How to keep a mileage log for Self Assessment

If you're self-employed and drive for work, you can claim your business miles at a flat rate per mile, instead of working out the real cost of running your car or van. HMRC calls this “simplified expenses”. Here's how the rates work for the two tax years people are dealing with right now, and what to write down.

The rates per business mile

GOV.UK's simplified expenses page for vehicles gives these flat rates:

The higher rate for cars and vans went up from 45p to 55p from 6 April 2026. If you're filling in your 2025 to 2026 return this January, use 45p for that year.

The flat rate replaces the actual costs of buying and running the vehicle, such as fuel, insurance, repairs and servicing. You claim one or the other, not both.

A worked example

Say you drove 12,000 business miles in your van between 6 April 2025 and 5 April 2026:

• 10,000 miles at 45p = £4,500
• 2,000 miles at 25p = £500
• Mileage claim for 2025 to 2026: £5,000

The same 12,000 miles in 2026 to 2027 would be 10,000 at 55p (£5,500) plus 2,000 at 25p (£500): £6,000.

Which year the 10,000 miles count over

If your accounts run with the tax year (6 April to 5 April), the 10,000 miles are the business miles you do in that tax year. HMRC's own guidance, the Business Income Manual at BIM75005, applies the threshold to the miles in an accounting period in its worked examples.

If your accounts run to a different date, such as 31 December, it's more involved. The manual says that “a business should use the mileage rates that apply to that tax year” when working out the profit for each tax year. Because the car and van rate changed on 6 April 2026, an accounting period that runs across that date has two different rates in it. If that's you, read BIM75005 or ask an accountant before you add up your claim.

A journey that crosses 10,000 miles

If one journey takes you past 10,000, split it: the miles up to 10,000 at the higher rate, the rest at 25p. For example, a 100-mile trip when you've already done 9,950 business miles is 50 miles at the higher rate and 50 miles at 25p.

Rules worth knowing before you start

From the same GOV.UK page, plus one from GOV.UK's travel expenses page:

• Once you use the flat rate for a vehicle, you keep using it for as long as you use that vehicle in your business.
• You can't use it for a vehicle you've already claimed capital allowances on, or included as an expense when working out your profits.
• Parking and other travel, such as train fares, can be claimed on top.
• Cars designed for commercial use, like black cabs or dual-control driving school cars, can't use the flat rate.
• Travel between home and work doesn't count. GOV.UK's travel expenses page lists it among the things you can't claim, along with non-business driving.

What to write down for each journey

GOV.UK says you must keep records of your business income and expenses, and that your records must be accurate and you must be able to identify business transactions. It doesn't set a format for a mileage log. One way to keep one is a line per journey with:

• the date;
• where you went from and to;
• why (the business reason);
• the business miles.

A running total shows when you pass 10,000 miles. Keep the log with your other records. GOV.UK says to keep records for at least 5 years after the 31 January deadline for that tax year: for a 2025 to 2026 return filed by 31 January 2027, that means until at least the end of January 2032.

Questions

Can I claim fuel as well as the mileage rate?

Not for the same vehicle. GOV.UK says the flat rate is instead of the actual costs of buying and running it, and gives fuel as one of those costs.

Does the 10,000 miles start again each year?

Yes. HMRC's worked examples in BIM75005 count it over each accounting period. If your accounts follow the tax year, that's each 6 April to 5 April. If they run to another date, see the section above on which year the miles count over.

I'm doing my 2025 to 2026 return now. Which rate do I use?

45p for the first 10,000 business miles, then 25p. The 55p rate applies from 6 April 2026, so it's for 2026 to 2027 onwards.

Sources

All checked on 19 October 2026:

• Simplified expenses if you're self-employed: vehicles (the rates per mile, and the rules above)
• Business records if you're self-employed and what records to keep
• How long to keep your records
• HMRC Business Income Manual, BIM75005 (which mileage rates apply when; updated 4 August 2026)
• Expenses if you're self-employed: travel (what you can't claim, including travel between home and work)

A free mileage log

Our free mileage log does the sums for you. It's for cars and vans (not motorcycles), and it assumes your accounts follow the tax year. You choose the tax year (2025 to 2026 or 2026 to 2027) on the Start sheet and write one journey per row. It keeps the running total, splits a journey that crosses 10,000 miles, and adds up your claim. It also flags journeys dated outside the tax year, or with no date or business reason. It's an Excel and Google Sheets file, with no sign-up and no email address.

This isn't tax advice, and the log isn't HMRC software. Check GOV.UK or an accountant for your situation.