Published 11 September 2025
Do car modifications affect your insurance?
We’re here to debunk modification myths and clear up what you can do to personalise your car, without impacting your car insurance…
What is a car modification?
A modification is defined as any change made to a car that alters it from the standard manufacturer or factory specifications. These changes range from cosmetic changes (alloy wheels) to practical enhancements (parking sensors).
It’s important to know the difference between an optional extra added to the car on ‘the factory floor’ and modifications which are made after the car leaves the factory.
Optional Extras added by the manufacturer are not considered modifications, but changes made afterwards are, so they may affect your insurance.
Do you need to tell your insurer if you modify your car?
Yes. Before making any changes to your car, you’ll need to let your insurer know your plans, so they can let you know if your cover would be affected.
Why? Well, some modifications make your car more powerful, which could increase the risk of having an accident, while others will increase the cost of your insurance due to the cost of repairing or replacing them. You’re also at risk of faulty parts or unreliable fitting, as it’s been done outside of the manufacturer.
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Are tinted windows a modification?
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Are side skirts a modification?
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Are decals a modification?
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Is a paint protection film (PPF) a modification?
Yes, so if you add a tint, it must remain within the legal limits. If your tinted windows are too dark, they could be considered illegal. The law states that the front side windows must let at least 70% of light through, while the windscreen must let at least 75% of light through. Cars first used before 1 April 1985 need to let 70% of light through both the windscreen and front side windows.
Yes, side skirts are considered a modification as they’re added after the car has left the factory floor, and alter the original design and aerodynamic characteristics of the vehicle.
Yes, decals are generally considered a cosmetic modification to a vehicle. Unlike mechanical or performance modifications, they mainly alter the appearance of the vehicle for personalisation or branding purposes.
Decals are usually made from thicker, more durable vinyl which means they’re larger and more complex to attach and align, which could pose a potential danger.
Yes, a PPF ( Paint Protection Film) is a transparent, durable film applied to the exterior surfaces of a vehicle to protect the paint from damage and is considered a modification because it can heavily impact repair costs to a damaged car.
Do I need to tell my insurer about Over-The-Air (OTA) updates?
Over-the-air monthly updates are covered as standard when you insure your electric vehicle with us, but if you or the previous owner paid for additional performance upgrades affecting speed or acceleration, please let us know. You'll only need to tell us once though, not every time you upgrade.
Do I need to tell my insurer about software updates?
We only need to know about software updates that increase performance or add new functionality to the car. We don’t need to know about updates to the infotainment system, or similar.
Can I insure a modified car?
When you take out your policy, we’ll ask you about any changes to the standard specification of your car. You’ll need to tell us about any modifications - even if you didn’t make them. Once we have all the information, we can make a decision on the cover we can offer and how much it’ll cost. The key is to be open and honest, to avoid any issues down the line if you need to claim.
Are cosmetic customisations covered?
Cosmetic customisations are still considered as modifications to a vehicle, so they may impact your insurance. For more information on what’s covered, take a look at our article about what your insurer needs to know about modifications to your car..
Do I need to tell my insurer about safety modifications?
We take things like dashcams, locking devices, immobilisers and parking sensors into account when setting up your car insurance price, so make sure you let us know.
Generally, these safety and security features reduce the risk of accident or theft, so, it’s a good idea to let your insurer know when you add any extra safety tech to your car.
If your insurer doesn’t know about a modification you’ve made (or intend to make) to your car, they may not be able to help when you need to make a claim.
Is remapping a modification?
Yes, remapping is considered a modification. It’s difficult for insurers to tell if a car is remapped, but you should inform your insurance provider if you know it is.
If you’re in a car accident and the police can see your engine has been remapped, you could be in big trouble, and your insurer won’t be able to pay out.
Will your car insurance policy be invalid if you don’t declare modifications?
Although this is at the discretion of the insurer, there’s a definite risk. Not declaring modifications puts you at risk of your policy becoming invalid.
How can I check a used car for modifications before I buy it?
Before buying a used car, ask the seller if it’s been modified and carry out the following checks to make double sure:
- Give the car a physical inspection in broad daylight, so you can check for any changes, flaws, or damage.
- Check for exhaust, pipe, and filter customisations, because if these were made with low-quality alternatives, they can wear off and will quickly need replacing.
- If you notice tyres with multiple brands, this could be a sign of modification.
- If there are tinted windows, do they look too dark to meet the legal requirements described earlier?
If you’re not sure after checking, bear in mind the possibility of legal issues and invalid insurance if there are modifications you don’t know about.
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