What HMRC needs in a business mileage log
If you claim mileage for business journeys, the figure has to come from somewhere. HMRC's guidance on GOV.UK says what you should record and how long to keep it – and the answer depends a little on whether you are an employee or self-employed. This guide brings the official pages together in one place.
Updated October 2026
Why you need a mileage log at all
Most mileage claims in the UK are worked out per business mile: the approved mileage rates for employees, and the flat rates in simplified expenses for the self-employed. Both are multiplied by your business miles, so the miles are the number HMRC may ask you to back up. A log is the record that shows which journeys were business and how far you drove.
Employees using their own car
GOV.UK's page Claim tax relief for your job expenses: vehicles you use for work tells employees who use their own vehicle to:
- keep records of the dates and mileage of their work journeys,
- add up the business miles for each type of vehicle used for work, and
- take off any mileage allowance the employer paid.
The same page says that if you send copies of your mileage logs with a claim, they must give the reason for every journey and the start and end postcodes. If you claim for more than one job, you need a separate log for each employment.
So, for every business journey, a log that covers what GOV.UK asks for contains:
- the date,
- where the journey started and ended (with postcodes),
- the reason for the journey, and
- the business miles.
Regular travel between home and your normal workplace does not count. GOV.UK says the relief does not include travelling to and from your work, unless it is a temporary place of work. Our guide Commuting vs business mileage explains where that line falls.
If you have a company car
With a company car you do not use the approved mileage rates. GOV.UK says you can claim relief on the fuel or electricity you paid for on business trips, and that you need records showing the actual cost. If your employer pays some of it back, you can only claim the difference. A mileage log still matters here: it shows which journeys were business.
The self-employed
If you use simplified expenses, you claim a flat rate per business mile instead of the actual cost of buying and running the vehicle. GOV.UK's instruction is short: keep records of your business miles for vehicles. The vehicles page gives the flat rates, and adds that you can claim other travel costs, such as parking, on top.
Under travel expenses for the self-employed, GOV.UK lists travel between home and work and non-business driving as costs you cannot claim. In practice, a log with the same fields as above – date, start and end, reason and miles – is a sensible way to show which miles were business.
How long to keep the records
| Who | How long, according to GOV.UK |
|---|---|
| Self-employed | At least 5 years after the 31 January submission deadline of the tax year |
| Self Assessment, not self-employed | At least 22 months after the end of the tax year the return is for |
| Employers (PAYE records, including taxable expenses and benefits) | 3 years from the end of the tax year they relate to |
GOV.UK's example for the self-employed: for a 2022 to 2023 return sent online by 31 January 2024, keep the records until at least the end of January 2029. Different periods apply if a return is sent late – see the sources below.
Tips for a log that holds up
- Write it as you go. Reconstructing a year of journeys from memory is where gaps and guesses creep in.
- Record private trips too, or at least the odometer. Totals that add up to what the car actually drove make the business miles easier to explain.
- Be specific about the reason. “Site visit, 14 Mill Lane, client Smith & Co” says more than “work”.
- Count per tax year. The approved rates change after 10,000 business miles in a tax year, and the UK tax year runs from 6 April to 5 April.
Frequently asked questions
Does HMRC have an official mileage log form?
The GOV.UK pages list what to record – dates, mileage, the reason for each journey and the start and end postcodes – not a particular form, spreadsheet or app.
Can I keep my mileage log on my phone?
GOV.UK asks for the information, not for paper. What matters is that the log contains the details listed above and that you can send copies when you claim.
Do I need to log my commute?
Ordinary commuting is not business mileage, so it is not part of a claim. Logging it as private still helps the totals add up to the miles the car drove.
How Körlogg helps
Körlogg is an iPhone app that keeps the log for you. It records each trip with GPS as you drive – date, start and end time, start and end address, and the distance in miles – and you swipe to mark it business or private and add the reason. With work hours switched on, trips between your saved home and workplace are marked private, as ordinary commuting. Odometer readings at the start and end of each trip are filled in from one reading you enter (calculated values are marked ≈), and cars carry UK registration plates. With Körlogg Pro you export the log as PDF or Excel and see the approved amount at HMRC's rates, counted per tax year from 6 April. Changes made afterwards are listed in the export. Körlogg has no affiliation with HMRC, and HMRC decides whether a claim is accepted. Körlogg on the App Store
Sources
- Claim tax relief for your job expenses: vehicles you use for work – GOV.UK
- Simplified expenses if you're self-employed – GOV.UK
- Simplified expenses: vehicles – GOV.UK
- Expenses if you're self-employed: travel – GOV.UK
- Business records if you're self-employed: how long to keep your records – GOV.UK
- Keeping your pay and tax records: how long to keep your records – GOV.UK
- PAYE for employers: keeping records – GOV.UK
Checked against the sources on 14 October 2026. This guide is general information, not tax advice. Rules can change – check GOV.UK or ask an accountant about your own case.