Car Insurance Write-Off Categories Explained: Cat A, B, S & N
What Is an Insurance Write-Off?
When a vehicle is damaged – whether through an accident, flood, fire, or theft recovery – the owner's insurance company assesses the cost of repairs against the vehicle's current market value. If the repair cost exceeds the value of the vehicle (or a significant proportion of it), the insurer declares the vehicle a “write-off” or “total loss”. At that point, the insurer pays out the vehicle's pre-accident value to the policyholder and takes ownership of the salvage.
It is important to understand that a write-off does not necessarily mean the car is undriveable or beyond repair. In many cases, particularly with less severe categories, the vehicle can be repaired and returned to the road. The write-off designation simply means that, from the insurer's perspective, it was not economically worthwhile for them to fund the repairs. This distinction matters enormously if you are considering buying a previously written-off vehicle.
The Four Write-Off Categories
Insurance write-offs in the UK are classified into four categories, each reflecting the severity of damage and whether the vehicle can legally return to the road.
Category A (Scrap)
Category A is the most severe classification. A vehicle given a Cat A marker must be crushed entirely – it cannot be repaired, and no parts can be salvaged or sold. This category is typically reserved for vehicles that have suffered catastrophic damage, such as being completely destroyed by fire, severely submerged in water, or involved in an impact so extreme that every component is compromised. Cat A vehicles are effectively removed from existence and will never appear on the road again.
Category B (Break)
Category B vehicles have also sustained severe damage, but unlike Cat A, individual parts may be salvaged and sold. However, the body shell itself must be crushed and the vehicle can never return to the road as a complete car. You might find components from a Cat B vehicle being sold through breakers' yards, but the vehicle as a whole cannot be rebuilt or re-registered for road use.
Category S (Structural)
Category S indicates that the vehicle has sustained structural damage. This means the chassis, frame, crumple zones, or other load-bearing components have been affected. Despite this, Cat S vehicles can be professionally repaired and legally returned to the road. Before the October 2017 reclassification, this category was known as Cat C. If you are buying a Cat S vehicle, it is strongly recommended that you have the structural repairs independently inspected by a qualified engineer to ensure they have been completed to a safe standard.
Category N (Non-Structural)
Category N covers vehicles with non-structural damage – this includes cosmetic damage (dents, scratches, bumper damage), mechanical faults (engine or gearbox issues), or electrical problems. The vehicle's structural integrity has not been compromised. Cat N vehicles can be repaired and returned to the road, and there is no mandatory inspection requirement before doing so. Previously known as Cat D, this is the most common write-off category and many Cat N cars have suffered only minor cosmetic damage.
Old vs New Categories
In October 2017, the Association of British Insurers (ABI) overhauled the write-off classification system. The old categories – A, B, C, and D – were replaced with A, B, S, and N. Categories A and B remained essentially the same, but the lower two categories were fundamentally redesigned.
| Old System | New System | Key Difference |
|---|---|---|
| Category A (Scrap) | Category A (Scrap) | Unchanged – vehicle must be crushed entirely |
| Category B (Break) | Category B (Break) | Unchanged – shell crushed, parts can be salvaged |
| Category C | Category S (Structural) | Now based on damage location, not repair cost vs value |
| Category D | Category N (Non-Structural) | Now based on damage location, not repair cost vs value |
The fundamental change is in how the lower categories are determined. Under the old system, Cat C and Cat D were based primarily on the relationship between repair cost and vehicle value. Under the new system, Cat S and Cat N are determined by where the damage is located – structural versus non-structural – regardless of cost. This gives buyers much clearer information about the nature of the damage a vehicle has sustained.
Should You Buy a Write-Off?
Buying a previously written-off vehicle can represent genuine value for money, but it comes with risks that you need to weigh carefully. The answer depends heavily on which category the vehicle falls into and the quality of any repairs that have been carried out.
| Factor | Category S | Category N |
|---|---|---|
| Typical price reduction | 30–40% below market value | 20–30% below market value |
| Nature of damage | Structural (chassis, frame, crumple zones) | Non-structural (cosmetic, mechanical, electrical) |
| Repair complexity | High – requires specialist bodywork | Low to moderate – often straightforward |
| Inspection requirement | No legal requirement, but strongly recommended | No legal requirement |
| Insurance availability | Some insurers refuse; premiums often higher | Most insurers will cover; premiums may increase slightly |
| Resale value | Permanently reduced; harder to sell | Reduced but less stigma than Cat S |
Many Cat N vehicles have suffered only minor cosmetic damage – a dented bumper, scratched panels, or a cracked headlight – and can be excellent bargains once repaired. Cat S vehicles require more caution: while they can be perfectly safe when repaired by qualified professionals, poor-quality structural repairs can compromise the vehicle's safety in a future collision.
Warning: Never buy a Cat S vehicle without having the structural repairs independently inspected. Poorly repaired structural damage can compromise crumple zones and put occupants at serious risk in an accident.
How to Check If a Car Is a Write-Off
Write-off status is not visible from a standard free vehicle check. To find out whether a car has been previously written off, you need a premium vehicle history report that searches insurance industry databases, specifically the Motor Insurance Anti-Fraud and Theft Register (MIAFTR).
CheckMyReg premium reports include a write-off check as part of a comprehensive vehicle history search. This check will reveal whether the vehicle has ever been declared a total loss by an insurance company, along with the write-off category assigned. The marker is permanent – once a vehicle is recorded as a write-off, that record stays on its history forever, even after full repair.
Important: Always run a write-off check before buying any used car, especially if the asking price seems unexpectedly low. A vehicle that appears to be a bargain may have a hidden write-off history that explains the reduced price.
What Does a Write-Off Mean for Insurance?
A write-off marker has practical implications for insurance, whether you already own the vehicle or are considering buying one.
If you own a write-off
You are legally required to disclose the write-off history to your insurer when taking out or renewing a policy. Failure to do so could invalidate your cover. Insurance premiums for previously written-off vehicles are typically higher, reflecting the increased risk associated with repaired damage. Some insurers will not cover Cat S vehicles at all, so you may need to shop around or use a specialist provider.
If your car is written off by your insurer
When your insurer declares your vehicle a total loss, they will offer you a settlement based on the vehicle's pre-accident market value. You have several options:
- Accept the payout – take the offered amount and the insurer keeps the salvage. This is the simplest option.
- Negotiate the valuation – if you believe the insurer's valuation is too low, you can challenge it by providing evidence of similar vehicles selling for more. Use listings from major car sales websites to support your case.
- Buy back the salvage – you can choose to keep the vehicle by buying it back from the insurer. The insurer will deduct the salvage value from your payout. You then own the vehicle but it retains its write-off marker permanently, and you are responsible for arranging and funding any repairs yourself.
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Check a vehicle nowFrequently Asked Questions
Can I still drive a Cat S or Cat N car?
Yes. Both Category S and Category N vehicles can be legally repaired and returned to the road. However, Category S vehicles should have structural repairs professionally inspected before use.
Does a write-off marker affect the car's value?
Yes. A write-off marker permanently reduces a vehicle's resale value, typically by 20-40% compared to an equivalent non-written-off vehicle. This applies even if the car has been fully repaired.
What is the difference between Cat C and Cat S?
Cat C was replaced by Cat S in October 2017. The old system was based on repair cost vs value. The new Cat S specifically means structural damage, regardless of cost. Cat D was replaced by Cat N (non-structural damage).