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Insurance Write-Off Categories: Cat A, B, S and N Explained
Every UK insurance write-off category, what each one means for safety, roadworthiness, finance and resale, and how to check whether the car you are buying carries one.
9 min read·Updated May 2026
In one line
Cat A and Cat B cannot return to the road. Cat S (structural) and Cat N (non-structural) can, after proper repair. The legacy Cat C and Cat D are the pre-October-2017 equivalents of S and N.
What a write-off actually is
A vehicle is "written off" when an insurer decides the cost of repairs after an incident exceeds the car's value, or when the damage is so severe that repair would not be safe at any cost. The insurer settles the claim, takes legal ownership of the car, and assigns it a category recorded against the registration on the Motor Insurance Anti-Fraud and Theft Register (MIAFTR). The marker stays on the car forever, even after the vehicle has been repaired and returned to the road.
The current four-category system (A, B, S, N) was introduced in October 2017. Cars written off before then still carry the older letters A, B, C and D. Cat S replaced Cat C, and Cat N replaced Cat D, with the emphasis shifting from cost-to-repair toward the structural nature of the damage. Both old and new letters remain valid on the MIAFTR register.
Why categories matter to buyers
Three things follow from a write-off marker, all of which affect you as a buyer:
Resale value drops, typically by 20 to 50% depending on the category.
Insurance becomes harder: some insurers refuse to cover written-off cars, others charge a 10 to 20% premium uplift.
Mainstream finance is often refused. HP, PCP and many personal loans will not lend against a Cat S or Cat N vehicle.
All three are recoverable if the price is right and the repair is competent. The danger is paying close to clean-car money for a vehicle with a write-off marker the seller has not disclosed.
Category A – Scrap only
The most serious category. Damage is so severe that the entire vehicle must be crushed and nothing, including individual undamaged parts, can be reused. Cat A vehicles cannot legally return to the road under any circumstance.
Buyer guidance: walk away from any "repaired Cat A" offered for sale. It is illegal to drive and a serious fraud signal.
Category B – Break for parts
The body shell must be crushed, but undamaged mechanical and trim components (engine, gearbox, doors, seats, lights) can be reused in other vehicles. The original Cat B vehicle itself cannot legally return to the road.
Buyer guidance: same as Cat A. A "rebuilt Cat B" for sale is not road-legal.
Category S – Structural damage, repairable
The chassis, subframe, crumple zones or another structural element was damaged. The car can be repaired and returned to the road, but the repair must be carried out by someone qualified, the vehicle must pass an MOT, and DVLA re-registration is required before the V5C is reissued.
Buyer guidance: possible with caution. Expect 20 to 40% off a clean equivalent. Insist on a structural inspection by a body-shop technician before paying.
Category N – Non-structural damage, repairable
Damage was cosmetic or limited to non-structural parts: panels, lights, infotainment, airbags, electrics, interior trim. The frame and crumple zones are sound. Often a Cat N marker results from the cost of replacement parts exceeding the value of an older car, rather than any safety concern.
Buyer guidance: often a fair deal. Expect 10 to 25% off a clean equivalent. Inspect repair quality and confirm the airbags and electrics work as expected.
Category C (legacy) – pre-2017 equivalent of S
Cars written off before October 2017 still carry Cat C if the repair cost exceeded market value but the car was repairable. The threshold and damage criteria differed slightly from Cat S, so treat Cat C as a rough rather than exact equivalent.
Category D (legacy) – pre-2017 equivalent of N
The lighter pre-2017 legacy category. Often light cosmetic damage, sometimes a purely cost-driven write-off on an older or cheap car where any professional repair was uneconomic.
Buying a written-off car: the checklist
Confirm the category first. A paid history check returns the MIAFTR record. Without it you are negotiating blind.
Ask the seller in writing. Dealers must disclose write-off status under the Consumer Rights Act. Private sellers commit fraud if they hide it. Get the answer on paper or by email.
Get an insurance quote up front. Quote both the basic premium and any uplift for the write-off marker. Walk away if no mainstream insurer will cover the car.
Commission an independent inspection. For Cat S, hire a body-shop technician familiar with structural repair. For Cat N, focus on electrics, airbags and infotainment.
Ask for repair documentation. A professional invoice with parts list and labour breakdown is the gold standard. Photos of the repair in progress are even better.
Test drive at length. Straight-line tracking, brake pull, steering feel and unusual noises over rough surfaces are the signs of a poor structural repair.
Insurance and finance implications in detail
Insurance
Failure to disclose a write-off marker to your insurer voids your policy and any future claim. Most insurers ask explicitly during the quote process. A handful will not cover Cat S or Cat N at all; specialist brokers cover the rest, typically at a 10 to 20% premium uplift. Always quote before you buy.
Finance
HP, PCP, conditional sale and many personal loans refuse to lend against a vehicle with a write-off marker. Asset finance, secured loans and dealer in-house finance are sometimes available but at higher rates. Cash buyers have no obstacle.
Resale
The percentage discount is roughly stable across owners. If you buy at 30% off, you will likely sell at a similar discount later. The hit is sharpest in the first three years of ownership; long-term keepers see less impact.
Common scams to watch for
"Unrecorded" damage. The owner paid for repair out of pocket without an insurance claim, so there is no MIAFTR marker. A history check will not flag it, which is where a pre-purchase inspection earns its fee.
Cloned identity. A salvaged write-off is rebuilt using the V5C and registration of a written-off but visually similar undamaged vehicle. Compare the VIN at the windscreen, door pillar and chassis to the V5C.
Cleared marker claims. No-one can remove a MIAFTR marker. Anyone offering to is committing fraud.
Confirm before you buy
Our free check covers DVLA basics. Run a paid Vehicle History Check to confirm a car is not in the MIAFTR write-off register before you commit money.
Cat A and Cat B are hard refusals. Cat S, Cat N, Cat C and Cat D can each be the right buy at the right price with the right inspection and the right insurance quote. Always run a paid history check before any conversation about money, and never accept a seller's word over the MIAFTR record.
