Cat N and Cat S: what car write-off categories mean

A cheap car with "Cat N" or "Cat S" in the advert can look like a bargain. Sometimes it is. But it means an insurance company has already decided the car was not worth repairing after damage, so you need to know what happened and how well it was put right.

What "written off" means

According to GOV.UK, when a car is written off the insurance company pays the owner the car's current value instead of the cost of repairing it. The insurer decides whether a car is written off, and puts it in a category.

The four write-off categories

• Category A: cannot be repaired. The entire vehicle has to be crushed.
• Category B: cannot be repaired. The body shell has to be crushed, but other parts can be salvaged.
• Category N: can be repaired following non-structural damage, and used again once it is repaired to a roadworthy condition.
• Category S: can be repaired following structural damage, and used again once it is repaired to a roadworthy condition.

So a Cat A or Cat B car should never be back on the road as a whole car. If you are offered one, walk away. Cat N and Cat S cars can legally be repaired and sold, and those are the ones you will see in adverts.

How to find out if a car has been written off

GOV.UK says that when an owner keeps a Category S car, they must send the log book to the insurer and apply for a duplicate on form V62, and DVLA records the category in the log book. An owner keeping a Category N car can keep the existing log book.

That is why the log book alone is not enough. Citizens Advice recommends a private history check, which it says costs up to £20, and which will tell you if the car has been written off, repaired and returned to the road. Do it before you hand over any money, whatever the seller tells you.

Cat N or Cat S: what to check before you buy

From the trade, these are the questions that matter most on a repaired write-off:

• What was the damage? Ask for photos from before the repair and the insurer's or assessor's notes if the seller has them.
• Who repaired it? A proper bodyshop invoice listing the parts used is worth far more than "my mate did it".
• Does the car look straight? Uneven panel gaps, paint that doesn't quite match, overspray on rubbers and seals, and tyres wearing unevenly can all point to a rushed repair.
• Has anyone independent looked at it? Citizens Advice says an independent report from a motoring organisation or specialist costs around £120 to £250. On a Cat S car, where the damage was structural, that money is well spent.
• Can you insure it? Get a quote before you buy, telling the insurer the car's category. Do not assume your normal premium will apply.

Is a Cat N or Cat S car a good buy?

It can be, if the price reflects the history and the repair was done properly. The trade view is simple: a written-off car is usually worth less than the same car without that history, and it will be worth less when you sell it too, so the discount has to be big enough to cover both. A Cat N car with light, well-documented cosmetic damage is a very different proposition from a Cat S car with an unknown repair history.

If you are not sure, walk away. There will be another car. Read our guides to V5C log book checks and checking MOT history next, or grab the free 10-point checklist.

Facts in this guide are taken from GOV.UK and Citizens Advice, linked above, and were checked on 17 October 2026. Rules change, so always check the official source before you buy. This is general information, not legal advice.