How to Calculate Business Mileage in the UK

Step 1 — Identify which journeys count

Only business journeys qualify — travel you make for your work that is not ordinary commuting. The main qualifying categories are:

• Travelling to a customer, client or patient
• Travelling between different work sites
• Making a detour to a business appointment on the way to or from your normal workplace
• Travelling to a temporary workplace (expected to last less than 24 months)

Step 2 — Record the distance

Use the shortest reasonable road route. Postcode-to-postcode road routing gives a defensible, repeatable distance. Avoid rounding or estimating from memory — HMRC can ask for evidence.

Step 3 — Apply the correct rate

In 2026/27, multiply the first 10,000 qualifying miles by 55p and any miles above 10,000 by 25p. Keep a running total so you know when you cross the threshold.

Worked example

At 54 miles a week, you would reach the 10,000-mile threshold in roughly 37 weeks. Miles driven after that are worth 25p each.