HMRC's simplified expenses mileage rates, calculated properly for the high annual mileage a working taxi or private hire driver actually does — not just the generic version built for occasional business trips.
HMRC's simplified mileage method pays 45p/mile for the first 10,000 business miles in a tax year, then 25p/mile for every mile after that. For most self-employed people who don't hit 10,000 miles, this rarely comes up. A working taxi or PHV driver doing 20,000–50,000+ miles a year spends most of the year at the lower 25p rate — this calculator does that split properly instead of assuming the whole year is at 45p, which would overstate your claim.
Important: once you choose the simplified mileage method for a vehicle, you must use it for that vehicle every year you own it — you can't switch to claiming actual costs (fuel, servicing, insurance, depreciation) partway through owning it. Compare carefully before your first tax return on a new vehicle.
This is a calculator, not tax advice. Rates shown are the standard HMRC simplified expenses mileage rates — always confirm current rates and your own circumstances at gov.uk before filing.