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Guideby Gair

How to Track Business Miles for HMRC Self Assessment

If you're self-employed in the UK and you drive for work, your business miles are one of the largest deductions available to you. HMRC's Approved Mileage Allowance Payment (AMAP) lets you claim 45p per mile for the first 10,000 business miles, then 25p per mile after. For a mid-mileage sole trader doing 15,000 business miles a year, that's £5,750 off your taxable profit - worth £1,150 to £2,300 in real tax back depending on your tax band.

But - and this is the part most people miss - the deduction is only worth what you can prove. HMRC requires a contemporaneous mileage log, and getting it wrong can mean the deduction is disallowed retrospectively, with interest and penalties. This guide explains exactly what to record, how to record it, and where it goes on your Self Assessment.

What is a "business mile" for tax purposes?

A business mile is one driven wholly and exclusively for business. The clear-cut cases are easy:

  • Driving between two client sites in the same day
  • Going from your business base (which is not your home) to a customer
  • For gig drivers: from accepting a job to completing the drop-off
  • Driving to a supplier, training course, or business meeting

The harder cases:

  • Home-to-work commute: not claimable. HMRC treats this as ordinary commuting whether you're employed or self-employed.
  • First job of the day from home: generally not claimable if you have a fixed workplace. Is claimable if you have no fixed base (e.g. a roofer who starts at a different site every day).
  • Travel within a job: claimable - moving between rooms of a development site doesn't count, but driving from one site to another in the same day does.
  • Personal detour on a business trip: the personal portion is not claimable. Stopping at Tesco between two client visits means the Tesco-to-second-client miles need to be split.

See our full breakdown of what counts as business mileage for the edge cases.

The contemporaneous record rule

HMRC requires a record of each business journey made at or near the time of the trip. The key word is contemporaneous - written then, not later. The record must show:

  • The date
  • The start and end locations (postcodes or addresses)
  • The business purpose (which client, which delivery, which meeting)
  • The distance driven (in miles)

What HMRC explicitly does not accept:

  • Estimates. "About 200 miles a week" is not a record - it's a guess.
  • Reconstructions from memory. Writing it all down in January for the year just gone fails the contemporaneous test.
  • Maps Timeline data alone. Google Maps Timeline and Apple Maps history do record where you went, but neither distinguishes business from personal, neither shows business purpose, and neither is in a tax-acceptable format.

The AMAP rates for 2025/26 and 2026/27

  • Cars and vans: 45p per mile for the first 10,000 business miles per tax year, then 25p per mile
  • Motorbikes: 24p per mile (flat, no threshold)
  • Bicycles: 20p per mile (flat)
  • Passenger payment: additional 5p per mile per business passenger

The 10,000-mile threshold resets at the start of each UK tax year (6 April). It does not carry over.

Where mileage goes on your SA103

The mileage deduction is claimed on the SA103S (short) or SA103F (full) Self Assessment page for self-employed income. Specifically:

  • SA103S (turnover under £85k): Box 20 "Car, van and travel expenses" - put your total AMAP claim here. Tick the "I have used cash basis or simplified expenses" box.
  • SA103F (turnover over £85k): Box 21 of the equivalent section. Same logic - simplified expenses (AMAP) goes in the travel box.

You enter the total deduction, not the miles. So 15,000 business miles becomes £5,750 (10,000 × 45p + 5,000 × 25p) - that £5,750 is what you write on the form.

Practical record-keeping

You have three real options:

Option 1: Pen and paper

A small notebook in your glove compartment, filled in at the start and end of each business journey. Works if you're disciplined. Fails after about three weeks for most people.

Option 2: Spreadsheet

The most common approach and the worst one. Unless you fill it in in the car after every trip, it's not contemporaneous. Reconstructing a week's miles on Sunday from memory is exactly what HMRC's rule was written to exclude.

Option 3: A purpose-built mileage tracker app

The right answer for almost everyone. Background GPS captures the trip automatically as you drive, you tap once to classify it as business or personal, and the per-trip log + tax-year totals are ready when you need them. No discipline required - the app does the discipline for you.

For self-employed UK drivers, what to look for:

  • HMRC AMAP rates with the 10,000-mile threshold applied automatically
  • UK tax year (6 April to 5 April) baked in
  • Self Assessment-ready PDF with the per-trip detail HMRC requires
  • HMRC attestation cover sheet on the export
  • Offline-first GPS so you don't lose data in tunnels or rural areas
  • Free for the tracking - paying to record your own miles makes no sense

What to do when HMRC asks

If HMRC opens an enquiry on your return, they'll ask to see your mileage log. Three things matter:

  • Each business journey must be recorded individually
  • Each record must include the four fields (date, start, end, purpose, distance)
  • The record must have been made at or near the time of the journey

A purpose-built tracker handles all three structurally. A spreadsheet filled in weekly does not.

MileClear's approach

MileClear is a free UK mileage tracker built specifically for HMRC compliance. Every trip is GPS-recorded contemporaneously, classified business or personal with a tap (or auto-classified via saved locations or work schedule), and the AMAP calculation runs in real time as you drive. The Self Assessment PDF export (Pro, £4.99/mo) gives you per-trip detail + summary + attestation cover sheet - drop it onto your SA103 or hand it to your accountant. The tracking itself is free forever.

Install MileClear on the App Store.

The bottom line

Tracking business miles for HMRC is straightforward in concept and miserable in practice if you do it manually. The deduction is real and worth claiming - usually four-figure savings every year - but only if your records survive HMRC's contemporaneous-record test. Use a purpose-built tracker, classify trips in real time, and the SA103 line writes itself.