What counts as a car modification for insurance?

Broadly, anything that changes the car from the manufacturer's standard specification: window tints, alloy wheels, body kits, exhausts, remaps and performance upgrades, suspension changes, wraps and respray colour changes, towbars, and some accessibility adaptations. When in doubt, tell the insurer and let them decide.

ModificationsUK car insurance·4 min read·25 Aug 2026

Do tinted windows need to be declared to your insurer?

Q: Do tinted windows need to be declared to your car insurer?

If the tint wasn't fitted by the manufacturer, yes. Most UK insurers treat aftermarket window tints as a modification, and undeclared modifications are one of the most common reasons car insurance claims fail — around 16% of rejected UK claims involve them.

Q: Will declaring a modification always raise my premium?

Not always — the effect depends on the modification and the insurer, and some changes make little or no difference to the price. Not declaring is the expensive option: an undeclared modification discovered at claim time can lead to a reduced settlement or a rejected claim.

Posted by Alesha de la ChevotiereFounder, PolicySnap

If the tint wasn't fitted by the manufacturer, yes — most UK insurers treat aftermarket window tints as a modification, and undeclared modifications are one of the most common reasons claims fail.

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Around 16% of rejected UK car insurance claims involve undeclared modifications.

Source: brumble.co.uk industry data

What counts as a modification?

Broadly, anything that changes the car from the manufacturer's standard specification. Common ones include:

Window tints (when not factory-fitted)
Alloy wheels, body kits and spoilers
Exhausts, remaps and performance upgrades
Suspension changes
Wraps and respray colour changes
Towbars and some accessibility adaptations

If you're not sure whether something counts, tell the insurer and let them decide — a two-minute call beats an argument at claim time.

Are tinted windows even legal in the UK?

There are legal limits at the front of the car: the front windscreen must let at least 75% of light through, and the front side windows at least 70%. There are no light-transmission rules for rear side windows or the rear windscreen. But legal and declared are different questions — a tint can be perfectly road-legal and still need declaring to your insurer.

Will declaring a modification always raise my premium?

Not always. The effect depends on the modification and the insurer — some changes make little or no difference to the price. Not declaring is the expensive option: an undeclared modification discovered at claim time can lead to a reduced settlement or a rejected claim.

I bought the car with the tints already on it — do they still count?

Usually yes. If a previous owner fitted them, they're still a departure from the factory specification, and most insurers want to know. Mention them when you take out or renew the policy.