How is car insurance calculated in the UK?

The three layers of a UK car insurance price

Every UK motor quote is assembled the same way. First the insurer calculates a risk premium — a statistical estimate of what your claims will cost it over the next twelve months, produced by a pricing model trained on tens of millions of historic policies and claims. The ABI’s tracker alone draws on around 28 million policies a year. That model takes your answers to the quote form, matches them against people who look like you, and outputs an expected claims cost.

Second, the insurer adds its own expense loading: claims handling, reinsurance, broker or comparison-site commission, regulatory capital and profit margin. Third, Insurance Premium Tax at 12% is applied to the total — on a £600 policy that is about £64 of the price, and it is unavoidable regardless of how good a driver you are. If you then choose to pay monthly, a credit agreement is layered on top at a typical 20–30% APR, which is why the same policy can cost £738 spread over twelve instalments instead of £600 in one go.

The critical thing to understand is that nothing in this process is a judgement about you personally. An insurer has no idea whether you are a careful driver. It only knows the claims record of the group its model places you in — which is why two people with identical driving ability can be quoted prices that differ by a factor of five.

The rating factors insurers actually use

UK insurers use twenty-plus rating factors, but they are not equal. These are ordered roughly by how much they move a price in 2026:

1. Age and driving experience — the dominant factor. A 17-year-old averages £2,847 against about £600 for a driver in their late thirties. Premiums fall steeply to age 21, flatten through middle age, and tick up again past 75.
2. Claims and conviction history — at-fault claims typically add 20–50% for three to five years. DVLA endorsements must be declared for five years (eleven for drink-driving codes such as DR10) and carry uplifts from roughly 5% for a single SP30 to 100%+ for DR10.
3. No-claims discount — the largest legitimate discount available. Five years typically cuts 45–60% off the base price; nine or more years reaches the maximum most insurers offer.
4. Postcode — priced at full postcode level, not town. Theft rates, claims frequency, traffic density and even the local repair-cost index feed in. The same driver and car can differ by 70% across the country.
5. The car itself — via its insurance group. Models registered before August 2024 sit on the Thatcham/ABI 1–50 scale, assessed against roughly 125 vehicle attributes. Newer model ranges also carry a Vehicle Risk Rating, scoring Performance, Damageability, Repairability, Safety and Security from 1 to 99 each.
6. Annual mileage — exposure to risk. Understating it to save money is a misrepresentation that can void a claim.
7. Where the car is kept overnight — garage, driveway and street each price differently, and it is checked against the address, not just taken on trust.
8. Occupation and employment status — a proxy for mileage patterns, hours driven and parking. Job titles are matched to claims data, which is why “chef” and “kitchen manager” can produce different prices for the same job.
9. Cover type and voluntary excess — comprehensive is often cheaper than third-party-only in the UK, because third-party cover attracts a higher-risk applicant pool.
10. Named drivers — adding an older, experienced driver can lower the price legitimately. Declaring them as the main driver when they are not is fronting, and it is fraud.
11. Modifications — anything that changes performance, appearance or security must be declared, including wheels and remaps.
12. Policy start date — buying 21–26 days ahead of cover typically prices lower than buying on the day, because last-minute buyers claim more.

What insurers cannot use is just as important. Since the EU Gender Directive took effect in December 2012, gender cannot be used as a rating factor in UK motor insurance. Ethnicity, religion and disability are similarly excluded. Since January 2022 the FCA has also banned price walking — quietly raising a loyal customer’s renewal above the equivalent new-business price. Your renewal quote must now be no higher than what an equivalent new customer would be offered through the same channel. The FCA estimated that six million customers would have saved £1.2 billion in a single year had these rules already existed.

Common questions about how premiums are calculated