What is the difference between Category N and Category S?

Category N and Category S are both used to classify insurance write-offs in the UK, and the key difference between them comes down to whether the vehicle's structural integrity was affected.

The two categories:

• Category N (non-structural damage) — the car was written off due to damage that doesn't affect the structural frame, such as damage to bumpers, panels, glass, or interior components. The vehicle can typically be repaired and returned to the road without any structural concerns.
• Category S (structural damage) — the car sustained damage to a structural component, such as the chassis, floor pan, or suspension mounting points. It can still legally be repaired and put back on the road, but the repair needs to properly address the structural damage, not just the cosmetic parts.

Why the distinction matters:

Structural damage is inherently more serious, since it can affect how the car behaves in a future collision if not repaired to a proper standard — this is the main reason Cat S cars are viewed with more caution than Cat N cars by buyers, insurers, and valuers alike. Both categories mean the car was written off by an insurer as uneconomical to repair at the time, but the type of damage — and therefore the standard of repair needed to make the car genuinely safe again — differs significantly between the two.

Neither category means a car can't be legally driven once repaired, but the risk profile, insurance implications, and resale value differ meaningfully between them, which is worth understanding before deciding whether either is a car you're comfortable buying.