What is a write-off?
A write-off is a vehicle that an insurance company has declared either too dangerous or too expensive to repair after a claim. The decision is made on commercial grounds: the insurer compares the cost of repair against the vehicle's pre-incident market value, and writes the car off when the repair cost exceeds a threshold the insurer is willing to pay.
The threshold isn't fixed in law, but in practice most UK insurers will write a car off when the estimated repair cost exceeds 50-60% of the pre-accident market value. For older or lower-value cars the threshold is often crossed by relatively minor damage — a fender-bender on a £2,000 hatchback can easily total it economically without doing any structural harm.
Once the insurer makes the write-off decision, they report it to the Motor Insurance Anti-Fraud and Theft Register (MIAFTR), which is run by the Association of British Insurers (ABI). That marker stays attached to the vehicle's history file permanently. Even if the car is rebuilt, sold to a third party and changes hands a dozen times, the marker remains visible on every future history check.
How the data reaches a write-off check
Three databases feed UK write-off checks:
- MIAFTR (Motor Insurance Anti-Fraud and Theft Register) — the central insurance write-off database, managed by the ABI on behalf of UK insurers
- MIB (Motor Insurers' Bureau) — handles uninsured driver and untraced driver cases, contributes some overlapping data
- DVLA — vehicle registration status, including notification flags where an insurer has informed DVLA of a total loss
Experian aggregates and normalises data from all three sources. When you run our write-off check, the lookup runs against the combined dataset in real time and returns the category (if any), the date the marker was added, and where available the name of the insurer that filed the claim.
Every UK write-off category explained
UK write-off categories were updated by the ABI in October 2017. The current categories are A, B, S and N. Pre-2017 cars may still carry the legacy categories C and D, which never get reclassified. Every category is summarised below.
Cat ACurrentNot road-legal
Catastrophic damage where the entire vehicle must be crushed. No parts can be salvaged or reused on other cars. Cat A vehicles cannot legally return to the road as complete vehicles, and the parts cannot legally re-enter the supply chain. If a check returns Cat A on a car being offered for sale, walk away immediately and consider reporting the listing.
- Damage:
- Severe — scrap only
- Insurance:
- Cannot be insured for road use.
- Finance availability:
- No finance available.
Cat BCurrentNot road-legal
The body shell of the vehicle must be destroyed, but salvageable parts (engine, gearbox, doors, wheels) can be reused on other vehicles. The Cat B vehicle itself cannot return to the road as a complete car. As with Cat A, a Cat B marker on a car offered for road use is a serious red flag.
- Damage:
- Severe — body shell crush
- Insurance:
- Cannot be insured for road use.
- Finance availability:
- No finance available.
Cat SCurrentRoad-legal if repaired
Structural damage to the chassis or load-bearing components (crumple zones, A/B/C-pillars, sub-frame). The insurer decided repair was uneconomical but the damage can be repaired by a competent body shop. Cat S cars must be re-registered with the DVLA after repair using a V62 application. The marker stays attached to the vehicle history permanently. Replaced Cat C in October 2017.
- Damage:
- Structural — repairable
- Insurance:
- Premiums typically 20-40% higher than equivalent unmarked cars. Some insurers refuse to quote.
- Finance availability:
- Restricted — most mainstream lenders refuse. Specialist lenders available at higher APRs.
Cat NCurrentRoad-legal if repaired
Damage to non-structural components — typically electrical systems, infotainment, trim, glass, lights or cosmetic body panels. The damage exceeded the insurer's economic repair threshold but the car can be repaired and returned to the road. Cat N does not require DVLA re-registration. The marker stays on the history file. Replaced Cat D in October 2017.
- Damage:
- Non-structural — repairable
- Insurance:
- Premiums typically 10-25% higher. Most insurers will quote.
- Finance availability:
- Most mainstream lenders will fund. APRs broadly comparable to unmarked equivalents.
Cat CLegacyRoad-legal if repaired
The legacy category used before the October 2017 ABI reclassification. Functionally equivalent to today's Cat S — structural damage that was uneconomical for the insurer to repair but could be repaired by a body shop. You'll still see Cat C on older cars (typically 2017 model year and earlier); the marker is never reclassified to Cat S.
- Damage:
- Structural — repairable (pre-2017)
- Insurance:
- Same treatment as Cat S — premiums 20-40% higher, some insurers refuse.
- Finance availability:
- Same restrictions as Cat S.
Cat DLegacyRoad-legal if repaired
The legacy category used before October 2017. Functionally equivalent to today's Cat N — lower-cost, non-structural damage that was uneconomical to repair through an insurer. Common on older used cars. Treat the same way as Cat N: most are perfectly safe if competently repaired.
- Damage:
- Non-structural — repairable (pre-2017)
- Insurance:
- Same treatment as Cat N — typically 10-25% premium uplift.
- Finance availability:
- Similar availability to Cat N.
Can you buy a written-off car?
Cat S, Cat N, Cat C and Cat D cars are legal to buy and drive once they have been repaired to a roadworthy standard. Many repaired write-offs return to the road with no issues at all. In particular, Cat N and Cat D cars (non-structural damage) can often be excellent value — buyers get a car at 25-30% below market price for damage that has been fully repaired and poses no ongoing safety risk.
Cat S and Cat C cars (structural damage) carry more risk because the integrity of the chassis or crumple zones may have been compromised. A properly repaired Cat S car is safe; a poorly repaired Cat S car can fail in a future collision in ways that an unmarked car wouldn't. Always demand documentation of the repair and ideally an independent mechanical inspection before buying any structural write-off.
Cat A and Cat B cars cannot legally return to the road as complete vehicles. If you see a Cat A or Cat B marker on a car being offered for sale, treat it as a major red flag: either the seller doesn't understand the rules (in which case they may not understand other important things either), or the car has been illegally ringed (parts of a destroyed car welded onto another shell, often with stolen identifiers).
Selling a written-off car
You can legally sell a Cat S, N, C or D car. There's no strict UK law requiring private sellers to disclose a write-off marker proactively, but failing to disclose can expose you to a misrepresentation claim if the buyer can prove you knew. In practice, any half-competent buyer will run a check before completing — so the question isn't whether they'll find out, but whether you tell them upfront.
Best practice is to disclose the marker in the listing, set the price accordingly, and have repair documentation available for buyers to review. Cars sold with full transparency about a write-off typically achieve the higher end of the discounted range; cars where the marker is discovered partway through the sale lose more on price and often fall through entirely.
Insurance implications of buying a write-off
You are legally required to declare a Cat A, B, S, N, C or D marker on every insurance quote. Failure to disclose can result in the policy being voided retrospectively — meaning you'd be uninsured at the moment of any future claim, with potentially severe legal and financial consequences.
Real-world insurance treatment varies by category:
- Cat N and Cat D are usually quotable from mainstream insurers, often with a modest premium uplift (10-25%)
- Cat S and Cat C are quotable from a smaller pool of insurers with significant uplifts (typically 20-40%, occasionally higher). Some mainstream insurers refuse outright
- Cat A and Cat B cannot be insured for road use because they cannot legally be on the road
Always get an insurance quote in writing before committing to a marked car. If your usual insurer refuses, specialist brokers like Adrian Flux and ChoiceQuote handle this market.
Finance availability for written-off cars
Mainstream PCP and HP lenders generally won't fund Cat S or Cat C cars. They view the residual value as too unpredictable. Cat N and Cat D cars have wider availability but still face some restrictions, particularly for high-value vehicles where the lender's margin on the residual matters most.
Specialist write-off lenders (typically branded as "adverse" or "non-standard" lenders) do offer finance on Cat S and C cars, but APRs are usually several percentage points higher than mainstream rates. If you need finance, get an indicative quote before committing to the car.
DVLA re-registration after a Cat S repair
A car written off as Cat S must be re-registered with the DVLA before it returns to the road. The owner submits a V62 application along with the repair documentation. The DVLA issues a new V5C and the original registration is reused. The Cat S marker remains visible on the vehicle history file.
For higher-value structural repairs, the DVLA may require the vehicle to pass an Individual Vehicle Approval (IVA) test before re-registration. The IVA confirms the rebuilt car meets UK construction and use standards. Not every Cat S car needs an IVA — the requirement depends on the extent of the repair and the components replaced.
Cat N cars don't need re-registration; the original V5C remains valid.
How to inspect a repaired write-off
If you're seriously considering a repaired Cat S or Cat C car, an independent mechanical inspection is essential. Expect to pay £150-£300 for a full inspection from an independent specialist. The inspector should check specifically for:
- Panel gaps and alignment — uneven gaps usually indicate a poorly aligned shell after structural repair
- Weld quality on repaired sections, especially A/B/C pillars and sub-frame mounts
- Paint thickness consistency across panels (a paint depth gauge picks up filler quickly)
- Wheel alignment and four-wheel tracking — a chassis that's slightly out of true won't hold alignment
- Airbag system status — deployed airbags should have been replaced with OEM parts
- Crash structure documentation — has the repairer provided photos of the repair stages?
For a car bought from a dealer rather than privately, the Consumer Rights Act 2015 gives you the right to reject the car if the inspector finds material defects — but you have to assert that right quickly (within 30 days for an automatic short-term right to reject).
How to run a write-off check
- Enter the UK registration of the car you want to check.
- Pay £14.99 securely via Stripe.
- Receive your full report in under a minute, covering write-off, finance, stolen, mileage and MOT data.
Frequently asked questions
Can you legally drive a Cat S or Cat N car?
Yes, once repaired to a roadworthy standard. Cat S requires DVLA re-registration after repair; Cat N does not. Cat A and Cat B cannot legally return to the road.
How much does a write-off devalue a car?
Cat S/C typically 30-50% off; Cat N/D typically 20-30% off. The exact discount depends on repair quality, documentation, vehicle age and value.
What is the difference between Cat C and Cat S?
Cat C is the pre-October 2017 label; Cat S is the current equivalent. Both indicate repairable structural damage. Older cars keep their original Cat C marker.
Will every write-off show up on a check?
Only if the insurer reported it to MIAFTR. Damage repaired without an insurance claim won't show. Always inspect the car in person too — see our used-car buying checklist.
Do I have to declare a write-off when getting insurance?
Yes — non-disclosure can void the policy. Always declare, get the quote, then decide whether to proceed.
Can you get finance on a Cat S car?
Most mainstream lenders refuse. Specialist lenders fund Cat S/C cars at higher APRs. Cat N/D have wider availability.
