United KingdomEmployee and employer NI are separately rounded using the exact percentage method. Current Lower Earnings Limits, voluntary Class 2 rates and profit thresholds are included. Pension-age, under-21 and apprenticeship categories require the relevant conditions; an annual director estimate is separate from normal payroll.
Formula
Class 1 employee A/M/H: 8% between the Primary Threshold and Upper Earnings Limit, then 2%; C: nil. Employer: 15% above the applicable secondary threshold. Class 4: 6% on £12,570–£50,270 profit, then 2%. Eligible voluntary Class 2: weekly rate × payable weeks.
When to use this calculator
National Insurance depends on whether you are reviewing employee, employer, director or self-employed contributions. This calculator keeps those roles separate, helping explain why a payroll cost for an employer is not the same as a deduction from the employee's salary.
Information to prepare
Confirm tax year, pay frequency and the applicable category or contribution class. For directors, check the full-year scope of the available calculation. For self-employment, prepare the relevant profit and any voluntary weeks requested rather than treating turnover as contribution profit.
How to interpret the result
Contribution earnings can differ from cash salary or business receipts. Caps, covered periods and personal conditions may affect individual components separately. Distinguish employee contributions, employer liabilities and other deductions: they do not necessarily reduce the same amount or belong to the same person. Match each component to its base and period before interpreting the combined result as employer cost or available employee cash. An income-tax allowance does not automatically create the same exemption from social contributions.
A practical comparison
When comparing a payslip with employer costs, keep the two contribution results on separate lines. Income Tax uses a different calculation and should be added only when you are building an appropriately scoped overall estimate. National Insurance alone cannot establish the amount deposited after every payroll deduction.
Check your calculation step by step
- Match the figures to the selected period and use GBP for monetary inputs. If you start with a document in another currency or covering several periods, resolve that difference before entering a combined amount.
- Calculate the documented case first. Then change one input at a time to compare scenarios. Keep the original values available so a change in the result can be traced to a particular assumption rather than several simultaneous edits.
- Read the component breakdown alongside the formula and examples below. If an official document differs, check the date, base, rounding and omitted concepts before changing a rate or treating the difference as an error.
Continue with a related calculation
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Official sources
- HMRC: current and historical NI rates and thresholdsConsulted: 2026-09-14
- HMRC: self-employed National InsuranceConsulted: 2026-09-14
- HMRC: exact percentage and separate roundingConsulted: 2026-09-14
- HMRC: when NI stops after State Pension ageConsulted: 2026-09-14
- HMRC: CA38 2026 contribution categoriesConsulted: 2026-09-14