UK tax guides
Each guide explains the mechanics behind a calculator: what is deducted, in what order and why your payslip can still differ. Explanations only — not tax advice.
- Understanding PAYEUnderstanding PAYE: how your employer works out deductionsWhat PAYE does, why your tax code matters, and why two months of the same salary can differ.Reviewed 22 August 2026
- Income taxIncome tax explained: allowances, bands and marginal ratesHow the personal allowance, the bands and the £100,000 taper interact on earned income.Reviewed 22 August 2026
- National InsuranceNational Insurance explained: Class 1, Class 2 and Class 4How employee NI differs from the self-employed classes, and which thresholds apply.Reviewed 22 August 2026
- Salary deductionsWhat comes out of your salary, and in what orderPension, tax, National Insurance, student loan and net-pay deductions, in sequence.Reviewed 22 August 2026
- Self-employed basicsSelf-employed basics: revenue, allowable expenses and profitHow trading profit is worked out and why it, not revenue, drives your tax estimate.Reviewed 22 August 2026
- VATVAT explained: adding it, removing it and the registration thresholdHow to move between VAT-inclusive and VAT-exclusive prices without guessing.Reviewed 22 August 2026
- Contractor financesContractor finances: turning a target income into a day rateBillable days, non-billable time, expenses and tax, and how they set a sustainable rate.Reviewed 22 August 2026
- Tax terminologyUK tax terminology: a plain-English glossaryGross, net, taxable pay, marginal rate, effective rate and other terms used in the calculators.Reviewed 22 August 2026