Keeping a mileage log for your tax return

The mileage claim is simple to work out and easy to lose. It rests on whether you can show which journeys it covers. Here is what belongs in the log, and how to keep it without setting time aside for it.

What belongs in every entry

The date. The time you set off and arrived. Where you drove from and to. Who or what you visited — client, site, supplier. The miles travelled. Whether the journey was business or private. Who was driving.

HMRC does not prescribe a form, but to claim the approved mileage rate you must be able to show the business journeys behind it: when, where and how far.

As you go, not afterwards

A log that was clearly written up months later, with round numbers and the same route every week, is weak evidence. HMRC expects a contemporaneous record — one kept as the journeys happen.

This is where an app does the real work: the phone notices that you drove, and you confirm the purpose with one tap while you still remember what the journey was for.

The rate and the 10,000-mile step

For the 2026/27 tax year HMRC's approved mileage rate for cars and vans is 55p for the first 10,000 business miles and 25p for every business mile after that. The UK tax year runs 6 April to 5 April, so your log should add up over that period rather than the calendar year.

Two conditions catch people out. If you have claimed capital allowances on the vehicle you cannot use the flat rate for it at all. And once you use flat rates for a vehicle you must keep using them for as long as that vehicle is in your business.

Keeping the records

The log is part of the records behind your return, so keep it with the rest of them rather than only on the phone. Download it when the tax year ends and file it with your accounts.

This is a log, not accounting software, and it is not tax advice. Take questions about your own vehicle — especially the capital allowances one — to your accountant.