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PARTLY

As of 13 August 2026, AI can only partly calculate your mileage allowance.

This still needs a person who signs their name to it.

Can you do it?

5 minutesto a draft.

15 minutesto something you’d act on.

Cost, all in£0

Skill neededchat-fluent

Who has to check ityou

What the alternative costsThe available tool data does not provide a price for an accountant or other mileage-calculation alternative.

If this goes wrong: you use the wrong rate or include an ineligible journey and submit an incorrect expense or tax claim.

What to actually do

  1. Hand it to a person

    The route this page recommends

    A person who owns the outcome does this end to end, worth it when the failure is dear.

  2. Use a tool built for this

    Second choice

  3. Do it yourself

    The distant third

    A chat interface, chat-fluent skill, and roughly 15 minutes until you can act on the result.

    How to actually do it

    1. Open the relevant mileage allowance guidance on GOV.UK and note the tax year and current rates that apply to your vehicle and journey type.
    2. Gather your mileage log, including the date, start and destination, business purpose, miles travelled, vehicle type and any passenger details.
    3. Record every amount your employer has already paid for those journeys, keeping employer mileage payments separate from any tax deduction you may be considering.
    4. Paste the prompt into a chatbot and replace each bracketed slot with your tax year, records, vehicle details, payments and the HMRC information you checked.
    5. Compare the model's rate for each row with the current GOV.UK guidance, then recalculate the row totals and overall balance using a calculator or spreadsheet.
    6. Remove journeys with missing evidence or unresolved eligibility, and ask an accountant or tax adviser to check the result before using it in a serious tax claim.

    Prompt

    Calculate my UK mileage allowance using only the information below and the current HMRC guidance or rates that I provide. First state whether I am calculating an employer mileage payment, a tax deduction, or both, and explain the difference. Then create a table showing each journey, eligible miles, applicable vehicle rate, gross allowance, amounts already reimbursed, and any balance or difference. Separate business mileage from journeys that may not qualify. Do not invent missing facts, rates or eligibility. Mark every missing or uncertain item, show the arithmetic for each total, and do not treat the result as tax advice. Use the relevant UK tax year: [tax year]. Vehicle type and engine or fuel details, if relevant: [details]. Mileage records: [dates, journey descriptions and miles]. Amounts already reimbursed: [amounts]. Any employer policy or HMRC rate information I have checked: [paste source or rates].

    Open it prefilled in ChatGPT or Claude, or copy it into Gemini, which takes no prefill link.

What it gets wrong

  • AI cannot reconstruct missing mileage or prove that a journey was for business.
  • AI cannot reliably decide every borderline question about whether a journey qualifies under HMRC rules.
  • AI cannot know that a rate is current unless you supply or verify the relevant GOV.UK guidance.
  • AI cannot take responsibility for an incorrect expense claim or tax return.
  • AI cannot automatically distinguish an employer reimbursement calculation from the separate rules for claiming tax relief unless you specify which result you need.

What caps this at PARTLY: legal accountability, judgement under ambiguity and verification cost.

How we scored this

Five axes, each scored nought to two by hand: ten means AI carries the task cleanly, and the thresholds that turn a total into YES, PARTLY or NO are published in the methodology. Each axis name links to its definition.

AxisScore (0–2)
Output2
Inputs1
Verification1
Liability1
Effort delta2
Total7 / 10

The methodology and its thresholds are published in full.

FAQ

Can AI calculate my mileage allowance?
Partly. AI can total your recorded miles and apply verified HMRC rates, but you must check the records, eligibility and final arithmetic. This is not professional advice.
Can I use AI to calculate mileage for HMRC?
You can use it to organise records and prepare a calculation, but check the result against current GOV.UK guidance before using it in a tax claim. An accountant or tax adviser should check a serious or complicated case.
What information does AI need to calculate mileage allowance?
It needs the relevant UK tax year, vehicle type, dates and descriptions of business journeys, miles travelled, passenger details where relevant, and amounts already reimbursed. It also needs enough information to separate eligible business travel from journeys that may not qualify.
Can AI tell me how much mileage tax relief I can claim?
It can show a provisional calculation if you provide your mileage, payments and the applicable HMRC guidance, but tax relief has separate eligibility rules from an employer mileage payment. This is not professional advice, so ask an accountant or tax adviser to check a material claim.

Nearby answers

All Tax returns & HMRC rulings

Assessed by gpt-5.6-luna (gpt-5.6-luna) on 2026-08-13, second-checked by an independent model. Wrong somewhere? Email [email protected] and it gets re-checked.

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