Do Modifications Affect Your Car Insurance?
Almost any change to the car is something your insurer needs to know. Declaring it is not optional, and getting it wrong can cost you the whole claim.
Modifications almost always affect your insurance. A change to the car is a material fact you must declare; performance mods usually raise the premium, and an undeclared modification can let the insurer void the policy or refuse a claim. This is separate from whether the mod is road-legal.
Insurance and road-legality are two different questions. A part can be perfectly legal and still need declaring. The safe rule is simple: if you changed the car from standard, tell your insurer.
Why you have to tell them
A modification changes the risk the insurer is pricing, so it counts as a material fact. Under the Consumer Insurance (Disclosure and Representations) Act 2012 you must take reasonable care not to misrepresent your car, which means answering questions about modifications honestly and completely. Declare the change before you drive on the new setup, not after a claim.
What counts as a modification
More than most people expect. Performance parts (a remap, exhaust, intake, turbo work), suspension and wheels, brakes, body styling, and window tint all count. So do changes made by a previous owner: if you bought the car already modified, those mods are still yours to declare. Even security additions count, though some of those can lower a premium rather than raise it.
What happens if you do not
If an undeclared modification is relevant to a claim, the insurer can reduce the payout, refuse it outright, or treat the policy as though it never existed and void it. That can leave you personally liable, and driving on a voided policy is itself an offence. Keep a record of every change and the date you told your insurer. Whether a specific part is also road-legal is a separate question, covered part by part in the guides.
The conditions that matter
- !A modification is a material fact you must declare to your insurer.
- !Mods made by a previous owner still need declaring.
- !Performance mods usually raise the premium; some security mods lower it.
- ✕An undeclared mod can void the policy or get a claim refused.
Sources
General guidance, not legal advice. Insurance terms and road-legality vary by insurer and by exact vehicle and change over time; confirm with your insurer and the latest DVSA/GOV.UK guidance before modifying.