What HMRC needs in a mileage log

If you claim mileage as a sole trader, HMRC can ask how you got to your figure. A mileage log is the answer. HMRC’s own guidance says the flat rate claim should be backed by a record of business mileage kept at the time, not pieced together from memory in January.

What to write down for each journey

HMRC doesn’t give you a form to fill in, but a log that answers these questions for every business trip will stand up:

1. The date of the journey.
2. Where you started and where you finished.
3. How many miles it was.
4. What it was for, such as “quote at 12 High Street” or “wholesaler for cable”.
5. Which vehicle, if you have more than one.

Add up the business miles for each tax year (6 April to 5 April), so you know when you pass 10,000 miles and the rate drops from 55p to 25p. See HMRC mileage rates for the rates.

Which trips go in the log

• In: driving to customers and sites, to quote, to the merchant or wholesaler, and between jobs.
• Out: personal trips, and your ordinary commute to a regular place of work, such as a yard you go to every day.
• Out: a trip that’s partly personal, like a detour to the school run on the way to a job. HMRC says a journey with a private purpose as well doesn’t qualify.

Why “as you go” matters

A log written up months later tends to be round numbers and guesses, and that’s what draws questions. Writing each trip down on the day, or letting an app do it, gives you dates, places and miles that match your diary and your invoices.

How long to keep it

Keep your mileage log with the rest of your business records for at least 5 years after the 31 January deadline for that tax year. So the log for 2026 to 2027, which goes on the return due by 31 January 2028, should be kept until at least 31 January 2033.

If records are lost and you can’t replace them, HMRC asks you to do your best to give figures and say they’re estimates when you file.

If you claim actual van costs instead

You still need to know your business miles, because you can only claim the business share of your running costs. Note the odometer reading at the start and end of the tax year, and your business miles from your log give you the share. See van mileage allowance or actual costs.

How Kev keeps your log

With Kev’s mileage tracker, you tap start when you set off and stop when you arrive. Kev saves the date, where you started and finished, the road distance, and what the trip was for, and prices it at the HMRC rate for that tax year. Forgot to tap start? Add the journey by hand. Your mileage report downloads as a spreadsheet for your accountant.

Sources

• HMRC Business Income Manual: simplified expenses for motor vehicles
• gov.uk: Simplified expenses, vehicles
• gov.uk: How long to keep your records