Are car modifications covered by car insurance?
Not automatically — and this is where a large number of UK drivers unknowingly invalidate their cover. Are modifications covered by car insurance? The answer depends on what you’ve changed, whether you’ve declared it, and which insurer you’re with. Declare every modification from factory specification — without that, your cover is at risk. Failure to declare a modification means that if you make a claim, the insurer may void the policy or reduce the payout on the basis of non-disclosure.
Whether a modification is actually covered, and at what cost, depends entirely on the type of modification and the insurer. Some modifications are straightforward to cover; others require a specialist policy.
What counts as a modification?
A modification is anything that changes the vehicle from its manufacturer’s standard specification — not just performance changes. Our full UK car modification guide covers this in detail, but as a starting point, here’s how common modification types are typically treated by insurers.
| Category | Examples | Insurance impact |
|---|---|---|
| Performance | Engine tune/remap, turbo upgrade, exhaust change, suspension lowering | Usually significant premium increase — some insurers won’t cover |
| Aesthetic / bodywork | Body kit, spoiler, custom paint, vinyl wrap, tinted windows | Moderate impact — must be declared, may add value to declared vehicle |
| Wheels / tyres | Alloy upgrade, non-standard tyre size, spacers | Moderate — affects vehicle value and potentially handling risk |
| Electronics / audio | Upgraded stereo, in-car screens, custom lighting | Usually minor if declared — expensive components need declaring for value |
| Safety / security | Dashcam, Thatcham alarm, tracker, reversing camera | Neutral to positive — security mods often reduce or maintain premium |
| Interior | Sports seats, custom upholstery, roll cage | Roll cage and harness systems have significant implications — specialist cover needed |
The disclosure rule — and what happens if you don’t
Your duty to disclose modifications applies both when you take out the policy and when you make a modification mid-policy. Adding a body kit in June on a policy that runs to November means you must call your insurer in June — not wait for renewal.
If you make a claim and the insurer discovers an undeclared modification that’s material to the claim, they can reduce the payout proportionately, or void the policy entirely under CIDRA 2012 for deliberate or reckless non-disclosure. This isn’t a theoretical risk — undeclared modifications are a well-known avenue for claim disputes.
Even modifications you didn’t fit yourself must be declared. Buy a used car with undisclosed modifications and you inherit the disclosure duty — the insurer won’t care who fitted them. This applies equally to structural changes that affect category ratings — if you’re unsure what you’re buying, it’s worth reading up on Cat N vs Cat S explained before you insure a used vehicle. Check any used car’s modification history before insuring it.
Modifications that can reduce your premium
Security-enhancing modifications are viewed positively by most insurers. A Thatcham-approved alarm, immobiliser or tracker can reduce your premium — particularly in high-theft postcodes. Many insurers look favourably on dashcams too, as the footage helps resolve disputed claims. Always declare these modifications and ask your insurer directly whether they’ll factor them into your premium.
When you need a specialist modified car policy
For significant performance modifications or highly customised vehicles, standard comparison site policies won’t provide adequate cover — either because the insurer won’t quote at all, or because the quote doesn’t accurately reflect the vehicle’s modified value.
Specialist modified car insurers underwrite based on the specific modifications made and their agreed value. Standard market value databases don’t account for a £3,000 engine tune or custom bodywork. Write the car off on a standard policy and you’ll likely receive less than it’s worth. Specialist insurers agree a value upfront, so you can argue the case before the claim — not during it.
For modified vehicles, it’s worth getting a quote from a specialist direct rather than relying on comparison sites — most specialist modified insurers don’t appear on aggregator panels. If you’re weighing up your options, our guide to car insurance direct vs comparison sites is worth a read before you start.
FAQ
Do I need to tell my insurer about car modifications?
Yes — any modification from the factory specification must be declared. Failing to do so can void your policy or reduce a claim payout.
Do modifications always increase my insurance premium?
Not always. Security modifications (alarms, trackers, dashcams) can reduce premiums. Performance and aesthetic modifications usually increase them.
What happens if I don’t declare a modification?
Your insurer can void the policy or reduce any claim payout on the grounds of material non-disclosure under CIDRA 2012.
Does a previous owner’s modification affect my insurance?
Yes — modifications made by a previous owner are still material facts you must declare when insuring the vehicle. Always check for undeclared modifications when buying used.
Can I insure a modified car on a standard policy?
For minor modifications, usually yes with a declared value adjustment. But for significant performance or structural modifications, a specialist modified car policy is usually required.
How Rooster can help
So, if you’re a safe driver wondering are modifications covered by car insurance, the right starting point is a policy that’s priced on how you actually drive — not just what your car looks like on paper. Rooster’s Test Drive uses your phone’s GPS and motion sensors to build a driving profile over around three weeks, then gets you the most competitive quote. Safe drivers can save up to 40%.
Also if you’re ever involved in an incident — modified car or not — Rooster’s free Accident Assist (www.joinrooster.co.uk/claim) gives you independent support to make sure you get the best possible outcome from any claim.
