Methodology

How the calculators work

Each calculator takes a small number of inputs — such as gross salary, dividend income, or a VAT amount — and applies the relevant UK tax rules to produce a clear breakdown. Calculator figures are processed in your browser and are not sent to us. We use limited, privacy-controlled analytics for aggregate site usage; see our privacy policy for details.

Tax-year logic and configuration

Every calculator is built around a central tax-year configuration that defines the rates, thresholds, and allowances for the active tax year. Earned-income bands are selected by region, with separate Scottish and England/Wales/Northern Ireland schedules. UK-wide Personal Allowance, National Insurance, dividend allowances and VAT rates remain separately configured. When official rates change, we update this configuration so all calculators stay in sync.

What assumptions are used

Each calculator lists its assumptions clearly. Common assumptions include: you are a UK resident for tax purposes, you have one source of employment income, and you receive the standard personal allowance. Where a calculator simplifies something, it says so. We do not hide complexity — we scope it.

How the PAYE tax-code calculator differs

The PAYE calculator has a separate pay-period contract. It parses a supported tax code, applies HMRC's weekly or monthly Table A pay adjustment, rounds taxable pay down to whole pounds, apportions the tax bands to the period, and applies the 50% regulatory limit. Cumulative mode uses pay and tax totals from before the current payment; W1, M1 and X emergency treatment deliberately ignores them. Its full-year code projection is shown separately from the current-period deduction.

How self-employed tax is attributed

The self-employed calculator treats the entered figure as taxable trading profit after allowable expenses and any trading allowance. It calculates Income Tax on profit as the difference between tax on all entered non-savings income and tax on other income alone. This marginal method places the profit in the right bands and captures Personal Allowance tapering without presenting tax on other income as part of the profit estimate. Class 4 National Insurance is then calculated separately from the published annual profit limits.

How employer cost is budgeted

The employer-cost calculator adds salary and cash bonus before applying the selected category's annualised employer Class 1 National Insurance threshold and rate. It then adds the employer pension amount and other annual cash costs entered by the user without applying tax treatment to those entries. Employment Allowance is deliberately not allocated to one employee because it is claimed against an eligible employer's wider National Insurance bill.

How property income tax is estimated

The property-income calculator treats every amount as the user's own share. Actual-expense mode deducts entered allowable running costs but keeps residential finance costs outside taxable profit; it then estimates the 20% finance-cost tax reduction using the lowest of entered finance costs, property profit and adjusted total income above the Personal Allowance. Property-allowance mode deducts up to £1,000 instead of actual expenses and applies no finance-cost tax reduction. Income Tax on the resulting profit is the difference between tax with and without that profit, using the selected regional bands.

How bonus and overtime deductions are compared

The bonus-and-overtime calculator runs the annual salary model twice with identical tax year, region, NI category and loan settings: once on base salary and once after adding the extra cash pay. The differences are the marginal Income Tax, employee NI, loan deductions and take-home attributable to that extra pay. Overtime mode first multiplies the entered normal hourly rate by total annual overtime hours and the pay multiplier. Employer NI is compared separately and never reduces employee take-home.

How director salary and dividends are traced

The director calculator starts with entered company profit before one director's pay, deducts the chosen salary and annual-method employer National Insurance, and calculates Corporation Tax on the remainder. For the simplified twelve-month single-company case it applies the 19% small-profits rate, 25% main rate or the published 3/200 marginal-relief formula. It assumes every remaining post-tax pound is legally distributable and paid as a dividend, then adds the director's net salary and net dividend. Other personal income, Employment Allowance, associated companies, reserves, short periods and specialist reliefs are deliberately excluded.

What these calculators do not cover

These tools are designed for common, straightforward scenarios. The salary calculator models Scottish rates only for earned income; savings and dividends continue to use UK-wide rules. Its employer-cost view includes secondary Class 1 NI for supported categories but excludes Employment Allowance, benefits and director-specific annual methods. The PAYE calculator rejects K, M, N, NT, Scottish SD2/SD3 and other specialist codes and does not model benefits, irregular payroll intervals or payroll corrections. The self-employed calculator is not a full Self Assessment calculation: it excludes PAYE already paid, payments on account, student loans, losses, capital allowances, VAT, benefits, savings, dividends, Capital Gains Tax, employed/self-employed NI annual-maximum adjustments, State Pension age rules and specialist Class 4 cases.

Limitations and when to verify

These calculators use simplified models that cover common cases well but cannot account for every circumstance. Results should be treated as estimates. Verify with HMRC or a qualified adviser if your situation involves:

• Multiple income sources or employments
• Complex reliefs, pension contributions, or cross-border obligations
• Irregular income or edge cases not modelled here
• High-value decisions where accuracy is critical

Tax year currently used