Mileage Allowance Relief Calculator UK
Estimate your UK mileage allowance tax relief based on HMRC approved mileage rates, employer reimbursement, and your income tax band.
Complete Guide to the Mileage Allowance Relief Calculator UK
If you use your own vehicle for business travel in the UK, there is a strong chance you could be entitled to tax relief. Many employees receive less than the HMRC approved mileage rate from their employer, and the gap between what was paid and what HMRC allows can be claimed as mileage allowance relief. This calculator is designed to give you a practical estimate in minutes, so you can understand what you may be able to claim and how much tax that claim could save you.
The key point is simple: you do not claim back the full mileage shortfall as cash. Instead, you claim tax relief on that shortfall. So if your allowable shortfall is £1,000 and you pay tax at 20%, your estimated tax saving is £200. If you pay at 40%, the same shortfall could reduce your tax by around £400. That is why your tax band matters in every mileage relief calculation.
What mileage allowance relief means in practice
Mileage allowance relief usually applies to employees who:
- Use their own car, van, motorcycle, or bicycle for qualifying business journeys.
- Receive no mileage payment or receive less than HMRC approved mileage rates from their employer.
- Pay income tax and want to claim relief on business travel costs not fully reimbursed.
Typical examples include driving to temporary sites, client meetings, training venues, or between workplaces. Your regular home-to-permanent-office commute is normally not eligible. Keeping this distinction clear is one of the most important steps in getting your claim right.
Official HMRC mileage rates used by most employee claims
The calculator uses the commonly applied Approved Mileage Allowance Payments framework. These rates are central to the UK mileage allowance relief system for employees using personal vehicles for business travel.
| Vehicle type | Approved mileage rate | Key threshold | Extra passenger rate |
|---|---|---|---|
| Car or Van | 45p per mile, then 25p | 45p for first 10,000 business miles, 25p above 10,000 | 5p per qualifying passenger mile |
| Motorcycle | 24p per mile | No 10,000 mile step rate | Not typically added in the same way |
| Bicycle | 20p per mile | No 10,000 mile step rate | Not applicable |
These figures are widely referenced by HMRC guidance for employee mileage allowances. For authoritative details, check:
- HMRC rules for business travel and mileage on GOV.UK
- Tax relief for employees using their own vehicle for work
- Current UK income tax rates and bands
How the calculator works
- Enter your vehicle type because each vehicle category has a different approved mileage rate.
- Enter your total business miles for the tax year. Accuracy here matters more than almost any other input.
- Add employer reimbursement either as pence per mile or as an annual total in pounds.
- Add qualifying passenger miles if you used a car or van and carried eligible colleagues for business journeys.
- Select your tax band to estimate the actual tax reduction on the mileage shortfall.
The result panel then displays:
- HMRC approved mileage amount.
- What your employer paid you.
- Your unreimbursed shortfall (if any).
- Your estimated tax relief based on your tax band.
Understanding the numbers: relief vs reimbursement
Many people assume that if HMRC allows £3,000 and their employer paid £2,000, HMRC pays them £1,000. That is not normally how this works for employees. In most cases, HMRC allows you to claim tax relief on the £1,000 difference. So your real cash impact is linked to your tax rate:
- 20% tax band: £1,000 shortfall may mean around £200 tax relief.
- 40% tax band: £1,000 shortfall may mean around £400 tax relief.
- 45% tax band: £1,000 shortfall may mean around £450 tax relief.
This distinction helps you set realistic expectations before submitting any claim.
Comparison table: estimated tax relief by tax band
The table below shows how the same unreimbursed mileage amount leads to different relief values depending on income tax rate.
| Unreimbursed allowable mileage amount | Estimated relief at 20% | Estimated relief at 40% | Estimated relief at 45% |
|---|---|---|---|
| £500 | £100 | £200 | £225 |
| £1,500 | £300 | £600 | £675 |
| £3,000 | £600 | £1,200 | £1,350 |
Worked example for a UK employee
Suppose you drove 12,000 business miles in your own car and your employer paid 30p per mile. You are a higher rate taxpayer at 40%.
- HMRC approved amount:
- First 10,000 miles at 45p = £4,500
- Next 2,000 miles at 25p = £500
- Total approved = £5,000
- Employer paid amount:
- 12,000 miles at 30p = £3,600
- Unreimbursed allowable shortfall:
- £5,000 minus £3,600 = £1,400
- Estimated tax relief:
- £1,400 at 40% = £560
This example is exactly why a mileage allowance relief calculator is useful. It translates rates and thresholds into a clear estimate you can use when preparing your claim.
Common mistakes that reduce or delay claims
- Including normal commuting miles: usually ineligible for this type of relief.
- Relying on rough estimates: poor records can lead to under-claiming or challenge.
- Ignoring the 10,000 mile threshold for cars and vans: over 10,000 miles has a lower approved rate.
- Confusing reimbursement with relief: you claim tax relief on the shortfall, not usually the full shortfall as a payment.
- Forgetting passenger allowance where eligible: 5p per qualifying passenger mile can add up over a year.
What records you should keep
Strong record keeping is essential. A reliable mileage log should include:
- Date of each journey.
- Start point and destination.
- Business purpose of the trip.
- Mileage for the journey.
- Any qualifying passenger details where relevant.
You should also keep payslips, expense reports, and employer mileage statements so you can prove how much reimbursement you actually received. Clear records make it easier to validate your numbers if you need to explain them later.
How to submit a claim in the UK
Depending on your circumstances, employees often claim through a P87 route or via Self Assessment. The right route can depend on your total claim size and whether you already complete a tax return. HMRC guidance on GOV.UK explains the available claim methods and supporting information needed.
Claims can sometimes be made for previous tax years, subject to HMRC time limits. If you believe you under-claimed before, review your mileage logs and employer payments year by year, then estimate each year separately rather than blending all years into one total.
Who this calculator is best for
This mileage allowance relief calculator UK is most useful for employees who regularly drive for work and receive no mileage payment or a reduced mileage payment from their employer. It is also useful for workers who want a quick estimate before deciding whether to submit a formal claim.
If your tax affairs are complex, or if part of your travel falls under different expense rules, you may need tailored tax advice. The calculator provides a robust estimate, but it is not a legal or personal tax ruling. Always compare your final figures with up to date HMRC guidance before submitting.
Practical tips to maximise claim accuracy
- Log business mileage weekly, not months later.
- Separate business and personal mileage at source.
- Track reimbursements from payroll and expenses systems together.
- Check your highest tax band for the period claimed.
- Retain evidence for each tax year in a dedicated folder.
Final thought
Mileage allowance relief is one of the most overlooked employee tax claims in the UK. A structured calculator turns a confusing ruleset into clear numbers: approved amount, employer payment, shortfall, and likely tax relief. If your employer pays below HMRC approved rates, even a moderate annual business mileage total can produce a meaningful tax saving. Use the calculator above, keep excellent records, and verify your claim route through official GOV.UK guidance before submission.