UK Bonus Tax Calculator

A UK bonus is normally taxed as employment income, not by a separate bonus tax. This calculator compares estimated take-home pay before and after the bonus, then treats the difference as the net bonus. That captures marginal income tax, employee NI and the personal allowance taper where relevant.

The important detail is where the bonus sits on top of salary. A bonus added to a basic-rate salary may mostly be taxed at 20% plus NI. A bonus added above the higher-rate threshold may be taxed at 40% plus NI. Between GBP100,000 and GBP125,140, the personal allowance taper can create an effective 60% income tax band before NI.

Use the result as a practical planning estimate for annual salary, bonus amount, marginal income tax, marginal national insurance, net bonus, effective deduction rate. The calculator is designed to make the main moving parts visible immediately, so it is most useful when you want to compare scenarios, sense-check a decision, or understand why one input changes the final result.

Before relying on the number, check whether your situation includes anything outside the calculator scope. Common examples are local rules, provider fees, payroll timing, special reliefs, bank holidays, tariff changes, exchange-rate markups, unusual tax codes, or personal circumstances that need official guidance or professional advice.

To make the estimate more accurate, use figures from the most recent bill, payslip, lender quote, receipt, official notice or provider screen you have. Rounded inputs are fine for quick comparisons, but precise inputs are better when you are deciding whether something is affordable or comparing two similar options.

Re-run the calculator whenever a key assumption changes, such as a new rate, different term, changed salary, updated threshold, extra fee, altered usage pattern or different date range. Keeping those assumptions fresh is often more useful than trying to make one calculation perfect.

If you are using the result for a formal decision, keep a note of the inputs you used and the date of the calculation. That makes it easier to compare the estimate with a later quote, bill, payslip or official calculation.