What cat is my car? usually means one of two things. Most often it is a question about insurance write-off categories, where "cat" is short for category and the letters A, B, S and N show how an insurer classed a damaged car. Less often, people mean the catalytic converter, the "cat" in the exhaust. Both are covered here, starting with the write-off categories.
Part of Used Car History. Start with the main guide: HPI Clear: What a Clear Vehicle History Means
Updated October 2026 · Independent information, not legal advice
The free MOT lookup cannot tell you a car's write-off category, because that is held in insurance and vehicle history records rather than MOT data. A vehicle history check can. Knowing the letter matters, since it affects safety, insurance, resale value and whether the car should be on the road at all.
What "cat" Means In A Used Car Advert
In an advert, "Cat S" or "Cat N" is the category letter for a write-off. A "cat" in a repair or theft story is the catalytic converter.
Write-off meaning
An insurance write-off happens when an insurer decides repair costs are not worth it compared with the car's value, or the car is too damaged to repair safely. The category tells buyers how to treat it afterwards.
Catalytic converter meaning
A catalytic converter is an exhaust part that reduces harmful gases. It matters for MOT emissions tests and is a common theft target.
The Current Write-Off Categories
Since 2017 four categories are used in Great Britain. These are Category A, Category B, Category S and Category N.
- Category A: scrap only, never to return to the road
- Category B: break only, the body shell is crushed but parts can be reused
- Category S: repairable but the car had structural damage
- Category N: repairable, damage was non-structural
| Category | General meaning | Usual outcome |
|---|---|---|
| Category A | Scrap only, not for road use | Crushed; parts may be salvaged |
| Category B | Body shell not for road use | Parts may be reused |
| Category S | Structurally damaged, repairable | Repair evidence matters |
| Category N | Non-structural damage | Repair quality still matters |
Why the lettering changed
The older lettering, including former Category D, was replaced so that the labels describe the damage, not just the cost. Check Category N car meaning for the detail of S and N.
Category A Explained
A Category A car should be crushed. Nothing from it should be reused, and it must never be put back on the road.
Why you might still see the term
A genuine car at this level should not be advertised for road use. An advert claiming Cat A for a driveable car is a red flag.
Category B Explained
A Category B car cannot be repaired for the road, but certain parts can be salvaged. The body shell must be crushed.
What happens to the parts
Undamaged components may be sold on. The shell itself should not be rebuilt into a road car.
Category S Explained
Category S means the car's structure, such as the chassis or frame, was damaged but it can be repaired. Repair must be carried out to a proper standard before road use.
Why the structure matters
Structure absorbs crash energy. A poor repair may behave badly in a future collision. Independent inspection is wise.
Buying a Cat S
If you consider one, ask for repair evidence and photographs. The price should reflect the history, and some insurers may decline or charge more.
Category N Explained
Category N means the car was damaged, but not structurally. Examples can include electrical, cosmetic or mechanical damage that cost too much to fix in the insurer's view.
Do not assume it is minor
Non-structural damage can still be serious. Get a full inspection; see vehicle inspection check for the steps.
What About The Old Category D?
Before the new system, cars were labelled under different letters, including Category C and former Category D. You may still see these in older records and adverts.
How to read them
Treat old categories as a prompt to seek details about what was damaged and how it was repaired. Read Category D car meaning for the older scheme.
How To Find Out Your Car's Category
You cannot usually tell from the registration alone, so use records and checks.
- Check the V5C for any marker or note.
- Ask the seller directly and request repair documents.
- Run a vehicle history check that includes write-off records.
- Compare it with the free MOT history for odd gaps.
Where the data sits
When a car is declared a total loss, the insurer normally records the category and the salvage is sold on, often through auction. A later buyer may repair it and return it to the road, which is when the history matters most to the next owner.
Insurers report write-offs to the industry database known as MIAFTR, and history providers draw from it. Coverage and timing vary.
Check If My Car Has Been In An Accident
To check if my car has been in an accident, there is no single official accident register. Accident damage that was repaired privately may not appear anywhere.
Clues to look for
- Uneven panel gaps and mismatched paint
- Repeated advisories for the same area in the MOT history
- Repair invoices that mention body or chassis work
- A marker in a paid history report
Ask the seller
Ask plainly if the car has been in an accident and for any documents from the garage. Our guide to check if a car has been written off covers the steps.
Checking The MOT History For Hints
Although it cannot give a category, MOT history helps. A long gap after an accident and then a return to testing can be a clue.
What the free lookup shows
Enter the plate into the free MOT history checker to see past failures such as corrosion near structural points, and advisories about repaired areas.
Insurance And Write-Off Cars
Insurers may treat a previously written-off car differently. Category S and Category N cars can be harder or costlier to cover.
What to tell your insurer
Declare the car's history when asked. Failing to disclose may affect a claim. Compare the position on is my car insured after buying.
Selling A Car That Was Written Off
If you sell one, you must be honest about its category. Misdescribing a car may breach consumer law and can lead to disputes.
Keep repair evidence
Invoices, photographs and any independent inspection help the next owner and support your asking price.
Mistakes Buyers Make About Categories
Some common misunderstandings cause trouble.
- Believing Cat N is always cosmetic
- Assuming a clean MOT means no crash history
- Trusting a seller's verbal description only
- Thinking the V5C always shows the category
Why one check is not enough
A history report can miss very recent write-offs, cars repaired abroad and damage never claimed through insurance. A seller's own account can be mistaken or incomplete. Cross-checking the V5C, MOT history, invoices and your own inspection gives a far more reliable picture.
Use several sources. No database is perfect and records can lag.
Now The Other Cat: The Catalytic Converter
The catalytic converter sits in the exhaust and converts harmful gases into less harmful ones. Petrol and diesel cars built in recent decades nearly all have one, and some also have a diesel particulate filter.
Why it matters at MOT
The MOT tests exhaust emissions, and a missing or damaged converter can cause a fail. Details on the MOT are in MOT check.
Catalytic Converter Theft
Converters contain precious metals, so they attract thieves. Signs include a sudden loud roar from the exhaust and a warning light.
What to do
- Report the theft to the police and your insurer
- Do not keep driving if unsafe or illegal for emissions reasons
- Arrange a proper replacement from a reputable garage
- Consider security marking or parking in well-lit spaces
Selling Or Buying A Car Without Its Cat
A car with a missing converter may fail its MOT and may not be legal for road use. Do not buy a vehicle in this state without understanding the repair.
Used converters
The replacement must suit the engine and emissions standard of the car. A part that fits physically may still cause a warning light or an emissions fail, so ask for the part details in writing.
Fitting a cheap or non-approved converter may not meet requirements. Ask a garage what is suitable for the model.
How To Tell Whether Your Car Has A Catalytic Converter
Look at the exhaust system under the car or check the vehicle's specification. Most petrol cars made since the early 1990s have one.
Using the lookup
The free lookup can show fuel type, engine size and Euro status where recorded, which gives a hint about emissions equipment. Check CO2 emissions checker for more on emissions data.
Imports And Unusual Vehicles
An imported vehicle may have had its category recorded abroad, and records may not cross borders easily. See car import check for how to spot imports.
Motorbikes
Bikes also get write-off categories. The same principles apply; see motorbike HPI check.
Questions To Ask Before Buying Any Cat Car
- Which category was it and when?
- What was damaged?
- Who did the repair, and is there paperwork?
- Has an independent engineer inspected it?
- Has it passed an MOT since repair?
Walk away when answers are vague
A seller who avoids details may be hiding something.
When The Record Looks Wrong
If you believe the category on a record is wrong, contact the history provider or the insurer who reported it. Keep documents.
Official routes
The DVLA handles registration records. For vehicle write-off disputes, start with the insurer and seek advice from consumer organisations.
Safety Checks On A Repaired Write-Off
A repaired write-off can be perfectly sound, but the quality of the repair is what counts. Airbags, crumple zones and seat belt mountings all rely on the structure being restored properly.
What an engineer can check
An independent engineer or specialist can look at weld quality, panel alignment, suspension geometry and whether airbags and sensors have been replaced with correct parts.
- Ask whether genuine or approved parts were used
- Ask for before and after photographs
- Check the warning lights for airbag or stability faults
- Look for signs of the car pulling to one side on a test drive
Why the MOT is not enough
An MOT checks roadworthiness on the day. It is not a judgement on repair quality or how the car would perform in a crash.
Resale later
Expect the category to follow the car for life. Future buyers may also ask about it, and it may affect value.
Quick Reference: Cat Terms
Short definitions to keep handy.
- Cat A: scrap
- Cat B: break
- Cat S: structural repairable
- Cat N: non-structural repairable
- Cat: catalytic converter
Summary
In short, the letter tells you how badly the car was damaged and whether repair was allowed, while the catalytic converter is an emissions part.
Use a history check, inspect the car and ask for proof. Confirm current rules on GOV.UK and with the DVLA.
Frequently Asked Questions
What cat is my car?
If you mean a write-off category, you will find it in insurance and history records, not in the MOT data. The letters are A, B, S and N under the current scheme. If you mean the catalytic converter, it is a part of the exhaust. A paid history check, the V5C and the seller's paperwork are the usual sources.
What does Cat S mean on a car?
Category S means the vehicle was written off because of structural damage but could be repaired for the road. It needs a proper repair by a competent person, and independent inspection is sensible before buying. Insurers may treat it differently. The exact rules are on GOV.UK.
What does Cat N mean?
Category N means non-structural damage, such as electrical, mechanical or cosmetic problems, that an insurer judged uneconomic to repair. The car can be repaired and returned to the road. Do not assume it is minor, and ask for evidence of the repair before you commit.
Can Category A or B cars be driven?
No. Category A is scrap only, and Category B is break only, so the body shell should be crushed and only certain parts reused. A car sold as driveable under either label would be a serious warning sign, and you should walk away and consider telling Trading Standards.
How do I check if my car has been in an accident?
There is no single register of accidents. Start with a paid history check that includes write-off data, then compare MOT history, the V5C and repair invoices. Inspect the bodywork for mismatched paint and uneven gaps, and ask the seller directly. Minor repaired damage may never have been recorded.
Does the MOT history show the write-off category?
No. The MOT history lists test results, advisories, failures and mileage. It may hint at repaired areas through advisories or gaps, but the category comes from insurance records. A history check, not the free lookup, is the place to look.
Is a catalytic converter the same as a cat?
In motoring slang, yes. A "cat" often refers to the catalytic converter in the exhaust, which reduces harmful emissions. Online, the same word is also used as shorthand for write-off category, so context matters. This is why the question is ambiguous when typed into a search engine.
Why are catalytic converters stolen?
They contain precious metals, which gives them scrap value. Thieves can remove one quickly from under a car. If yours is stolen, report it to the police and your insurer, and get a proper replacement before relying on the car for road use or an MOT.
Will a missing catalytic converter fail an MOT?
It very often will, because the test includes emissions and checks for required exhaust components. A missing or damaged converter can also make the car louder and illegal for road use in many cases. Ask a garage what applies to your model and check the official MOT guidance.
Can I insure a Cat S or Cat N car?
Usually yes, but some insurers decline or price differently, so be honest about the history when asked. Non-disclosure could affect a claim. Compare quotes and be ready to provide repair evidence.
Are old Category D cars the same as N?
Not exactly. The former scheme used different letters, and former Category D generally covered repairable cars with less serious damage, but the new letters are not a simple one-to-one match. Treat old labels as a reason to ask more questions.
Can a seller hide a write-off category?
A dishonest seller might try, which is why you should never rely on a verbal answer. Run your own history check using the registration and VIN you see on the car, compare the V5C and MOT history, and inspect the bodywork. If details do not add up, walk away or seek independent advice before paying.
Where does write-off information actually come from?
Insurers report write-offs to industry databases, and the Police National Computer holds details of a stolen vehicle. A full history check may also show outstanding finance, the number of previous keepers and whether the car was a scrapped vehicle. Free MOT lookups do not show these, nor service history. Use the V5C logbook to compare details and judge vehicle provenance.
Official Sources
Rules, fees and deadlines change. Confirm anything that affects your money or legal position with the official service.