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Car Insurance Modifications UK

Which vehicle modifications you must declare, how they affect your premium, and the risks of not declaring them.

Quick Answer

Any change to your car's manufacturer specification, from performance upgrades to cosmetic changes like alloy wheels or window tints, is generally considered a modification that must be declared to your insurer. Undeclared modifications are a common reason claims are reduced or rejected. Some modifications increase premiums due to higher performance, theft or repair-cost risk, while others may have little to no effect.

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Table of Contents

What Counts as a Modification?

A modification is any change to your vehicle from the manufacturer's original specification. This includes obvious performance changes, but also many changes that owners don't always think to declare.

  • Engine tuning or remapping
  • Exhaust system changes
  • Suspension or brake upgrades
  • Alloy wheels not fitted as standard
  • Body kits, spoilers or styling changes
  • Window tinting beyond factory specification
  • Upgraded audio or in-car technology systems

Why Modifications Matter to Insurers

Modifications can affect a vehicle's performance, value, and attractiveness to thieves, all of which influence risk. Performance modifications may increase the likelihood or severity of an accident, while high-value cosmetic changes can increase the cost of a claim, and some modifications increase the risk of theft.

How Modifications Affect Your Premium

Performance Modifications

Engine, exhaust and suspension changes that increase power or alter handling are typically viewed as higher risk and can noticeably increase premiums.

Cosmetic Modifications

Purely cosmetic changes, such as styling kits or upgraded wheels, may have a smaller impact but can still affect premiums, particularly if they increase the vehicle's value or theft appeal.

Expert Tip: If you're planning multiple modifications, declare each one as it's made rather than waiting until renewal, since undeclared changes in the meantime could affect any claim made before your next renewal.

Risks of Not Declaring Modifications

Warning: Failing to declare a modification is one of the most common reasons car insurance claims are reduced or rejected. Even a modification that seems minor to you may be considered material by your insurer.

If undeclared modifications come to light during a claim, insurers may apply proportionate reductions to any payout, adjust terms going forward, or in serious cases treat the policy as void from the point the modification was made.

Finding Insurance for Modified Cars

Standard insurers may still cover lightly modified vehicles, but for more heavily modified cars, specialist modified car insurers may offer more suitable and competitively priced cover, as they have more experience assessing this type of risk.

Frequently Asked Questions About Car Insurance Modifications UK

Do I need to declare alloy wheels as a modification?

If they are not part of the original manufacturer specification, yes, they should generally be declared even though the impact on your premium may be small.

Will modifying my car always increase my premium?

Not always, but many modifications, particularly performance-related ones, tend to increase perceived risk and therefore premiums.

What happens if I don't declare a modification?

This can lead to a claim being reduced or rejected, or the policy being treated as void from the date of the undeclared change.

Can I get insurance for a heavily modified car?

Yes, specialist modified car insurers often provide more suitable cover and pricing for heavily modified vehicles than mainstream insurers.

Do I need to declare modifications made before I bought the car?

Yes. Any modification present on the vehicle, regardless of when or by whom it was made, should generally be declared to your insurer.

Conclusion

Whether cosmetic or performance-related, modifications should always be declared to your insurer to keep your cover valid. While some modifications increase premiums, comparing specialist modified car insurers can help you find suitable cover that reflects your vehicle accurately.

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