, but they were defined by repair cost rather than damage type, so the mapping isn't exact. Cat D in particular could mean almost nothing was wrong: the insurer just decided repairing it wasn't worth the bother. Two cars with the same letter can be in wildly different states.
Is a Cat S or Cat N car safe to buy?
It depends entirely on the repair, and the repair is the thing nobody can show you from an advert.
A Cat S repaired by a competent bodyshop, on a jig, with the geometry set properly afterwards, is a sound car. A Cat S straightened in a yard by eye is not, and it will never quite drive right, wear its tyres evenly or crash the way it was designed to. The category doesn't tell you which one you're looking at. The paperwork does.
Two things worth knowing before you get reassured by the obvious:
An MOT proves very little here. A repaired write-off can pass an MOT comfortably. The test isn't an inspection of repair quality, and it can't tell whether a structural repair restored the car's designed strength.
A Cat N can be sold still broken. There's no requirement to repair a Cat N before selling it on, and plenty go through salvage auctions and straight into private adverts unrepaired. "Cat N, drives fine" deserves a proper look underneath.
Check the history before you hand over money
A Provenance Check covers the four things no free lookup includes: outstanding finance, theft markers, insurance write-off category and recorded mileage discrepancies.
Run a provenance check →How much less should you pay for one?
The figure usually quoted is 20 to 40 percent below a clean example, with Cat S at the deeper end and Cat N nearer the shallow one. Treat that as the starting point, not the answer.
The mistake buyers make is treating the discount as free money. It isn't, because you take the same discount again when you sell. If you pay 25 percent under book for a Cat S and sell it three years later, you're selling a Cat S too, into the same suspicion you had. The discount isn't a saving, it's the price of an asset that's permanently worth less.
That still adds up if you're keeping the car a long time and it was repaired properly. It adds up much less if you change cars every two years.
What does it do to insurance and finance?
Both, and this is where people get caught after the deal rather than before it.
You have to declare it. Every insurer asks, and not telling them can void the policy, which is a considerably worse outcome than a higher premium. Some insurers won't quote at all on a Cat S, others load the premium, and some don't mind. Get quotes before you buy, not after.
Some lenders won't finance one. If you're planning to borrow against the car, check the lender's position on write-off categories first. Finding out at the point of signing is a bad afternoon.
A written-off car can be written off again more easily. It starts from a lower value, so a smaller repair bill exceeds it. The discount you enjoyed on the way in works against you the next time something happens.
How do you find out whether a car is a write-off?
Not from a free check, which is the part that catches people.
Write-off categories are recorded on the insurance industry's claims and theft register, not by DVLA. So the free DVLA and MOT checks will show a Cat S as taxed, MOT'd and completely unremarkable. There's no flag, no note, nothing. It takes a provenance check to see it.
Sellers know this. A Cat car advertised without the category mentioned is not necessarily dishonest, plenty of private sellers genuinely don't know, but it does mean the burden of finding out sits entirely with you.
What should you ask before buying one?
If you're seriously considering a Cat S or Cat N, get these answered before any money moves:
- Which category, and what was the damage? A straight question. Vagueness here is the answer.
- Who did the repair, and where's the invoice? A named bodyshop with a bill is the whole difference between a repaired car and a hidden one. No paperwork, no deal.
- Was the geometry checked afterwards? On a Cat S this is not optional. Ask to see it.
- Can an independent inspection go over it? A refusal tells you everything. If they agree, this is the money best spent in the whole process.
- What do three insurers quote? Do this before you commit, not after.
- What else does this model do anyway? A write-off doesn't cancel out the car's own weaknesses, it stacks on top of them. Worth reading up on the Golf or Focus or whatever you're looking at, so you're not budgeting for one problem while a known one waits.
Cat cars are genuinely one of the few places a careful buyer can do well, because most people won't touch them and the discount is real. That only works when you can see the repair, though. Buy the paperwork, not the letter, and read the advert wording carefully while you're at it. If the category never comes up at all, that's worth a question on its own.
Where to start on a specific car
Run a free scan on it before you go anywhere. It reads the advert against that car's MOT history and the faults the model is known for, so you'll see whether the advert is being straight with you and what the car does anyway, independently of any repair.
The category itself needs the Provenance Check, because write-off records sit on the insurance industry's register and no free source carries them. It's an upgrade on the same report with nothing to re-run, so the order that makes sense is free first, then the provenance lookup once you've decided a car is worth pursuing. On a Cat car that lookup is the difference between knowing the letter and taking the seller's word for it, and the seller may genuinely not know either.
