What Counts as Business Mileage? HMRC Rules with 8 Examples

Most mileage disputes are not about distance. The odometer is rarely in question; the reason for the journey is. Business mileage is defined by purpose, and purpose is the part of the record people forget to write down.

This guide sets out the test HMRC applies, walks eight everyday journeys through it, and covers the edge cases that quietly fail — the errand chained onto a client visit, the site that stopped being temporary, the second office.

The test HMRC applies

A journey qualifies as business travel in one of two ways:

1. Travel in the performance of your duties. The travel is itself part of the job — a delivery driver’s route, an engineer moving between call-outs, a surveyor driving to a site inspection.
2. Travel to a place you have to attend for work that is not a permanent workplace. Attending a client’s premises, a supplier, a training venue, or a temporary site.

And one category never qualifies:

Ordinary commuting. Travel between your home and a permanent workplace is a private expense, regardless of distance, hour, or how many detours the traffic forced.

The distinction that does the work here is permanent versus temporary workplace, and it is more technical than it looks. GOV.UK’s guidance on business mileage is the starting point; the detail sits in HMRC’s booklet 490 on travel expenses.

Eight journeys, sorted

#	The journey	Business mileage?	Why
1	Home → your usual office	No	Ordinary commuting, regardless of distance
2	Office → client site → office	Yes	Travel between workplaces during the working day
3	Home → client site, no office attendance	Yes	The client site is not a permanent workplace
4	Home → temporary site (under 24 months)	Yes	Temporary workplace, subject to the 24-month rule
5	Client site → second client site	Yes	Both ends are workplaces
6	Home → office, then office → supplier	Split	The first leg is commuting; the second is business
7	Office → home, via a personal errand	Split	The errand-to-home leg is private
8	Home → training course booked by employer	Yes	Attendance required for work at a non-permanent location

Rows 4 and 6 account for most of the mileage that gets removed on review, and both deserve unpacking.

The 24-month rule

A workplace is temporary until you expect to be there for more than 24 months and you spend, or expect to spend, more than 40% of your working time there. When both conditions hold, the workplace becomes permanent and journeys to it become ordinary commuting.

The rule bites on expectation, not on hindsight:

• A 30-month contract is permanent from day one, even though at month one you have only been there four weeks.
• An 18-month contract extended to 30 months stops qualifying from the date the expectation changed — not retroactively, and not at the 24-month mark.
• The 40% test matters too. A site you attend one day a week for three years can remain temporary, because you never cross the working-time threshold.

Because the test turns on what you expected and when, the contract or assignment letter is part of the mileage evidence. Keep it filed with the log.

The split day

The single most common overstatement is treating a whole day of driving as business because part of it was. Home to office is commuting. Office to supplier is business. Supplier to home is, in most cases, the return leg of the business journey rather than a commute — but only if you did not go back through the permanent workplace first.

Log the legs, not the day. A record that shows four legs with four purposes is far more defensible than one entry reading “Tuesday — client work, 84 miles”.

The journeys that quietly fail

The scenic detour. A route materially longer than the direct one needs a business reason for the extra distance. Traffic and closures are fine. A stop unrelated to work is not.

The weekend office visit. Going to your permanent workplace on a Saturday is still ordinary commuting. The day of the week does not change what the location is.

The “I was passing anyway” client call. A brief business stop on an otherwise private journey does not convert the whole journey. The business element is what is claimable.

The rate depends on cumulative mileage

Once a journey qualifies, the amount is set by the Approved Mileage Allowance Payments rates:

Business miles in the tax year	Cars and vans
First 10,000	45p per mile
Above 10,000	25p per mile

This is why per-journey logging is not enough on its own. The rate depends on your running annual total, so a log that records each journey but never accumulates the year-to-date figure invites the most common arithmetic error in UK mileage claims: applying 45p to every mile.

At 12,000 business miles the correct figure is £4,500 + £500 = £5,000. Applying 45p throughout gives £5,400 — a £400 overstatement, and one HMRC’s checks are built to spot because it is so frequent.

What the record has to show

Five fields per journey:

• Date — when the journey happened
• From and to — specific enough to identify the locations later
• Purpose — why, in a few words that would still make sense in three years
• Distance — the business miles for that journey

Plus the running annual total, so the 10,000-mile threshold is visible before you cross it rather than after.

“Client visit” is thin. “Site survey — Harper Ltd, Elm Street project” identifies the engagement and remains verifiable. The extra six words cost nothing at the time and are the difference between a record that stands and one that invites questions.

Getting the classification right without doing it by hand

The reason mileage logs decay is not that the rules are hard. It is that classification is a small task repeated several hundred times a year, and small repeated tasks lose to everything else on the calendar.

MileTrack detects journeys automatically and keeps business, commute, and private as separate types rather than one bucket. Saved places and repeated routes drive the suggestions, so a route you have already classified is proposed correctly the next time — and cumulative business mileage is tracked against the 10,000-mile threshold rather than left for you to total by hand.

Exports carry date, from, to, distance, purpose, and vehicle context in PDF, CSV, and XLSX, which are the fields this guide has been describing throughout.

Related guides

• Business Travel vs Commuting: HMRC Mileage Rules Explained
• HMRC Mileage Rates 2026: 45p and 25p AMAP Rates Explained
• HMRC Mileage Logbook Rules: Recordkeeping Checklist for 2026

Tax note: educational content only, not tax advice. Confirm your own circumstances with a qualified adviser before submitting a claim.