CIS Tax · Mileage · 2025/26 and 2026/27
Mileage is the biggest single expense on most CIS returns, and the one people get wrong most often: the wrong rate for the year, the wrong travel rule, or no log to back it up. Here is how to get all three right.
By QuoteDone Editorial Team · Last updated: 25 September 2026 · Checked against GOV.UK and HMRC manuals
Every business mile you log and claim lowers your taxable profit. For a subcontractor with profit between £12,570 and £50,270, each £1 of expenses saves 26p (20p Income Tax plus 6p Class 4 National Insurance). At 55p a mile, that is 14.3p of tax saved per business mile; at 45p, it is 11.7p.
The catch is that the rate changed in April 2026, and the rules on which journeys count are different for the self-employed than most guides suggest.
The Mileage Rates: Which One for Which Return
| Cars and vans (simplified expenses) | 2025/26 return (due 31 January 2027) | 2026/27 onwards |
|---|---|---|
| First 10,000 business miles in the tax year | 45p per mile | 55p per mile |
| Each business mile above 10,000 | 25p per mile | 25p per mile |
| Motorcycles | 24p per mile | 24p per mile |
The flat rate covers fuel, insurance, servicing, repairs and other running costs. You can add parking and tolls for business journeys on top. There is no passenger supplement for the self-employed. Source: GOV.UK – Simplified expenses: vehicles.
What are your miles worth?
Add your mileage to your expenses and see how it changes your CIS refund.
CHECK YOUR REFUND NOW →✓ No registration required · 100% Free · HMRC 2026/27 Aligned
Which Journeys Count for a Self-Employed Subcontractor
For sole traders, travel is allowable if it is wholly and exclusively for the business. HMRC's business income manual, following the 1971 case Horton v Young (a bricklayer working on different sites), sets out how that applies to subcontractors:
| Journey | Usually claimable? | Why |
|---|---|---|
| Home to site, when you work at two or more sites in the year | ✓ Normally yes | HMRC's guidance says this travel should normally be allowed |
| Between sites during the working day | ✓ Yes | Travel within the business |
| Site or home to a supplier or merchant for job materials | ✓ Yes | Wholly for the business |
| Home to the one site you work at all year, or one of a very few | ⚠ Possibly not | That site may count as your business base, making the journey a commute |
| Home to your own permanent yard, unit or office | ✗ No | Travel from home to your place of business is not allowable |
| Personal trips during the day | ✗ No | Not for the business |
Sources: HMRC – BIM37675 Sub-contractors and BIM37620 Travel to and between sites.
Worked Example: What the Right Rate Is Worth
A subcontractor drives 12,000 business miles in a year, with profit between £12,570 and £50,270, so each £1 of expenses saves 26p.
12,000 business miles, 2025/26 vs 2026/27
Using 55p on the 2025/26 return would overstate expenses by £1,000. HMRC can correct that and charge a penalty for a careless error.
Mileage Rate or Actual Van Costs?
You can claim the flat rate or the actual costs of running the vehicle (fuel, insurance, repairs, servicing, road tax, the business share of each). The choice matters because of three GOV.UK rules:
- Once you use the flat rate for a vehicle, you must keep using it for as long as you use that vehicle in your business.
- You cannot use the flat rate for a vehicle you have already claimed capital allowances on, or included as an expense when working out your profit.
- Under cash basis, the standard method for sole traders, the cost of a van you buy is an allowable expense, and claiming it rules out the flat rate for that van.
Existing van, 2026/27: 15,000 total miles, 12,000 business (80%)
The running costs are illustrative. With a new, expensive van, or in the year you buy one, actual costs can win. Run your own figures through HMRC's simplified expenses checker before you choose, because the flat-rate choice is permanent for that van.
Keep a Mileage Log HMRC Will Accept
- Record every business journey as it happens: date, start point, destination, purpose and miles. Paper or a phone app both work, as long as it is dated and complete.
- Note the odometer reading at the start of each tax year (6 April) so you can show total miles and your business percentage.
- Keep evidence that you were on site: job sheets, site sign-in records, invoices, material delivery notes.
- Keep business and private journeys apart. A school run or supermarket stop is not a business mile.
- Missed some entries? Rebuild them from real records such as job sheets, invoices and diaries. Do not guess or round up.
- Keep the log for at least 5 years after the 31 January deadline. For 2025/26, that is until at least 31 January 2032.
Frequently Asked Questions
What is the mileage rate for CIS subcontractors?
For cars and vans under simplified expenses, the rate is 45p per mile for the first 10,000 business miles in the 2025/26 tax year and 55p per mile from 6 April 2026 for 2026/27. Business miles above 10,000 in a tax year are 25p in both years.
Can I claim mileage from home to site?
Usually, if you work at two or more sites a year. HMRC's guidance says that where a subcontractor works at two or more different sites during a year, travel between home and those sites should normally be allowed. If you work at one site, or a very small number, that site may be treated as your business base, and travel from home to it is then not allowable.
Does the 24-month rule apply to self-employed subcontractors?
The 24-month temporary workplace rule is part of the tax rules for employees. For self-employed subcontractors, HMRC's business income guidance uses a different test, based on where your business is really based and how many sites you work at, following the Horton v Young case.
Can I claim fuel as well as mileage?
No. The flat rate covers fuel, insurance, servicing, repairs and the other costs of running the vehicle. You can add parking and tolls for business journeys on top, and other travel such as train fares.
Can I claim 5p per mile for a passenger?
No. The simplified expenses flat rates for the self-employed do not include a passenger supplement. The 5p per passenger figure belongs to the mileage allowance rules for employees.
Should I use mileage rates or actual van costs?
It depends on your vehicle's costs and your business miles. The flat rate is simpler and often better for older or cheaper-to-run vans, while actual costs can be higher for expensive vehicles. Once you use the flat rate for a vehicle, you must keep using it for as long as you use that vehicle in your business.
What records do I need for a mileage claim?
Keep a dated record of each business journey: date, start and end point, purpose and miles. Keep supporting evidence such as job sheets, site sign-in records or invoices. Keep your records for at least 5 years after the 31 January deadline for the tax year.
Important: This article is general information about mileage and travel expenses for self-employed subcontractors, not personal tax advice. Whether a journey is allowable depends on the facts of your work pattern. Always verify against GOV.UK or speak to a qualified accountant.
Author: QuoteDone Editorial Team · Last updated: 25 September 2026
Sources: GOV.UK – Simplified expenses: vehicles · GOV.UK – Travel expenses · GOV.UK – Cash basis · HMRC – BIM37675 · HMRC – BIM37620
Ready to claim your CIS refund?
Use our free calculator to find out what HMRC owes you.
CHECK YOUR REFUND NOW →Need professional invoices fast?
Create clean, compliant invoices in seconds with our free tool.
TRY FREE INVOICE GENERATOR →