Current-year rates, clearly sourced
Each calculator names the tax year and the official rates it applies — for example the 2026/27 UK personal allowance of £12,570 and Class 4 NIC of 6% and 2%, or the 2026 IRS business mileage rate of 72.5¢ (Jan–Jun) and 76¢ (from 1 July 2026). Rates are editable so you can model other years.
Estimates — always confirm with HMRC, the IRS or an accountant
Tax rules have many exceptions (Scottish rates, student loans, state taxes, credits). These tools give a reliable estimate for planning and cash-flow, not a filing-ready return.
Frequently asked questions
Which tax year do the calculators use?
UK tools use 2026/27 (6 April 2026 – 5 April 2027). US tools use tax year 2026.
Do you store my income figures?
No. All calculations run in your browser.