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Write-Off Categories Explained

Cat S & Cat N Check — What the Write-Off Categories Mean

Cat S means repaired structural damage; Cat N means repaired non-structural damage. Both can be perfectly good buys at the right price — or expensive mistakes if the repair was botched. Enter a reg to run the free MOT and mileage signals while you read what each category really means.

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Free MOT & mileage check now. The licensed write-off category (MIAFTR) is a paid record — see below. Last updated: June 2026.

The official Cat A/B/S/N marker lives in the insurance industry's MIAFTR register, not in DVLA or MOT data. This page explains the categories and runs the free signals we hold (MOT history, mileage, V5C reissue date). For the confirmed category, use a licensed HPI-style provider — we'll never pretend to bundle a record we don't license.

The four live write-off categories

Since the 2017 ABI Code of Practice, insurers categorise a written-off vehicle by the severity and type of damage. Cat A and B can never return to the road; Cat S and N can, after repair. Here is what each one actually means for a buyer.

Cat AScrap onlyBack on the road? Never — must be crushed whole

Catastrophic damage. The entire vehicle, including all parts and salvage, is banned from re-entering the road or the parts market. Cat A must be crushed.

Cat BBody shell crushBack on the road? Never — shell must be destroyed

Severe damage. Salvageable parts may be reclaimed and reused, but the body shell itself must be crushed. A Cat B vehicle can never be re-registered for road use.

Cat SStructural — repairableBack on the road? Yes, after professional repair and DVLA re-registration

Structural damage — to the chassis, crumple zones, suspension mounting points or safety cage. Repairable, and can legally return to the road, but must be re-registered with the DVLA and carries the marker permanently.

Cat NNon-structural — repairableBack on the road? Yes, after repair (no re-registration needed)

Non-structural damage — panels, bumpers, lights, electrics, water ingress, trim, glass, or airbags. 'Non-structural' does not mean trivial; deployed airbags and water damage can be expensive and safety-relevant.

Cat S in detail — repaired structural damage

A Category S write-off has suffered structural damage: to the chassis rails, crumple zones, suspension mounting points, or the safety cage that protects occupants in a crash. The insurer decided it was uneconomical for them to repair — usually because the repair cost approached or exceeded the car's value — but the car itself is not beyond saving.

A Cat S car can legally return to the road, but only after a proper structural repair and DVLA re-registration (the car is issued a fresh V5C confirming the structural repair). The marker then stays on the record forever. The critical question for a buyer is repair quality: a jig-aligned, professionally welded structural repair restores the car to full strength; a bonded or bodged repair compromises exactly the crumple zones designed to save your life. For any Cat S purchase, an independent structural inspection is non-negotiable.

Cat N in detail — “non-structural” doesn't mean minor

A Category N write-off has non-structural damage only: panels, bumpers, lights, electrics, water ingress, trim, glass or airbags. No damage to the chassis or safety structure. Because there is no structural work, a Cat N car does not need DVLA re-registration — it keeps its original V5C and simply carries the marker.

Do not read “non-structural” as “cosmetic.” A Cat N write-off can involve deployed airbags (a full airbag and pyrotechnic seatbelt replacement runs into the thousands), flood and water damage (which corrodes wiring looms and ECUs for years afterwards), or extensive electrical faults. The phrase only tells you the safety structure was intact — it says nothing about how expensive or well-executed the repair was. The same evidence checklist applies: full documentation, post-repair inspection, and a price that reflects the category.

Is it worth buying a Cat S or Cat N car?

There is no universal yes or no — it depends on the discount, the evidence, and your plans. Weigh these honestly before you commit — or read our full honest guide to buying a Cat S or Cat N car for the complete decision rule.

When it can make sense

  • The price is genuinely 15–40% below a clean equivalent.
  • You have full repair documentation and ideally photos of the damage.
  • An independent inspection confirms the repair quality.
  • You plan to keep the car for years, not flip it.
  • Your insurer quotes a workable premium on the declared category.

When to walk away

  • No proof of who recorded it or how it was repaired.
  • The seller is vague about the damage or won't allow an inspection.
  • The discount is small — you carry the resale and insurance hit for little saving.
  • It's sold as “unrecorded” but a check shows a category (a common cloning tell).
  • A Cat S with no DVLA re-registration record.

Insurance & resale impact at a glance

Expect comprehensive premiums roughly 10–25% higher than a clean car (and occasional refusals), and a resale value that stays 15–40% below market for the life of the car — Cat S typically takes the larger hit because of the structural history. You must declare the category on every insurance application and to any future buyer; failing to do so can void a claim or unwind a sale.

What the free MOT history can hint at

A history check won't confirm a write-off category — that needs the paid MIAFTR record — but the free DVSA MOT data is a genuine cross-check. Look for:

  • A gap in the MOT test history around the time of the damage.
  • A cluster of post-repair advisories appearing after that gap.
  • Structural or corrosion advisories on a car supposedly repaired to standard — run the MOT failure history to spot the pattern.
  • Mileage that doesn't add up — check the mileage history for rollbacks, since clocking and undisclosed write-offs often travel together.

Cat S & Cat N FAQ

What is the difference between Cat S and Cat N?
Cat S means the vehicle suffered structural damage — to the chassis rails, crumple zones, suspension mounting points or safety cage — which has since been repaired. Cat N means non-structural damage only: panels, electrics, water ingress, trim, glass or airbags, with no damage to the safety structure. Both categories permit a return to the UK road after repair, but a Cat S car must be re-registered with the DVLA and will show the marker on every future history check. Cat N does not require re-registration. Both were introduced by the 2017 ABI Code of Practice, replacing the older Cat C and Cat D.
Is it worth buying a Cat S or Cat N car?
It can be, if the discount reflects the risk and the repair is sound. A well-repaired Cat N or Cat S car typically sells 15–40% below an equivalent clean-history example, which is a genuine saving if you plan to keep it. The risks are: lower and slower resale, higher or occasionally refused insurance, and the chance of a poor-quality repair. Buy one only with full repair documentation, an independent post-repair inspection (especially for Cat S structural work), a price that clearly reflects the category, and realistic resale expectations. Without proof of who recorded it and how it was repaired, walk away.
Can you insure a Cat S or Cat N car?
Yes in most cases. Comprehensive cover is available from many mainstream insurers for both categories, but premiums are typically 10–25% higher than for an equivalent clean car, and some insurers — particularly for younger drivers or higher-value vehicles — will decline. Specialist insurers actively quote on write-off categories. You must always declare the category when applying: undisclosed write-off history is a standard ground for voiding a policy after a claim.
Is a Cat S or Cat N car safe to drive?
It depends entirely on the repair quality. A Cat S car with a professional, jig-aligned structural repair and completed DVLA re-registration is mechanically equivalent to a clean car of the same model and age. A botched repair — bonded sections instead of welded, missing crumple zones, mismatched alignment — is materially less safe in a future collision. For Cat S in particular, an independent pre-purchase inspection (£150–£250 at the AA or RAC) is straightforward insurance before you buy.
How can I check if a car is Cat S or Cat N?
There is no fully free check that returns the actual MIAFTR write-off record. The official Cat A/B/S/N marker is held in the insurance industry's MIAFTR register, not in DVLA or MOT data, so a paid HPI-style check (Total Car Check, RAC or HPI) is the only consumer route to the confirmed category. The free signals you can check — DVLA tax and MOT status, V5C verification, gaps in the MOT history, and physical evidence of repair — catch many write-offs but do not confirm the category. MOT Checkup's free tier covers the MOT layer; for the licensed write-off layer we point you to a paid provider rather than pretend to bundle data we don't license.
What's the relationship between Cat S/N and the old Cat C/D?
Cat C and Cat D were the legacy ABI categories used until October 2017. Cat C was the previous structural / uneconomical-to-repair category, broadly equivalent to today's Cat S. Cat D was the previous non-structural category, broadly equivalent to today's Cat N. A car written off before October 2017 will still show the legacy Cat C or Cat D marker on a history check rather than the new letters.
Does the write-off category ever expire?
No. The Cat S or Cat N marker stays on the vehicle's record permanently. It does not fade, reset or expire, and it shows on every future history check for the life of the car. That permanence is the main reason write-off-category cars sit well below market value throughout their resale life — and why undisclosed write-offs are a recurring used-car fraud.
Can MOT history reveal a repaired write-off?
Indirectly. The MOT record won't tell you a car is a write-off, but it can show supporting signals: a gap in the test history around the time of the damage, a cluster of post-repair advisories, or corrosion and structural advisories on a car that was supposedly repaired to standard. Combined with a physical inspection for overspray, panel-gap mismatches and replaced bolts, the free MOT history is a useful cross-check alongside a paid category check.

More checks before you buy

Run all of these on any UK car before you pay a deposit — every one is free to start.

Full Car Check

MOT, mileage, tax and spec by reg — the free starting point.

MOT History Check

Every test, advisory and failure on the DVSA record — free.

Mileage / Clocking Check

Spots odometer rollbacks and implausible jumps across MOTs.

MOT Failure History

Pass-rate and recurring-failure patterns from MOT history.

Outstanding Finance

Why unpaid finance can cost you the car — and how to verify.

Stolen Car Check

The warning signs of a stolen vehicle before you pay a deposit.

Write-Off Check

Cat A/B/S/N explained and what a write-off means for buyers.

HPI Check Alternative

What each check covers and costs — an honest price comparison.

Car Tax Check

Tax status, due date and SORN by registration — free.

Used Car Buying Checklist

The full step-by-step checklist before you buy a used car.

Buying a Cat S / Cat N Car

Is a write-off worth it? The honest costs, risks and decision rule.

Check Finance Before Buying

Why there's no free finance check — and how to verify before you pay.

What Does HPI Clear Mean?

Why an 'HPI clear' result does NOT mean accident-free.

How to Spot a Clocked Car

The tell-tale signs of mileage fraud before you buy.

What Is a Cat S Car?

Category S write-off meaning — structural damage, explained.

What Is a Cat N Car?

Category N write-off meaning — and why 'non-structural' isn't 'minor'.

Run the free checks on a car you're considering

Enter any UK registration for the free MOT and mileage signals, then add a paid category check before you buy a write-off.

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