How it works

We built this because the Budget changed the numbers and the old ones are still everywhere. From 6 April 2026 the car rate rose to 55p for the first 10,000 business miles (announced as a temporary rate in May), and Budget 2026 made it permanent. But the return you file in January 2027 still uses 45p, because it covers 2025-26. Enter your miles, pick the tax year and the vehicle, and the calculator gives you the deductible amount and the tax it saves at your marginal rate. Nothing you type leaves your browser. There is no account, no upload, and nothing is stored.

With the defaults, 12,000 business miles in a car in 2026-27 gives £6,000 to deduct: 10,000 miles at 55p (£5,500) plus 2,000 miles at 25p (£500). At the 20% basic rate that saves £1,200 of tax. The same 12,000 miles in 2025-26 gives £5,000, and in 2027-28 it gives £6,200, because the rate above 10,000 miles rises to 35p from 6 April 2027. Our Autumn Budget 2026 guide explains that change in full.

Pick the right tax year

This is the one mistake that costs real money. The rate follows the tax year the miles belong to, not the year you do the paperwork. Filing the 2025-26 return in January 2027? Use 45p. Logging miles you drive today? Use 55p. Planning miles from April 2027? Use 55p for the first 10,000 and 35p above that. The calculator labels each year with the job it belongs to, so you do not have to remember the numbers. If you are unsure which year a trip falls in, the date of the journey decides it, not the date you write it up. If your accounting period does not line up with the tax year, the profit has to be apportioned between the years.

Who can use the flat rates

Simplified expenses are open to sole traders and business partnerships (excluding partnerships with a corporate partner). They are not open to limited companies, and they do not cover a vehicle you have already claimed capital allowances for, or one you have already included as an expense when working out your business profits. Once you use the flat rates for a vehicle, you must keep using them for as long as that vehicle stays in the business. You can only switch to claiming actual costs when you replace the vehicle. The flat rate covers buying, running and maintaining the vehicle: fuel, oil, servicing, repairs, insurance, road tax and MOT, plus depreciation. Tolls, congestion charges and parking sit outside the rate, but you can claim those separately when the trip was solely for business. Only journeys that are wholly and exclusively for business count. The drive from home to your usual place of work is ordinary commuting, and it does not count. Keep a record of each business trip as you go. Miles reconstructed in January from a blank diary are miles HMRC can challenge.

Motorcycles use a single flat rate of 24p a mile in every year shown here, with no 10,000-mile split. Bicycles are not covered by simplified expenses at all: the scheme lists cars, goods vehicles and motorcycles only. If you cycle for work, claim the actual costs instead.

What this does not cover

  • Home working. The flat rates for working from home and for business premises are a separate part of simplified expenses, with their own rules. This calculator covers vehicles only.
  • Company cars. If the business is a limited company, or the car belongs to the company, different rules apply, including Advisory Fuel Rates. This calculator is for sole traders and partnerships using their own vehicle.
  • Which method is better. Flat rates suit some drivers and actual costs suit others. GOV.UK has a simplified expenses checker that compares the two for your figures. This calculator does not make that call for you.
  • Your tax bill. The deductible amount lowers your taxable profit. It is not a refund, and the tax saved shown here is an estimate at your marginal rate, not a figure HMRC has agreed. Our payment on account estimator works out whether the lower profit leaves you with payments on account, and when each one falls due.

Sources: HMRC, BIM75005: Simplified expenses: expenditure on motor vehicles (rates for 2025-26 and 2026-27, the worked examples, eligibility, the consistency rule, commuting); GOV.UK, Simplified expenses if you’re self-employed: Vehicles (2026-27 rates, the 11,000-mile example, costs covered and not covered); Budget 2026 (HC 726), via our Autumn Budget 2026 guide (35p above 10,000 miles from 6 April 2027). All read 3 November 2026. Rules can change, so confirm anything time-critical on GOV.UK or with an accountant before you act.

This is general information, not legal or financial advice. If the amount is large or the situation is disputed, get proper professional advice.