Sources and calculation assumptions
Our tools provide estimates for planning. They are independently operated and are not government services. Each financial tool identifies its year and relevant sources. Rates are maintained in the code; they do not update automatically.
United Kingdom: 2026/27
UK tax tools generally use 6 April 2026 to 5 April 2027. The take-home calculator annualises income; actual payslips can differ because of pay-period rounding, cumulative PAYE, tax-code adjustments and other deductions.
- HMRC employer rates and thresholds: income tax, National Insurance, statutory pay and student loans.
- HMRC business mileage rules: approved allowances are not a promise of cash reimbursement.
- Residential SDLT, Scottish LBTT and Welsh LTT: choose the relevant location and buyer circumstances.
Canada: 2026
Salary estimates model a full calendar year, including the basic personal amounts, CPP/QPP and EI parameters implemented in the tool. Individual credits, payroll frequency and mid-year withholding changes can change the result. These estimates do not replace a tax return.
- CRA T4127 payroll deductions formulas: annual rates and prorated second-half payroll rates can differ.
- Revenu Québec’s 2026 changes.
- GST/HST rates: exemptions and place-of-supply rules can affect a transaction.
United States: 2026
Income estimates cover the filing statuses offered by the tool. State estimates use simplified deductions and credits. Local income taxes, itemised deductions and many special circumstances are excluded. Annual tax can differ from paycheck withholding, including Additional Medicare withholding.
- IRS inflation adjustments: federal brackets, deductions and retirement limits.
- Social Security contribution and benefit base.
- State tables were compiled from the Tax Foundation and linked state sources. Check your state tax authority for your circumstances.
Loans, investments and files
Loan and investment tools use your inputs and the compounding method described on each page. They exclude fees, eligibility decisions and market changes unless explicitly included. Growth projections are hypothetical.
File tools use browser capabilities and bundled open-source libraries. Supported files are processed locally. Large files, encrypted PDFs, unsupported images or device memory limits may prevent processing. Work on copies and check downloaded results before discarding originals.
Corrections and updates
Key UK payroll and mileage, Canadian payroll, Québec and US federal reference pages were reviewed on 4 November 2026. This is not independent professional certification of every result or every state rule. Check the date and assumptions on your tool. If something looks wrong, report the tool, inputs and expected result, excluding private identifiers.