Business Mileage Log: How to Keep Records That Work

A business mileage log is a running record of every business journey you make: the date, where you went, why, and how many miles. If you are self-employed and claim vehicle costs using HMRC's flat rate per mile, the log is the evidence for the whole claim, so it needs to be kept as you go. This guide explains what to record, how the flat rates work, and how to keep a log that holds up if HMRC asks to see it.

Key takeaways

• Record date, start and end place, purpose and miles for each trip.
• The flat rate for cars and vans rose to 55p per mile for the first 10,000 business miles from 6 April 2026. It was 45p before that.
• The flat rate replaces fuel, insurance, repairs and servicing. Parking is claimed on top.
• Travel between home and work is not business mileage.
• Keep the log for at least 5 years after the 31 January deadline.

What is a business mileage log?

It is a list of business journeys with enough detail for someone else to see that each one happened and was for work. It can be a notebook kept in the vehicle, a spreadsheet or an app. HMRC does not prescribe a format. What matters is that it is accurate, complete and written at the time.

You need one whichever way you claim. On the flat rate, miles multiplied by the rate is the claim. On actual costs, the log shows what share of your driving was for business.

How the flat rate works

Sole traders, and partnerships with no company as a partner, can use simplified expenses. For vehicles, that means a flat rate per business mile instead of the actual costs of buying and running the vehicle. GOV.UK currently shows these rates:

• Cars and goods vehicles, first 10,000 business miles: 55p per mile for the 2026/27 tax year, and 45p per mile before 6 April 2026.
• Cars and goods vehicles, after 10,000 miles: 25p per mile.
• Motorcycles: 24p per mile.

The change of rate matters this winter. The 2025/26 tax return, due online by 31 January 2027, uses 45p. Journeys since 6 April 2026 use 55p. Keep the two tax years separate in your log.

The conditions on GOV.UK are short but strict:

• You cannot use the flat rate for a vehicle you have already claimed capital allowances for, or included as an expense when working out your profits.
• Once you use the flat rate for a vehicle, you must continue to do so for as long as you use that vehicle for your business.
• You do not have to use flat rates for all your vehicles.
• Cars designed for commercial use, such as black cabs and dual control driving instructors' cars, cannot use simplified expenses.

What you can and cannot claim on top

The flat rate stands in for the costs of buying and running the vehicle. GOV.UK gives insurance, repairs, servicing and fuel as examples, so none of those can be claimed again. It also says you can claim all other travel expenses, such as train journeys, and parking on top. HMRC's Business Income Manual adds that the rate does not include tolls, congestion charges and parking fees for a particular journey, which are allowable where incurred solely for business. Fines and penalty charges are never allowable. For the wider picture, see our guide to sole trader allowable expenses.

What counts as a business journey?

A business journey is one made for the purposes of your trade: visiting a customer, collecting stock, going to a temporary site, taking takings to the bank. GOV.UK's list of car, van and travel expenses says you cannot claim for non-business driving or for travel between home and work. So the daily trip from home to your own shop, unit or regular workplace is commuting, not business mileage.

Flat rate mileage and actual costs compared

Neither method is better for everyone. GOV.UK has a simplified expenses checker for comparing them. Drivers who work through apps should read our comparison of mileage vs actual costs for Uber drivers.

Step by step: setting up a log that works

1. Pick one method and stick to it. A notebook, spreadsheet or app all work. Mixing them leaves gaps.
2. Note the odometer reading on 6 April and again on 5 April the following year. A dated photo of the dashboard is enough.
3. Record each business journey on the day: date, start place, end place, purpose and miles.
4. Make the purpose specific. "Quote for kitchen, Mrs Hall, Croydon" is evidence. "Work" is not.
5. Leave out commuting and private trips.
6. Keep receipts for parking, tolls and congestion charges with the log.
7. Total the miles monthly as part of your month-end bookkeeping, and keep a running total so you know when you pass 10,000.
8. Back it up and keep it. GOV.UK's guide to business records if you're self-employed says records must be kept for at least 5 years after the 31 January submission deadline.

Worked example (illustrative)

"Priya", an illustrative example, is a self-employed mobile dog groomer who uses her own car and claims the flat rate. Her log for the 2025/26 tax year shows 12,000 business miles. The claim for that year is:

• 10,000 miles x 45p = £4,500
• 2,000 miles x 25p = £500
• Total = £5,000

She also has receipts for £180 of parking at customer visits, which she claims on top. She does not claim fuel, insurance or her MOT and service, because the flat rate already covers running the car.

If she drives the same 12,000 business miles in 2026/27, the first 10,000 are at 55p: 10,000 x 55p = £5,500, plus 2,000 x 25p = £500, a total of £6,000.

Priya and these figures are invented for illustration and are not a real client.

Employees and company directors

Simplified expenses cannot be used by limited companies. If you are an employee or a director using your own car for company business, a separate regime applies, with its own rates and paperwork. The record keeping habit is the same, but the rules are not. See director mileage: company car vs own car.

Common mistakes

• Rebuilding the log in January. A log written at the time is far stronger.
• Claiming fuel as well as the flat rate. That counts the same cost twice.
• Logging the commute. Home to a regular workplace is not business travel.
• Using one rate across two tax years. Apply 45p up to 5 April 2026 and 55p from 6 April 2026 for the first 10,000 miles of each year.
• Switching to the flat rate after claiming the car's cost. Not allowed for that vehicle.
• No odometer readings. Without them there is nothing to test the log against.

How we can help

We set clients up with a simple mileage log, review it each month alongside the rest of the books, and work the claim into the tax return under the method that applies to the vehicle. Bookkeeping starts from £150 per month on a fixed fee. See our bookkeeping service, view our pricing, or contact us before the 31 January 2027 deadline.