The example in the calculator
You use your own car for 4,000 business miles in 2026/27 and your employer pays nothing towards it.
- Approved amount: 4,000 × 55p = £2,200.
- Paid by employer: £0.
- Relief you can claim: £2,200 — under £2,500, so you can use the simple online claim or form P87.
- Tax back: £2,200 × 20% = £440 (£880 if you pay 40%).
Relief is not cash for the full amount — it reduces the income you are taxed on. HMRC either sends a refund or adjusts your tax code.
Step by step
- Gather your mileage. Add up business miles for the tax year (6 April to 5 April). A notebook or a phone app is fine.
- Check what you were paid. Payslips or your expenses system show any mileage payments.
- Use the calculator above to get the relief figure.
- Claim:
- £2,500 or less: HMRC’s online “Claim tax relief for your job expenses” service, or form P87 by post.
- Over £2,500, or if you already do Self Assessment: put it on your tax return.
- Keep records for at least 22 months after the end of the tax year (longer if you file Self Assessment).
Which form when?
| Your situation | How to claim |
|---|---|
| Total expenses £2,500 or less, no Self Assessment | Online claim or P87 |
| Total expenses over £2,500 | Self Assessment tax return |
| Already file Self Assessment | On your tax return |
| Self-employed | Not MAR — use simplified expenses (also 55p/25p) on your return |
Relief at a glance (employer pays nothing)
| Business miles | Relief | Back at 20% | Back at 40% |
|---|---|---|---|
| 1,000 | £550 | £110 | £220 |
| 2,000 | £1,100 | £220 | £440 |
| 4,000 | £2,200 | £440 | £880 |
| 4,545 | £2,500 | £500 | £1,000 |
| 8,000 | £4,400 | £880 | £1,760 |
4,545 miles is roughly where a claim reaches the £2,500 limit for the simple online route.
Going back in time
You can claim for up to four previous tax years. For years before 2026/27 the car rate was 45p a mile for the first 10,000 miles, so use 45p for those years.
What if my employer pays something, but not much?
Enter what they pay per mile in the “Employer pays” box. The calculator subtracts it from the 55p approved amount and shows the relief on the difference. For example, at 25p a mile on 4,000 miles your employer pays £1,000, so you claim relief on £1,200 — worth £240 at 20%. The same online claim or P87 route applies.
FAQ
How much tax relief can I claim for 4,000 business miles?
If your employer pays nothing, £2,200 of relief (4,000 × 55p), which is £440 back at 20% or £880 at 40%.
When do I need Self Assessment instead of a P87?
When your total expenses claim is over £2,500, or if you already file a tax return.
Can I claim for my commute?
No. Only business journeys count — not ordinary travel between home and your permanent workplace.
Sources: GOV.UK “Travel – mileage and fuel rates and allowances” (55p rate, updated 21 May 2026); ATT news 21 May 2026 (written statement HCWS62, backdated to 6 April 2026); GOV.UK “Advisory fuel rates” (rates from 1 September 2026, updated 21 August 2026); Ross Martin Tax Consultancy. Checked 5 November 2026.