If a car's write-off category looks wrong, such as an advert saying Cat N while the insurance record says Cat S, do not rely on the seller's word. Ask for the paperwork, check the vehicle's registration against independent records, and be ready to walk away if the story does not add up. UK write-off categories are letters, not numbers, so a mismatch is often down to old and new labels being confused, but it can also be a warning sign.
What the Cat letters actually mean
Since October 2017, UK insurers record write-offs on the MIAFTR database using four categories:
- Cat A: scrap only. The vehicle must be crushed and cannot go back on the road.
- Cat B: break only. The shell must be crushed, but usable parts can be sold.
- Cat S: structurally damaged but repairable. The frame or chassis has been affected.
- Cat N: non-structural damage, repairable. Think electrical, cosmetic or bolt-on damage.
Cat A and B cars should not be on sale as roadworthy vehicles, so any advert for one of these as a drivable car deserves serious suspicion.
Why the category might look wrong
There are several common reasons for a mismatch, and not all of them are dishonest.
- Old categories: before 2017 the system used Cat A, B, C and D. Cat C and Cat D no longer exist for new write-offs. Cat C roughly maps to today's Cat S, and Cat D roughly maps to Cat N, but the match is not exact. Sellers often quote the old letter on older write-offs.
- Seller error: some private sellers simply do not know the difference between S and N, or were told the wrong thing when they bought the car.
- Deliberate misdescription: a car may be advertised as Cat N when it is really Cat S, or with no category mentioned at all, to protect the price.
- Wrong registration or cloned plates: if the registration on the advert or V5C does not match the car in front of you, the record you are reading may belong to a different vehicle.
- Typing mistakes: a single wrong character in a registration can bring up a different car, so always check the make, model, colour and fuel type match.
How to check you have the right category
Start with the basics, then verify independently.
- Ask the seller directly whether the car has ever been declared an insurance write-off, and ask for any insurer letters, repair invoices and photos.
- Check the V5C logbook. A write-off should usually be recorded and the keeper details should match the seller. A missing or newly issued V5C is worth asking about.
- Run a vehicle history check using the registration. A check on motorpeek.com can show whether an insurance write-off marker is recorded, alongside MOT history, mileage readings, stolen marker, outstanding finance and previous keepers.
- Compare the MOT history. Gaps, big mileage jumps or repeated advisories about corrosion or structural repairs can hint at past damage that the advert does not mention.
- Check the VIN on the windscreen, the body and the paperwork. They should all match.
No check can promise to catch every issue. Some accidents are never claimed through insurance, and some write-offs may not appear if the vehicle was dealt with outside the usual process. That is why a physical inspection still matters.
What to do if the details do not match
Pause the purchase. If the advert says one thing and the records say another, ask the seller to explain in writing. A genuine mix-up, such as quoting an old Cat D that is now treated as Cat N, should be easy to clear up with documents.
If the seller gets defensive, cannot produce evidence, or the registration and VIN do not line up, walk away. For a car bought from a dealer, you may have rights under the Consumer Rights Act if the vehicle was not as described, and Citizens Advice or Trading Standards can explain your options. For private sales, your protection is weaker, so checking first is far better than arguing afterwards.
Does a Cat S or N car mean a bad buy?
Not automatically. Plenty of Cat S and Cat N cars have been repaired properly and used without trouble. But they usually sell for less, some insurers charge more or decline to cover them, and resale can be harder. A Cat S repair deserves particular scrutiny, ideally with an independent inspection by a qualified mechanic or engineer. What matters is that you know the true category before you agree a price, not after.
Key takeaway
Write-off categories are letters, and the labels changed in 2017, so confusion is common. Treat any mismatch as a reason to check the facts, not as something to brush aside. Verify the registration, VIN and paperwork, and only buy once the history matches what you have been told.
Frequently asked questions
Are UK insurance write-off categories letters or numbers?
They are letters. The current categories are A, B, S and N, replacing the older A, B, C and D system in October 2017. If you see a number such as Cat 1 or Cat 2 in an advert, ask the seller what they mean, because it is not a standard UK category.
What should I do if the seller says Cat N but the record shows Cat S?
Ask for written proof such as the insurer's letter and repair invoices, and do not agree a price until it is resolved. Cat S means structural damage, so it deserves a proper independent inspection. If the seller cannot explain the difference, it is safest to walk away.
Can I check a car's write-off category using just the registration?
Yes, a vehicle history check using the registration can show whether an insurance write-off marker is recorded against the car. It is not a guarantee that nothing has happened, as unclaimed damage will not appear, so combine it with the V5C, VIN checks and a physical inspection.