55p Mileage Allowance: What to Do When HMRC Questions Your Claim

If HMRC questions your 55p mileage allowance claim, first check that the rate matches the tax year, then gather proof of your business miles and reply by the date on the letter. Where you find an error, correct it yourself before HMRC does, because early disclosure usually means a smaller penalty or none at all.

This guide is for self-employed ride-hailing and private hire drivers who use the simplified mileage rate. It covers why HMRC writes about mileage, what evidence works, how to rebuild a missing log from app and MOT data, and how to amend a return. If you have already had a letter about your 55p mileage allowance, our HMRC support team can deal with HMRC for you.

Key takeaways

• The 55p rate covers the first 10,000 business miles from 6 April 2026, with 25p after that. Any mileage before 6 April 2026 uses 45p.
• The flat rate replaces fuel, insurance, repairs and servicing for that car. Claiming those costs as well is a common reason for a disallowed claim.
• Once you use the flat rate for a car, you must keep using it while that car stays in your business.
• A missing log can often be rebuilt from driver app trip data, odometer readings and bank records, as long as you label it as reconstructed and explain your method.
• Correcting a mistake before HMRC finds it is almost always cheaper than waiting for a compliance check.

What is the 55p mileage allowance?

The 55p mileage allowance is HMRC's simplified flat rate for self-employed people who use a car or van for business. From 6 April 2026 you deduct 55p for each of the first 10,000 business miles and 25p per mile after that, instead of claiming actual running costs.

According to HMRC's guidance on simplified expenses for vehicles, the 2026/27 rates for cars and goods vehicles are 55p and 25p, and the rates before 6 April 2026 were 45p and 25p. The government's policy paper on increasing mileage rates, published 17 June 2026, confirms the rise is retrospective to 6 April 2026. For the wider background on the new rate, read our 2026 mileage allowance and Making Tax Digital update.

Why would HMRC question a 55p mileage allowance claim?

HMRC questions mileage claims when the numbers look out of line. Typical triggers are a mileage deduction that wipes out most of your profit, the 55p rate used on a 2025/26 return, mileage and fuel claimed together, or business miles that look high against the total miles a car could plausibly cover. A letter is a request to explain, not proof you did anything wrong.

The 55p mileage allowance is often the biggest single deduction a driver makes, so it attracts attention. A driver claiming 15,000 business miles has a deduction of £6,750 at the 2026/27 rates. That is a large figure set against the income on the same return, and HMRC can compare it with other information it holds.

The letter you receive matters. Some letters simply ask you to check your return and correct it if needed. Others open a formal compliance check, sometimes called an enquiry, and ask for specific documents by a fixed date. Read the heading and the first paragraph carefully, because they tell you which kind you have.

Which mileage rate applies to which tax year?

Use 45p per mile for the first 10,000 business miles driven before 6 April 2026, and 55p for the first 10,000 business miles from 6 April 2026. The 25p rate above 10,000 miles has not changed. That means your 2025/26 return, due online by 31 January 2027, must still use 45p.

The 2025/26 trap for drivers filing this winter

Most drivers are filing their 2025/26 return right now, months after the 55p headlines. It is easy to type 55p into a spreadsheet or software out of habit. On 10,000 business miles that overstates the deduction by £1,000, which is exactly the kind of mismatch an HMRC check can pick up.

Before you submit, look at the rate in every formula and template you use, because the 55p mileage allowance belongs only on 2026/27 and later figures. If you already filed with 55p, amend the return rather than waiting to see whether HMRC notices. Our list of key tax dates for ride-hailing drivers shows the deadlines for each year.

Accounts that do not end on 5 April

Most sole traders now report on a tax-year basis. If your accounts run to a different date, for example 31 December, some of your mileage in one set of accounts falls before 6 April 2026 and some after. Apply 45p to the earlier miles and 55p to the later ones. The apportionment rules for other year ends can be fiddly, so check GOV.UK or ask an accountant before you file.

What evidence does HMRC expect for a mileage claim?

HMRC expects you to show how many business miles you drove and how you worked that number out. A dated log of journeys is the best evidence. Where a log is incomplete, supporting records such as app trip histories, odometer readings, service invoices and bank statements can back up a reasonable, clearly explained figure.

You do not need fuel receipts to support a 55p mileage allowance claim, because fuel is not what you are claiming. What you need is evidence of distance and purpose. For a full breakdown of what a log should contain, see our guide to HMRC mileage log records and bookkeeping; this article focuses on what to do once HMRC is already asking.

• Your mileage log or app export for the year in question, showing dates and miles.
• Annual trip or earnings statements from your driver app, which link miles to paid work.
• Odometer readings at the start and end of the year, or the nearest MOT or service reading.
• Proof of which car you used, such as the V5C logbook, finance agreement or private hire vehicle licence.
• A short written note explaining how you separated business miles from private miles.

According to GOV.UK guidance on how long to keep your records, sole traders must keep records for at least 5 years after the 31 January submission deadline of the relevant tax year. For 2026/27, that means keeping your mileage evidence until at least the end of January 2033.

How do you rebuild a mileage log from app and MOT data?

You rebuild a log by combining what your driver app recorded, what your odometer shows and what you know about your working pattern. Start from total miles, work out the business share using trip data and dead miles between jobs, and write down every assumption. A reconstructed log must be labelled as such and never presented as a log kept at the time.

GOV.UK says that if you cannot replace your records, you must do your best to provide figures and tell HMRC if they are estimates. An honest, well-explained estimate is far easier to defend than a neat log typed up the night before a reply is due. Follow these steps:

1. Fix the period. Write down the exact dates HMRC is asking about, usually one tax year from 6 April to 5 April.
2. Find total miles. Take odometer readings from the nearest MOT, service or tyre invoices either side of the period. The government's MOT history checker shows the mileage recorded at each test.
3. Download your app history. Export trip or earnings statements from every driver app you used. Total the trip distances for the period, month by month.
4. Estimate dead miles. Add the miles driven between jobs while logged on and available, such as driving to a pickup. Base this on a sample of real shifts, for example two typical weeks, and show your workings.
5. Remove private use. Subtract school runs, shopping trips, holidays and ordinary trips that were not part of your driving work. If a second household car covers most private use, say so.
6. Cross-check with spending. Compare your business miles with fuel or charging spend on your bank statements. The figures should tell a consistent story, even though you are not claiming the fuel.
7. Write a method note. Put your sources, sample weeks and assumptions on one page. Mark the result clearly as a reconstruction made on a stated date.
8. Apply the right rate. Use 45p, or the 55p mileage allowance, for the first 10,000 business miles depending on when the miles were driven, then 25p above that.

Treat what counts as business mileage with care. Our guide to ride-hailing driver allowable expenses explains which journeys usually qualify. If your rebuilt figure is lower than the one you filed, that is a reason to correct the return, not to stretch the assumptions.

Can you claim fuel, insurance and repairs on top of the 55p rate?

No. For a car on the flat rate, the 55p or 25p per mile replaces the actual costs of buying and running it, including fuel, insurance, repairs and servicing. Claiming those costs as well counts the same expense twice. You can still claim parking and other travel costs, such as train fares, on top of the mileage figure.

HMRC's Business Income Manual at BIM75005 says the mileage rate covers the costs of buying, running and maintaining the vehicle, including depreciation. It also says you cannot use the mileage rate for a car if capital allowances have ever been claimed on it. Cars designed for commercial use, such as black cabs, are excluded altogether.

Double claims often creep in through bookkeeping rather than intent. A card payment at a garage gets coded as a business expense, and the same car is also on the flat rate. In an enquiry, HMRC will usually remove the duplicate costs, so check your expense categories line by line before you reply.

Can you switch to actual costs if HMRC challenges your claim?

Usually not for the same car. GOV.UK says that once you use the flat rates for a vehicle, you must continue to do so while you use that vehicle in your business. HMRC's manual adds that you can only move to actual costs when the vehicle is replaced. Switching methods mid-enquiry to rescue a claim is unlikely to work.

This rule cuts both ways for the 55p mileage allowance. A driver who chose the flat rate on a car bought two years ago is tied to it for that car, even after the 55p rise made it more generous. A driver who has claimed capital allowances on a car cannot move to the flat rate for that car. When you change vehicles, run both methods through our mileage calculator before you decide, because the choice will stick.

How do you correct a mileage error on your tax return?

You amend the return online or on paper. GOV.UK says you can usually correct a tax return within 12 months of the Self Assessment deadline, so a 2025/26 return can normally be changed until 31 January 2028. After that, or for older years, you write to HMRC instead, and claims for overpaid tax have a four-year limit.

According to GOV.UK's page on correcting a tax return, you must wait 72 hours after filing before you can update a return online. If your amendment increases the tax due, pay the extra as soon as you can, because HMRC can charge interest on tax paid late. If it reduces the tax, HMRC may ask for evidence before refunding.

If HMRC has already opened a compliance check into that year, do not simply amend and hope. Tell the officer what you have found and how you worked it out. Volunteering the correction during the check still counts in your favour when HMRC considers any penalty.

How long can HMRC open an enquiry into your mileage?

For a return filed on time, HMRC's Self Assessment Manual (SAM31100) says the enquiry window runs for 12 months after HMRC receives it. For a late return, the window ends on the quarter date after the first anniversary of filing. HMRC can still assess older years in some cases, such as where it discovers tax has been lost.

Filing early does not let you dodge a check, but it does start the clock sooner. A 2025/26 return filed on 15 November 2026 would normally be outside the standard enquiry window by 15 November 2027. That is why the 5-year record rule matters more than the enquiry window: HMRC can ask for records in other situations, so keep them.

What should you do when an HMRC mileage letter arrives?

Read the letter, note the reply date and work out whether it is a request to check your figures or a formal compliance check. Then gather your evidence, test your own claim honestly and reply on time. If you need longer, ask HMRC before the deadline. Never ignore the letter, because silence tends to make the outcome worse.

HMRC's factsheet CC/FS1a on compliance checks says HMRC may agree extra time if there is a good reason, and that you can appoint an adviser to deal with HMRC for you. It also says you must keep filing returns and paying tax that falls due while a check is open. Helping HMRC and telling it about any error straight away can reduce a penalty.

• Keep a copy of every letter and note the officer's name and reference.
• Answer only the questions asked, with copies of documents, never originals.
• If something is wrong, say so plainly and show the corrected figure.
• If you cannot provide an item, explain why and offer the next best evidence.

Illustrative example: a driver corrects a 55p claim

This is an illustrative example with an invented driver and invented figures. Kieran is a self-employed private hire driver who uses the flat rate on his own car. He filed his 2025/26 return in October 2026 and used 55p on all of his first 10,000 business miles, because his spreadsheet had already been updated for the new rate.

Kieran claimed 12,400 business miles. His filed deduction was 10,000 x 55p = £5,500, plus 2,400 x 25p = £600, giving £6,100. The correct 2025/26 deduction is 10,000 x 45p = £4,500, plus 2,400 x 25p = £600, giving £5,100. He overclaimed by £1,000.

His business mileage also needed checking, because he had no daily log for the spring. His app statements showed 8,950 trip miles. MOT and service readings showed 21,300 total miles for the year. A two-week sample of real shifts suggested dead miles of about 38.5% of trip miles, roughly 3,450 miles, giving a rebuilt total of 12,400 business miles.

Because the rebuilt mileage matched his claim, only the rate was wrong. Kieran amended the return to show a £5,100 deduction and paid the extra tax. His 2026/27 claim will use the 55p mileage allowance correctly. As a basic-rate taxpayer, the Income Tax on the extra £1,000 of profit is £200 at 20%, with Class 4 National Insurance on top at the rate set for that year. He kept the method note with his records in case HMRC asks.

Common mistakes and the penalty each can trigger

• **Using the 55p mileage allowance on 2025/26 mileage.** The overclaim is removed and you pay the extra tax plus interest. A penalty may follow if HMRC decides you did not take reasonable care.
• **Claiming fuel, insurance or repairs as well as the flat rate.** The duplicate costs are disallowed, and repeated double claims make a careless-error penalty more likely.
• **Presenting a rebuilt log as a log kept at the time.** This can turn an honest estimate into a deliberate inaccuracy, which carries much higher penalties.
• **Ignoring an HMRC letter.** HMRC can issue a formal information notice, which you cannot ignore, and non-compliance can bring further penalties (check GOV.UK for current amounts).
• **Swapping to actual costs mid-enquiry for the same car.** The switch is not normally allowed, so the claim can be reduced with nothing to replace it.
• **Not keeping records for five years.** Without evidence, HMRC may reduce or remove the whole mileage deduction.

Penalty levels for inaccurate returns depend on behaviour and on whether you disclosed the problem before HMRC found it. HMRC publishes the current rules in factsheet CC/FS7a on GOV.UK, so check the latest version rather than relying on figures quoted elsewhere.

Key terms

• **Simplified expenses:** flat-rate deductions that replace actual costs, including the mileage rate for cars and vans.
• **Compliance check (enquiry):** a formal HMRC review of a return or claim, usually by letter, with a deadline to provide information.
• **Enquiry window:** the period in which HMRC can normally open a compliance check into a Self Assessment return.
• **Dead miles:** miles driven while working but without a passenger, such as heading to a pickup.
• **Capital allowances:** tax relief on the cost of a vehicle or equipment; claiming them on a car rules out the flat rate for that car.
• **Class 4 National Insurance:** National Insurance paid by the self-employed on profits above a set threshold.

How UK Driver Accountants helps

We work only with drivers, on fixed fees from £20 a month, and we are independent of any ride-hailing app. If HMRC has written about your mileage, our HMRC support service reviews the letter, rebuilds your mileage evidence and handles the replies. We can also amend past returns and set up a simple routine so next year's claim is easy to defend. See our pricing for the current plans.

If you run your driving through a company rather than as a sole trader, different rules apply to mileage. Our guide to mileage allowance for limited company drivers covers that route.

Next steps

A letter about your 55p mileage allowance is a problem you can usually fix with a clear method and an honest reply. Check the rate for each tax year, rebuild what you are missing and correct errors before HMRC asks. If a reply deadline is close, contact our team and we will tell you what to send.

Last reviewed 2 November 2026 by the UK Driver Accountants tax team

This article is general information and not personal tax advice. Rates and rules can change, so check GOV.UK and speak to a qualified accountant about your own circumstances. Where HMRC opens a compliance check, disputes a claim or proposes a penalty, professional representation is recommended.