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Modified car insurance 

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What is modified car insurance?

Modified car insurance is what you take out to cover your car if you’ve had it altered in any way. It’s a standard car insurance policy, however, the premiums will also factor in any changes that have been made to the vehicle..

This is why if you do make any custom changes – or you purchase a vehicle that has been customised from the factory model – you should let your insurance provider know. Failure to do so could result in your policy being invalid when you come to make a claim.

How does modified car insurance work?

  • Always consult your insurance company before you make any modifications. They can tell you what impact, if any, the changes will make to your policy and premiums

  • Insurers believe that modifications done outside the factory cannot be guaranteed and may compromise the integrity of the vehicle which can result in an increase in your premiums

  • Insurers use car insurance groups to set premiums and modifications can potentially void your rating

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What counts as a car modification?

The most popular car modifications in the UK are alloy wheels, suspension changes and exhaust system changes. Other common customisations include tinted windows, tow bars and engine management systems.

Upgrades and modifications such as  personalised number plates may not directly affect your car insurance premium, but you will need to notify your insurer if you make them, and an admin fee may be charged to update your records.

Sarah Tooze

Our expert says


Before making any modifications to your car, check whether they are legal. There are rules about tinted windows and noise restrictions for altered exhausts, for instance. If you decide to have your engine remapped you need to ensure it doesn’t make your car’s emissions non-compliant. Even something as simple as upgrading your wheels counts as a car modification, and if they’re more expensive they’ll cost the insurer more to replace and might be attractive to thieves.

- Sarah Tooze, Car & Van Insurance Expert

What is covered by modified car insurance?

Insurance policies for modified cars offer everything you’ll get with most car insurance policies – depending on the level of cover you take out, you should be able to get cover for:

  • Icon-car-insurance-50x50

    Your vehicle

    A fully comprehensive car insurance policy should provide cover for you and your vehicle against a range of insured events, including fire, theft, and more

  • icon-service-50


    This cover will also extend to any modifications you’ve had made or installed – so long as you’ve declared them to the insurer

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    Third-party damage

    You’ll also be covered for any damage you do to a third party, their vehicle, or their property

  • Multicar-M

    Any extras you choose

    Car insurance policies also offer a range of extra features like car key cover, windscreen cover, and breakdown cover – some are included as standard, while others are usually available at an extra cost

Is insurance more expensive for modified cars?

The way modifications can affect your car insurance price depends on a number of factors. Typically, however, modifying your car will increase the cost of your car insurance.

Reasons for increased price:

  • Increased risk of accidents or theft

  • Increased value of the car

  • Insurers can't guarantee the quality of any modifications


  • Modifications that make your car safer may reduce your premiums

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How to get cheaper modified car insurance cover?

If you’ve had your car modified, you might want to consider the following to help balance the higher insurance costs:

  • 1

    Paying annually

    Paying your car insurance premiums annually usually works out cheaper than spreading the cost over 12 months

  • 2

    Volunteering a higher excess

    Paying a higher voluntary excess tells insurers you’re unlikely to bother with small claims that wouldn’t be worth the cost

  • 3

    Build a no-claims discount

    If you can go for over a year without claiming you’ll start to accumulate a no-claims discount on future premiums

  • 4

    Reduce your mileage

    The less time you spend on the road the lower your chances of being involved in an accident, so giving a lower estimated mileage can cut your premiums

  • 5

    Consider pay-as-you-go:

    Pay-as-you-go car insurance lets you pay for cover either by-the-mile, by-the-hour or based on your driving, and can be a cheaper alternative for some drivers

  • 6

    Avoid auto-renewing

    You might be able to find a cheaper deal on your car insurance if you compare quotes rather than auto renewing your policy

Car insurance is almost always more expensive for younger drivers, and this is true for modified cars too. Unfortunately for young drivers, they are associated with a higher claim risk due to their inexperience on the road – as a result, insurers charge higher premiums.

If you’ve modified a car after purchasing it, you just need to inform your insurer of all the work that has been done to the car so they can factor it in when deciding your premiums.

Not all modifications push up car insurance premiums. If you install additional security measures to prevent your car from being stolen, such as an alarm, you may see your premiums fall because your provider considers you a lower risk.

The same holds true for immobilisers and tracking devices but call your insurer to check whether a reduction will be made and how much it will be.

You can customise your vehicle whenever you choose, but you must notify your insurance company who will then decide on how the modifications affect your premiums. 

The important thing to understand is that the existing insurance policy covers your car for its original condition. Once that is changed, the policy needs to be adjusted to suit or you risk invalidating the insurance.

There are some cases where you may need a specialist modified car insurance policy.

Most minor, legal modifications can be covered by standard car insurance. However, some modifications can affect which insurance rating group your car fits into. This means that your cover may be more expensive or, in some cases, a modification could void your cover, especially if you fail to tell your provider about it.

If you have plans to make modifications to your car there are specialist policies available that will cover both big and small modifications with no hassle. These special policies are priced differently to standard car insurance and may have different terms so it's up to you to decide whether the cover is worth the cost.

At MoneySuperMarket, we do not offer quotes for specialist policies. However, we can find you quotes for car insurance providers that will cover existing modifications made to your car.

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