How car modifications affect your car insurance
Learn about car modifications and what you need to declare with Tesco Car Insurance.
Published: 25 May 2026
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Need insurance for a modified car?
If you’ve changed your car in any way, you might need to tell us. Or your insurer, if it’s not us. But how do you know when to declare something?
In this guide, we take the guesswork out of modified car insurance. So you can get the right cover now and avoid problems later - especially if you need to make a claim.
We’ll go over:
- what modifications affect car insurancewhat modifications affect car insurance
- car modifications that don’t affect car insurancecar modifications that don’t affect car insurance
- the impact of not declaring modifications to your insurerthe impact of not declaring modifications to your insurer
What do we mean by a car modification?
Here’s a simple definition of a car modification for your car insurance:
- Any change to your car that makes it different from the standard version of the car that left the factory.Any change to your car that makes it different from the standard version of the car that left the factory.
That typically includes:
- most paid upgrades - whether they were done when you bought the car or added later most paid upgrades - whether they were done when you bought the car or added later
- paid-for over-the-air updatespaid-for over-the-air updates
- any modifications you’ve done yourselfany modifications you’ve done yourself
Why we need to know about car modifications
We ask about modifications when you apply for Tesco Car Insurance. You should also tell us about any modifications you plan to make after you’ve taken out cover with us.
That’s because changes to your car can affect:
- safetysafety
- performanceperformance
- the risk of theftthe risk of theft
- repair costsrepair costs
Knowing how your car’s been modified helps us to work out your cover and the right price for your policy.
What are the different types of car modification?
It can make it easier to declare changes to your car if you know what the different types of modifications are.
For car insurance, a modification is either an optional extra or aftermarket.
Optional extras
These are paid upgrades you choose when buying the car new. They’re fitted by the manufacturer or dealer.
Examples:
- Larger alloy wheels offered by the manufacturerLarger alloy wheels offered by the manufacturer
- Built-in sat nav or upgraded sound systemBuilt-in sat nav or upgraded sound system
- Metallic paintMetallic paint
- Parking sensors added by the dealerParking sensors added by the dealer
These aren’t usually classed as modifications, but some insurers still ask you to list them. It’s always best to check with us or include them when you get a Car Insurance quote.
Aftermarket modifications
These are changes added after the car was built - often by a garage, specialist or previous owner. You might even have made the modifications yourself.
These should always be declared.
What modifications affect car insurance?
Wondering which modifications you need to declare on your car insurance?
The simple answer is this:
- You should declare all modifications to your car. And we’ll let you know if and how they affect your cover.You should declare all modifications to your car. And we’ll let you know if and how they affect your cover.
Here are some of the most common car modifications.
Performance changes
- Engine remapping or tuningEngine remapping or tuning
- Turbo or supercharger addedTurbo or supercharger added
- Sports exhaustSports exhaust
- Changes to suspension or brakesChanges to suspension or brakes
Appearance changes
- Body kits* and spoilersBody kits* and spoilers
- Non-standard paintwork or wrapsNon-standard paintwork or wraps
- Lowered suspensionLowered suspension
- Non-standard alloy wheelsNon-standard alloy wheels
*People often ask, “Do body kits increase insurance premiums?” The answer is, yes, they can. So always declare them.
Wheels and tyres
- Larger or wider wheels than standardLarger or wider wheels than standard
- Low-profile tyres not offered by the manufacturerLow-profile tyres not offered by the manufacturer
(If you’ve bought tyre and alloy insurance, you still need to tell your insurer about modified wheels.)
Interior and tech
- Upgraded sound systemsUpgraded sound systems
- Screens added to the dashboardScreens added to the dashboard
- Custom seats or steering wheelsCustom seats or steering wheels
Security changes
- Aftermarket alarms or immobilisersAftermarket alarms or immobilisers
- Trackers not fitted by the manufacturerTrackers not fitted by the manufacturer
Modifications for disability or mobility needs
If your car’s been adapted to help with a disability, you still need to tell your insurer.
Examples:
- Hand controlsHand controls
- Wheelchair accessWheelchair access
- Pedal modificationsPedal modifications
Modifications for disability or mobility needs are usually fine. There shouldn't be a problem with cover. By declaring them, though, you’ll make sure the car’s got the right cover and can be repaired correctly if you make a claim.
What you need to know: declaring car modifications
Here’s why you need to declare car modifications to your insurer and how to do it. And what to remember after you’ve bought your car insurance policy.
Why you must declare car modifications
If you don’t tell us - or your insurer, if it’s not us - about any modifications:
- your policy might be voidyour policy might be void
- your policy could be cancelledyour policy could be cancelled
- claims might be reduced or refusedclaims might be reduced or refused
- you might find it harder or more expensive to get insurance lateryou might find it harder or more expensive to get insurance later
What is classed as modifications on car insurance matters - even if the change was made by a previous owner.
How to declare modifications to your insurer
Declaring changes to your car is usually quick and straightforward. With Tesco Car Insurance, you just need to give us a call.
Get a Car Insurance quote with modifications
Call our friendly, UK-based Customer Service team. They’ll be happy to help.
Lines are open Monday to Friday 8am-8pm, Saturday and Sunday 9am-2pm.
Calls may be recorded.
*This number may be included as part of any inclusive call minutes provided by your phone operator.
What to tell us when you call
When you phone for a Car Insurance quote:
- List all known modifications, even if they seem smallList all known modifications, even if they seem small
- Be honest if you’re not sure when or how a change was madeBe honest if you’re not sure when or how a change was made
Some insurers might ask for details using a modified vehicle report form, especially for more complex changes.
Modifying your car after buying Car Insurance
If you’re adding a modification after taking out Car Insurance with us:
- Tell us before you do it or as soon as it’s fittedTell us before you do it or as soon as it’s fitted
- We’ll let you know if it affects your price or coverWe’ll let you know if it affects your price or cover
Just give us a call to get it sorted.
Lines are open Monday to Friday 8am-8pm, Saturday and Sunday 9am-2pm.
Does having modifications always increase insurance?
Not always, but sometimes.
It depends on:
- the type of modificationthe type of modification
- whether it affects performancewhether it affects performance
- how much it increases repair or replacement costshow much it increases repair or replacement costs
Cosmetic changes might have little impact, but performance upgrades often do.
You can learn more about the factors affecting your premiums in our guide - What affects your car insurance premiums.
Tesco Car Insurance - helping you to save you money
If car modifications are pushing up the price of your policy, it’s worth thinking about the ways we can help you to save.
Voluntary excess
If you can afford a higher voluntary excess, it can help to lower the cost of your cover.
You can choose or amend your voluntary excess:
- when you take out cover with uswhen you take out cover with us
- if you change your carif you change your car
- when your policy renewswhen your policy renews
You can learn more about your voluntary excess in our guide - How does voluntary excess work?
Clubcard discount
Tesco Car Insurance comes with Clubcard Prices. That means you’ll get money off just by having a Tesco Clubcard.
If you don’t already have one, find out about Clubcard.
With our special offer, you can get 15% off Car Insurance with your Clubcard until 30 June 2026. Excludes add-ons and optional extras.
No claims discount
If you’re a new or renewing customer, your no claims discount can also help you to save money.
You can learn about no claims discounts in our guide - No claims discounts explained.
Why choose Tesco Car Insurance?
Looking for car insurance with modifications? It’s easy to find out what the options are and compare cover with Tesco Car Insurance. And we’re here to help and support you too.
Here are just a few of the reasons to choose us:
- UK-based customer serviceUK-based customer service
- 99% of Car Insurance claims paid (Jan-Dec 2025)99% of Car Insurance claims paid (Jan-Dec 2025)
- Save money with your ClubcardSave money with your Clubcard
You can choose from different levels of cover - Gold, Silver and Bronze. And you can add optional extras like Breakdown Cover and Key Cover to get more cover for an additional cost.
You can learn more about optional extras in our guide - Car insurance add-ons and extras.
Key takeaways - car modifications and car insurance
- A modification is any change from the car’s standard factory setupA modification is any change from the car’s standard factory setup
- Paid upgrades and aftermarket parts usually need to be declaredPaid upgrades and aftermarket parts usually need to be declared
- If in doubt, declare it when applying for car insurance - it’s the safest optionIf in doubt, declare it when applying for car insurance - it’s the safest option
- Being open and honest helps to protect your cover and any future claimsBeing open and honest helps to protect your cover and any future claims
Shopping for modified car insurance or updating your policy? Take a few extra minutes to list the changes to your car. It can save a lot of hassle later on.
Help for Car Insurance customers
Find out how to manage your policy, get in touch or make a claim if you’re a Tesco Car Insurance customer.
Important Information
About car insurance from Tesco Insurance
Tesco Car Insurance is arranged and administered by Tesco Insurance and is underwritten by Tesco Underwriting Ltd.
Optional extras Insurers:
- Motor Legal Protection is underwritten by AmTrust Specialty Limited.Motor Legal Protection is underwritten by AmTrust Specialty Limited.
- Breakdown Cover is underwritten by RAC Insurance Ltd.Breakdown Cover is underwritten by RAC Insurance Ltd.
- Keycover is underwritten by AA Underwriting Insurance Company Ltd. Claims are handled by Keycare.Keycover is underwritten by AA Underwriting Insurance Company Ltd. Claims are handled by Keycare.
- Upgraded courtesy car cover is underwritten by Tesco Underwriting Ltd.Upgraded courtesy car cover is underwritten by Tesco Underwriting Ltd.
You’ll find complete details of the cover, monetary limits, exclusions, excesses and terms in our policy documents.
Before you buy a Car Insurance policy
Before you buy your Tesco Car Insurance online, please read the policy documents to ensure that the policy you select meets your needs. The policy booklet and product information documents outline the benefits, limitations and exclusions that will apply to your cover.
Learn more about Car Insurance
Compare our Gold, Silver and Bronze comprehensive cover and save money with your Clubcard. For drivers aged 21 and over.
Not a Clubcard member? It’s free and it saves you money. Join now.