Travel Claims · 2026/27
The 24-Month Rule: When Your Site Stops Being a Tax Deduction
You have been travelling 45 miles to the same site for 18 months and claiming the mileage. The job gets extended. At that exact moment — before you have been there 24 months — HMRC considers the site permanent and your travel claims stop. Here is what you need to know.
Travel to and from a construction site is one of the largest expense claims a subcontractor makes. For most workers, it is entirely legitimate — right up until the moment HMRC decides the site is no longer temporary. When that happens, the claims stop. And if HMRC decides the site became permanent months or years ago, the tax relief already claimed can be reclaimed with interest.
The Two Tests HMRC Uses — and Why Both Matter
Travel to a workplace is tax-deductible only when that workplace is "temporary." HMRC's definition of temporary is more specific — and more dangerous — than most subcontractors realise. There are two tests, and a site must pass both to remain temporary.
Both tests must be passed simultaneously. A site that fails either test — regardless of the other — is treated as a permanent workplace, and travel claims cease.
The rule does not wait for you to reach 24 months. The moment you expect to reach 24 months — the moment you sign that extension — the clock resets to zero and your claims stop.
CIS Tax Insights, 2026The Expectation Test: The Most Dangerous Part of the Rule
It is not about how long you have been there. It is about how long you expect to be there.
The 24-month rule is triggered by expectation, not by actual duration. The moment you sign a contract extension that takes your expected total time beyond 24 months — even if you are only 14 months in — the site ceases to be temporary from that signing date. Not from month 24. From the date your expectation changed. This is the detail that catches subcontractors who have been claiming legitimately for over a year and assume they have time before the rule applies.
If HMRC determines that your expectation changed at a date earlier than you claimed, they can disallow all travel claims from that earlier date and demand repayment of the associated tax relief — plus interest from the date the liability arose. A 14-month period of legitimate-looking £40/day mileage claims can become a £2,500+ unexpected bill.
What This Looks Like in Practice
This is the scenario that plays out regularly — a long-running project, a contractor who keeps renewing, and a subcontractor who does not realise the moment the rule was triggered.
| Daily mileage claim (90 miles × 45p) | £40.50/day |
| Annual mileage claim (220 days) | £8,910 |
| Tax saved at basic rate (20%) | £1,782/year |
| If site reclassified as permanent 14 months in — claims disallowed | −£10,395 |
| Tax to repay at basic rate (20%) | −£2,079 |
| Interest on overdue tax (HMRC rate) | Additional |
| Total unexpected liability — basic rate taxpayer | £2,079+ |
Practical Checklist: Protecting Your Travel Claims
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Track the Expected End Date for Every Site — From Day One Keep a simple record — a spreadsheet is sufficient — of every site you work at, the start date, the current expected end date, and the 24-month threshold date. Update it every time a contract is extended. The moment an extension is signed, recalculate whether the total expected duration now exceeds 24 months.
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Review Every Site at the 18-Month Mark Set a calendar reminder at 18 months for every ongoing site engagement. At that point, honestly assess whether the contract is likely to be extended beyond 24 months total. If there is any reasonable expectation that it will, assume the worst and stop claiming travel. It is significantly easier to resume claims if you were wrong than to repay claims if HMRC decides you were right.
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Stop Claiming the Moment Expectation Changes — Not at Month 24 This is the single most important action. When you sign an extension that takes your expected total beyond 24 months, stop claiming travel from that date. Keep a written note of when you stopped and why. HMRC may ask for this documentation in a compliance check, and a contemporaneous record is far more convincing than a reconstruction.
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Monitor the 40% Time Rule Separately Even on short-duration contracts, if you are spending more than 40% of your total working time at one location, the site can become permanent. If you work full-time on a single site — even a 12-month contract — you may be breaching the 40% threshold. Log your working days at each site to demonstrate you remain under the threshold if HMRC queries it.
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Understand That a New Site Nearby Does Not Automatically Reset the Clock Some subcontractors move to a different building or phase on the same development and assume the 24-month clock resets. It often does not. HMRC looks at whether the new location is substantially different or whether it is effectively the same workplace under a different name. A new site must be genuinely separate in location and nature to restart the clock.
Is Your Site Temporary or Permanent? The Quick Test
- Expected total duration at this site is under 24 months
- You spend less than 40% of your total working time there
- No extension has been signed that would take you over 24 months
- The site is genuinely separate from any previous nearby engagement
- You are monitoring the position and have a record of doing so
- You expect — or have signed a contract — to be there for 24 months or more in total
- You spend more than 40% of your total working time at this location
- An extension has been signed taking the total expected duration over 24 months
- The "new site" is effectively the same location under a different phase name
Review Your Current Sites This Week
The 24-month rule is not complicated, but it requires active monitoring. The subcontractors who get caught by it are not the ones who misunderstood the rule — they are the ones who understood it perfectly and then forgot to check when their contractor sent over the extension paperwork.
Look at every site you are currently working on. Note when you started, what the current expected end date is, and when the 24-month threshold falls. For any site you have been on for more than 12 months, ask yourself honestly whether a further extension beyond 24 months is likely — and if so, whether you have already mentally crossed that threshold even without signing anything formally.
Document your decision today. A written note — "I reviewed this site on [date], expected duration is [x], claims remain valid / I have stopped claiming from [date]" — costs nothing and is your first line of defence if HMRC ever asks.
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This article is for informational purposes only and does not constitute professional tax advice. The 24-month rule involves specific facts and individual circumstances — always confirm your position with a qualified accountant. Based on 2026/27 HMRC guidance.