UK National Insurance Calculator 2025/26

Worked example

Example: an employee earning £45,000 in 2025/26.

1. Income above the £12,570 primary threshold: £45,000 − £12,570 = £32,430. All of this sits below the £50,270 upper earnings limit.
2. Class 1 employee NI at 8%: £32,430 × 8% = £2,594.40.
3. Nothing is earned above £50,270, so no 2% band applies.
4. Annual employee NI = £2,594.40, roughly £216.20 per month.

The same £45,000 as an employer's cost: secondary Class 1 NI is 15% on wages above the £5,000 secondary threshold: (£45,000 − £5,000) × 15% = £40,000 × 15% = £6,000. An eligible employer claiming the Employment Allowance could offset up to £10,500, reducing this employer NI to £0 for a single such employee.

If instead this were £45,000 of self-employed profit: Class 4 NI is 6% on profit between £12,570 and £50,270: £32,430 × 6% = £1,945.80, with no mandatory Class 2 to add.

How the UK National Insurance calculator works

National Insurance (NI) is a separate charge from Income Tax that funds the State Pension and contributory benefits. How much you pay depends on which class applies to you, and this calculator handles the three that matter to most people for the 2025/26 tax year: Class 1 for employees, secondary Class 1 for employers, and Class 4 for the self-employed.

Start by telling the calculator which role you are in. If you are an employee, enter your gross annual salary and it applies the Class 1 rules: 8% on earnings between the £12,570 primary threshold and the £50,270 upper earnings limit, then 2% on anything above £50,270. If you are self-employed, enter your annual taxable profit (turnover minus allowable expenses) and it applies Class 4: 6% between £12,570 and £50,270 and 2% above. If you are an employer, enter each employee's gross pay and it works out secondary Class 1 at 15% on everything above the £5,000 secondary threshold.

Because NI is banded rather than a single flat percentage, your effective rate is always lower than the headline figure. Someone on £30,000, for example, only pays the 8% employee rate on the £17,430 above the primary threshold, not on the whole salary. The calculator does this banding automatically and returns an annual figure you can divide by 12 or 52 for a monthly or weekly amount. All thresholds used are the frozen 2025/26 HMRC figures, which remain aligned with the Income Tax personal allowance and higher-rate threshold.

Class 1 employee NI versus Class 4 self-employed NI

The most common question this calculator answers is why an employee and a self-employed person on the same income pay different amounts. The thresholds are identical — both start at £12,570 and both switch to the 2% rate above £50,270 — but the main rate differs: employees pay 8% Class 1 while the self-employed pay 6% Class 4. On £40,000 that is a £548.60 difference in NI (£2,194.40 versus £1,645.80) for the same earnings.

That gap reflects the fact that employees and the self-employed build up different benefit entitlements, and that an employee's work also triggers a large employer NI bill on top. There is no employer contribution behind self-employed profits, so the headline Class 4 rate is set lower.

A second difference is Class 2. Historically the self-employed paid a flat weekly Class 2 charge as well as Class 4. From 6 April 2024 mandatory Class 2 was effectively removed: if your profits are above the £6,845 Small Profits Threshold for 2025/26 you are treated as having made Class 2 contributions without paying anything, so your NI is just the Class 4 figure this calculator shows. If your profits are below £6,845 you pay no Class 4 at all, but you can choose to pay Class 2 voluntarily at £3.50 a week (about £182 a year) to keep that year qualifying for the State Pension.

For employees there is no equivalent voluntary top-up needed while working, because Class 1 is deducted automatically through PAYE. If you have a mix of employment and self-employment, run the calculator once for each income stream and add the results — an annual maximum can cap the combined total in unusual cases, but for typical incomes the two simply stack.

Employer National Insurance and the Employment Allowance

Employer NI changed significantly from 6 April 2025 and this calculator uses the new figures. The secondary Class 1 rate rose from 13.8% to 15%, and the secondary threshold — the point at which employer NI starts — was cut sharply from £9,100 to just £5,000 a year. Together these mean employing staff costs noticeably more than in 2024/25, and the increase bites hardest on lower-paid and part-time workers who previously fell under the old threshold.

To calculate it, enter the employee's gross annual pay and select the employer option. The calculator charges 15% on every pound above £5,000. On a £30,000 salary that is (£30,000 − £5,000) × 15% = £3,750 of employer NI, entirely separate from the £1,394.40 the employee pays themselves.

The offsetting relief is the Employment Allowance, which rose from £5,000 to £10,500 for 2025/26. Eligible businesses and charities can reduce their total annual employer NI bill by up to this amount. From April 2025 the old rule barring employers with more than £100,000 of secondary NI liability was scrapped, so many more businesses can now claim. Select "Yes" for the Employment Allowance and the calculator subtracts up to £10,500 from the employer NI total, never taking it below zero.

A few conditions apply that a calculator cannot check for you: the allowance is per business, not per employee; sole director-only companies with no other employees generally cannot claim; and public-sector work and certain connected companies are restricted. Use the employer figure here for budgeting, then confirm eligibility against the HMRC guidance before you claim through your payroll software.

National Insurance, the State Pension and qualifying years

Paying National Insurance is not just a tax — it builds your entitlement to the new State Pension and to benefits such as contribution-based Jobseeker's Allowance and Maternity Allowance. This is why the calculator's Class 2 handling matters even though the amounts look small. To get any new State Pension you generally need at least 10 qualifying years on your NI record, and 35 qualifying years for the full amount.

As an employee, any week you earn at or above the Lower Earnings Limit (£125 a week in 2025/26) counts towards a qualifying year even if your pay is below the £242 primary threshold where you actually start paying the 8%. That is a deliberate feature: low earners can build State Pension entitlement without paying anything. The self-employed reach a qualifying year through Class 4, or through voluntary Class 2 at £3.50 a week when profits are under £6,845.

If you have gaps — years abroad, time on a low income, or a career break — you may be able to fill them with voluntary Class 3 contributions, which are more expensive than Class 2. This calculator focuses on the mandatory Class 1 and Class 4 amounts you owe on current earnings rather than back-filling old years, so treat it as a forward-looking estimate of this year's contributions. To see your actual record, gaps and forecast, check your personal tax account on GOV.UK.

Finally, remember these 2025/26 thresholds are frozen until at least April 2028 for the secondary threshold and until 2031 for the main personal allowance and higher-rate limit. As wages rise, more of your income falls into the charged bands over time — a phenomenon known as fiscal drag — so it is worth re-running the calculator each year even if the headline rates do not change.

Frequently asked questions