Where to Enter Mileage Allowance Relief on Self Assessment in the UK

Alan Bermingham

10 Years of Expertise in Fintech Innovation

6 min read

Pible / Blog

Updated: 14 Aug 2025

6 min read

Pible / Blog

Bookkeeping

Self-Assessment

Updated: 14 Aug 2025

Let’s Break This Down Together...

Missing out on mileage allowance relief because you’re not sure where it goes on your Self Assessment? You’re not alone, and it’s easier to sort than you might think.

In this guide, we’ll cover exactly what mileage allowance relief is, who’s eligible, and where to enter it on your tax return. You’ll also learn the HMRC rules, mileage rates, and the records you’ll need to keep.

By the end, you’ll know how to claim confidently and avoid common mistakes that could cost you money. Let’s dive in!

What is Mileage Allowance Relief?

Mileage allowance relief is a tax benefit for using your own vehicle for work journeys. If you are driving your vehicle for business purposes and your employer hasn’t fully reimbursed you at HMRC’s approved rates, you can claim relief. After considering any mileage allowance payments you have received from your employer, you may be able to claim tax relief on the difference if you were not fully reimbursed.

For cars and vans, the current approved rates are 45p per mile for the first 10,000 business miles. This drops to 25p per mile for any additional miles in the tax year.

Different rates apply for motorcycles (24p per mile) and bicycles (20p per mile). These rates are designed to cover the cost of driving for work, including fuel, repairs, maintenance, and vehicle ownership.

You can only claim for business journeys, not your regular commute. This distinction often catches people out when submitting their returns. You are only able to claim mileage allowance relief if the journey qualifies as business travel and you have not already been fully reimbursed by your employer.

Calculating Business Mileage

Calculating your business mileage is a crucial step in claiming mileage allowance relief on your tax return. Start by keeping a detailed mileage log or using a digital tracker to record every business trip you make throughout the tax year. For each journey, note the date, start and end locations, total miles driven, and the specific business purpose of the trip. This information forms the foundation of your mileage claim.

For cars and vans, you can claim 45p per mile for the first 10,000 business miles in a tax year, and 25p per mile for any additional miles over that threshold. If you use a motorcycle, the rate is 24p per mile, and for bicycles, it’s 20p per mile. Make sure to only include miles driven for business purposes, personal trips and commuting do not count.

Keep all supporting records, such as fuel receipts and maintenance invoices, as these may be needed to verify your claim. Accurate record-keeping ensures you can confidently claim the correct amount of mileage allowance relief and defend your claim if HMRC requests evidence.

HMRC Mileage Guidelines

HMRC sets out clear guidelines for claiming mileage allowance relief, ensuring that only legitimate business travel is included in your tax return. To claim mileage allowance relief, you must use your personal vehicle for business purposes and apply the approved mileage rates: 45p per mile for the first 10,000 miles in a tax year, and 25p per mile for any additional miles. For motorcycles and bicycles, the rates are 24p and 20p per mile, respectively.

Eligible business trips include travel to temporary workplaces, client meetings, and other journeys directly related to your work. You cannot claim for ordinary commuting or personal travel. HMRC requires you to keep accurate records of your business mileage, including a detailed mileage log with dates, destinations, and miles driven for each trip. These records must be kept up-to-date and retained in case HMRC requests to review them during an audit. Following HMRC’s mileage guidelines helps ensure your claim for mileage allowance relief is accurate, compliant, and fully supported if ever questioned.

Where to Enter Mileage Allowance Relief on Your Self Assessment

The location for entering your mileage claims depends on your employment status. Getting this right ensures you don’t miss out on tax relief you’re entitled to, and it is important to enter your mileage claims correctly on your tax returns to support your claim and comply with HMRC requirements.

If You're Employed

If you’re an employee, enter mileage claims in the “Employment” section of your Self Assessment tax return. Look specifically for the “Employment expenses” area.

You might need to claim mileage allowance relief if your employer only partially reimburses your business mileage, or does not reimburse you at all.

You’ll need to enter your total mileage claim in box 16 of the SA102 form. This is where HMRC expects to see all employment-related expense claims.

It’s helpful to include a brief note in the “Any other information” section. Explain that your claim relates to business mileage not fully reimbursed by your employer.

If You're Self-Employed

Self-employed individuals should enter mileage claims in the “Self Employment” section. This appears in a different part of the tax return from employment expenses.

If you use simplified expenses (the flat rate per mile method), enter your claim in box 12 of the SA103s form. This is the designated area for travel costs. For example, if you drove 10,000 business miles in the tax year, you can claim 45p per mile, which totals £4,500 (10,000 x 0.45 = £4,500).

For those using full expenses, include vehicle costs within the car and travel expenses section of the SA103f form. This method requires more detailed record-keeping.

Remember that self-employed people must choose either flat rate mileage or actual vehicle expenses. You cannot use both methods for the same vehicle in a tax year.

Documentation Needed to Support Your Claim

HMRC may ask for evidence to support your mileage claim. Keeping good records is essential for defending your claim if questioned.

Maintain a detailed log of all business journeys, including dates and locations. Note the purpose of each trip and the total miles travelled for each journey.

It's helpful to record odometer readings at the start and end of each journey. This provides concrete evidence of the distance travelled for business purposes.

Keep all records for at least five years after the 31 January submission deadline. HMRC can investigate claims going back several tax years if they have concerns.

Common Mistakes to Avoid

A frequent error is claiming for regular commuting between home and your permanent workplace. HMRC does not allow tax relief for these journeys.

Another mistake is failing to subtract amounts already paid by your employer. You can only claim the difference between what you received and the HMRC approved rate.

Using incorrect mileage rates is also common. Double-check you're applying the right rate for your vehicle type and total annual business mileage.

Self-employed people using the flat rate method cannot claim separate vehicle expenses. Insurance, repairs and other costs are already factored into the mileage rate.

Final Thoughts

Correctly entering your mileage allowance relief can save significant money on your tax bill. The potential savings make it worth taking time to get this right.

Remember that employed people use the Employment section, while self-employed individuals use the Self Employment section. Those with mixed status must split claims accordingly.

Always keep detailed mileage records to back up your claims. Good documentation is your best defence if HMRC questions your mileage allowance relief.

Simplifying Mileage Allowance Relief Claims

Getting your mileage claims right shouldn't be a headache when filing your Self Assessment. Pie places your mileage relief in exactly the right section of your return automatically.

Our app features real-time tax calculations that update as you add journeys. You'll instantly see how each business trip affects your overall tax position.

Feel free to explore the Pie app if you'd like to see how we can make your next Self Assessment simpler and more accurate.