Free Tool — 2026/27 UK Tax Year
Five questions. No signup, no email. See what unrecorded mileage and lost receipts cost you every year.
Profit means what's left after your business costs, not your total income.
Answer the questions and your figure appears here.
Start with your business miles or your monthly spend — either one is enough to see something.
HMRC taxes your profit, not your income. Every legitimate business cost you record comes off that profit before tax is worked out.
So a receipt you lose is not just a missing piece of paper. It is an expense you cannot claim, which means a higher profit on your tax return, which means a bigger bill.
Mileage works the same way. HMRC lets you claim a flat rate per business mile, but only for the journeys you actually logged. Trips you never wrote down are worth nothing at tax time.
HMRC mileage rates
First 10,000 miles
Cars and vans
Every mile after
Cars and vans
The 10,000 mile threshold resets each tax year on 6 April.
Expenses reduce your profit, so they cut your Income Tax and your Class 4 National Insurance at the same time. That combined rate is what an unclaimed expense really costs you.
Profit below £50,270
Basic rate Income Tax plus the main Class 4 NI rate.
Profit above £50,270
Class 4 NI drops to 2% above the upper profits limit, so the combined rate is 42%, not 46%.
Want your full tax bill?
Our Self Employed Tax Calculator works out your Income Tax, National Insurance and take-home pay from your income and expenses.
Outlays — free to start
Photograph a receipt and Outlays reads it, categorises it and files it ready for your tax return. Log a journey once and the mileage claim is worked out for you.