If you've bought a used car or had an insurance claim, you've probably heard the terms "Cat N" and "Cat S" thrown around. But what do they actually mean? And more importantly, how do they affect your car's value and your ability to sell it?
In this comprehensive guide, we'll break down everything you need to know about insurance write-off categories in the UK, including the old Cat C and Cat D system, and help you understand exactly what these markers mean for your vehicle.
Quick Summary
Cat N (Non-Structural)
- No structural/chassis damage
- Cosmetic or mechanical damage only
- Generally safer to buy when repaired
- Retains more resale value
Cat S (Structural)
- Structural frame has been damaged
- Requires professional structural repair
- More risk if repairs are substandard
- Lower resale value
What Are Insurance Write-Off Categories?
When a car is involved in an accident, theft, fire, or flood, the insurance company assesses whether it's economically viable to repair. If the repair cost exceeds a certain percentage of the car's value (typically 50-70%), it's declared a "write-off" or "total loss."
But here's the important part: a write-off doesn't mean the car is worthless or unrepairable. It simply means the insurer has decided it's not worththem fixing it. Many write-offs are repaired and returned to the road.
To help buyers understand what they're getting, the Association of British Insurers (ABI) introduced a category system in 2017. This replaced the old Cat A, B, C, D system with a clearer structure: Cat A, Cat B, Cat S, and Cat N.
The Four Write-Off Categories Explained
Category A - Scrap Only
The vehicle must be crushed. No parts can be salvaged, not even for spares. This is reserved for vehicles that are so badly damaged or dangerous that nothing is safe to reuse. Cat A write-offs cannot legally return to the road.
Examples: Fire-damaged vehicles, severe chemical contamination, cars involved in serious accidents.
Category B - Body Shell Must Be Crushed
The body shell must be destroyed, but parts can be salvaged for reuse. The car itself can never return to the road, but the engine, gearbox, electronics, and other components can be sold as spares.
Examples: Severe structural damage where the shell is unsafe, but mechanical parts are unaffected.
Category S - Structural Damage (Repairable)
The car has sustained structural damage - meaning the chassis, frame, or crumple zones have been affected. However, it can be repaired and returned to the road. Once repaired, it must be re-registered with the DVLA.
Cat S replaced the old "Cat C" category. There's no legal requirement for an inspection after repair, which is why buying a repaired Cat S requires caution.
Examples: Front or rear-end collisions affecting the chassis, bent subframes, damaged suspension mounting points.
Category N - Non-Structural Damage (Repairable)
The car has no structural damage. The write-off is due to cosmetic damage (panels, bumpers, lights) or mechanical problems (engine failure, gearbox issues). It can be repaired and returned to the road.
Cat N replaced the old "Cat D" category. These are generally considered safer purchases because there's no structural integrity concern - just components that need replacing.
Examples: Vandalism damage, stolen and recovered with damage, engine failures, flood damage (non-structural), hail damage.
How Write-Off Categories Affect Your Car's Value
Here's the reality: a write-off marker permanently affects your car's value. Even if the car is perfectly repaired and drives like new, that marker follows it forever on HPI checks and DVLA records.
| Category | Typical Value Reduction | Insurance Impact |
|---|---|---|
| Cat N (Non-Structural) | 20-30% less | 10-20% higher premiums |
| Cat S (Structural) | 30-40% less | 20-30% higher premiums |
| Cat D (Old system) | 25-35% less | Similar to Cat N |
"We've seen customers receive £2,000+ more from Cash Your Car compared to their scrap yard quote, simply because we understand the parts market for specific models - including write-offs."
— Cash Your Car Valuations Team
What Are Your Options With a Write-Off?
Option 1: Keep & Repair
- Buy the car back from your insurer (usually 10-30% of pre-accident value)
- Arrange your own repairs
- Re-register with DVLA (Cat S only)
- Consider getting a professional inspection
Best for: Cars with minor damage where repair costs are low
Option 2: Take the Payout
- Accept the insurer's settlement
- Insurer keeps the car
- Use payout towards a replacement
- Negotiate if offer seems low
Best for: Older cars or when repair costs are high
Option 3: Sell to a Specialist (Like Us)
If you already own a Cat N or Cat S vehicle and want to sell it, you have options beyond private sales (where buyers are wary) or trade-ins (where dealers lowball).
- We assess the actual vehicle value, not just the category
- No hassle of private sale viewings and negotiations
- Free collection and same-day payment
Cat C vs Cat S: What Changed in 2017?
In October 2017, the ABI overhauled the write-off category system. Here's how the old categories map to the new ones:
| Old Category | New Category | What Changed |
|---|---|---|
| Cat A | Cat A | No change - still means scrap only |
| Cat B | Cat B | No change - shell crushed, parts salvageable |
| Cat C | Cat S | Now explicitly means "structural damage" |
| Cat D | Cat N | Now explicitly means "non-structural" |
Important: If your car was written off before October 2017, it will still show its original category (Cat C or Cat D) on HPI checks. The categories weren't retrospectively changed.
Frequently Asked Questions
Got a Write-Off to Sell?
Whether it's Cat N, Cat S, or the old Cat C/D, we buy all write-off categories. Get a fair quote based on your vehicle's actual value, not just the marker.