The key distinction
Estimate the car’s coming policy year, not just your own commuting. Add regular return journeys, occasional trips and the use made by other drivers. Keep the assumptions so you can revisit them.
Choose the period and the unit.
Write the intended policy start and end dates at the top of your worksheet. Use miles throughout, or convert kilometre readings before combining them. Treat one-way distance and return-trip distance as different entries so you do not accidentally halve or double a regular journey.
Aviva’s mileage guide suggests building an estimate from regular journeys and checking historical mileage. Use history as a cross-check, not a reason to ignore a changed working pattern or new driver. [1]
Add separate journey categories.
Start with commuting, then shopping, school or nursery trips, leisure, visiting relatives and holidays. Use the number of weeks each routine will actually happen rather than multiplying every activity by 52. Avoid double-counting: a supermarket stop already included in a commute needs only its additional distance.
Represent changes as scenarios.
In that example, adding one more 20-mile commuting day for each of 46 weeks adds 920 miles, taking the estimate to 5,560. This is a transparent higher-use scenario—not a percentage added without explanation. A new weekly journey is easier to account for explicitly than to hide inside an arbitrary buffer.
Compare the estimate with a plausible recent period and investigate large differences. You may have a good reason, such as retirement or a second household car. Note that reason. Ask the provider how it expects an uncertain estimate to be expressed; this worksheet does not decide which answer or mileage band its form requires.
Read the insurance question literally.
Check whether the form asks for the vehicle’s total use, personal use or business miles separately. Take reasonable care with the information requested. The Financial Ombudsman Service explains that the clarity of the question and the care taken with an answer matter in a misrepresentation dispute. [2]
Questions to take away
- Have all drivers and both directions been counted?
- Have term-time and working weeks been distinguished from a whole year?
- Have overlapping journeys been counted only once?
- Does a change in journey purpose also need a class-of-use check?
- Have you retained the assumptions and date of your estimate?
Sources & revision.
- [1]How your mileage impacts your car insurance (external website)
Aviva · Source checked 14 October 2026
Mileage declaration and estimating guidance.
- [2]Misrepresentation and non-disclosure (external website)
Financial Ombudsman Service · Source checked 14 October 2026
Reasonable care, materiality, policy changes and complaint handling; not an individual decision.
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