Blog / Write-off categories

Buying · 5 min read

What Is a Cat S, Cat N, or Cat B Write-Off?

If a car has been in a serious accident, an insurer may declare it a write-off rather than repair it. That doesn't automatically mean it's scrap. Since October 2017, the UK uses four categories, and two of them describe cars that can legally go back on the road.

The four categories

• Cat A is the most severe. The entire vehicle must be crushed, including parts that would otherwise be reusable. A Cat A car can never legally return to the road.
• Cat B means the body shell must be crushed, but mechanical parts like the engine and gearbox can be salvaged and sold separately. Like Cat A, the vehicle itself can never be driven again.
• Cat S means structural damage, such as a bent chassis or damaged crumple zone. Unlike A and B, a Cat S car can be repaired and legally driven again once the repair is complete and the vehicle is re-registered with the DVLA.
• Cat N means non-structural damage, such as bumpers, electrics, or airbags. Cat N cars can also return to the road once repaired, and generally don't need DVLA re-registration first.

Cat S and Cat N replaced the older Cat C and Cat D system in October 2017. Cars categorised before that date keep their original C or D label permanently, so both systems still appear on older vehicles' records.

Why the category matters if you're buying

A Cat S or Cat N marker doesn't automatically mean a car is a bad buy. It means the vehicle needs to be judged on the quality of its repair rather than taken at face value. A well-repaired Cat N car with proper documentation can be a reasonable purchase at a discounted price. A poorly repaired Cat S car with structural work done cheaply is a genuine safety risk, and the category alone won't tell you which one you're looking at.

Practically, this means asking for repair invoices, checking that a Cat S car was formally re-registered with the DVLA after the work, and budgeting for a specialist inspection if the price seems unusually low for what's on offer. It's also worth knowing that write-off history typically pushes insurance premiums higher, which is worth factoring into the real cost of ownership rather than just the purchase price.

What free checks can and can't tell you

Write-off category isn't held in the free DVSA or DVLA records, since it's insurance industry data rather than government data, so a free MOT and tax check won't reveal it on its own. What it will show is the mileage and condition trail across MOT tests, which is still useful context: a car that's had unusually large repair-related gaps between tests, or advisories that don't match its stated history, is worth asking more questions about regardless of write-off status.