How it works
What National Insurance actually pays for
This National Insurance calculator runs the exact 2025/26 NI bill that HMRC will take from your gross pay — Class 1 for employees, Class 4 for the self-employed, voluntary Class 3 top-ups if you want to buy qualifying years. Pair it with the PAYE salary calculator, the income tax calculator and the student loan calculator to see the full deduction stack on a single page.
Although it looks like just another tax on your payslip, NI directly buys specific entitlements — most importantly your State Pension qualifying years. A full new State Pension requires 35 qualifying years of contributions, and you need at least 10 years to get any at all. It also feeds the NHS, Jobseeker's Allowance, Maternity Allowance, Bereavement Support and a handful of other contributions-based benefits.
Unlike Income Tax, NI does not stack with allowance tapers, savings allowances or Marriage Allowance. It's a separate calculation running in parallel.
Class 1: employees
For 2025/26, employees pay Class 1 NI on their gross pay above the Primary Threshold of £12,570 a year (£242/week, £1,048/month) and below the Upper Earnings Limit of £50,270 at 8%, and at 2% on anything above that.
| Band | Annual range | Rate |
|---|---|---|
| Below threshold | Up to £12,570 | 0% |
| Main band | £12,571 – £50,270 | 8% |
| Upper band | Above £50,270 | 2% |
Example: £40,000 salary
Earnings above threshold: 40,000 − 12,570 = £27,430.
27,430 × 8% = £2,194.40 a year Class 1 NI.
Employer also pays around £4,250 of Secondary Class 1 NI separately — not deducted from your pay but a real cost of employing you.
Example: £80,000 salary
Main band 50,270 − 12,570 = 37,700 × 8% = £3,016.
Upper band 80,000 − 50,270 = 29,730 × 2% = £594.60.
Total NI = £3,610.60 — around 4.5% of gross.
Class 2 and Class 4: self-employed
From April 2024, Class 2 NI (a flat £3.45/week) was effectively abolished for self-employed earning above the Small Profits Threshold — those people still get a qualifying year without paying. Anyone earning below it can still pay voluntary Class 2 (£3.50/week for 2025/26) to build entitlement.
Class 4 NI is the main bill. For 2025/26:
| Band | Annual profit | Rate |
|---|---|---|
| Below threshold | Up to £12,570 | 0% |
| Main Class 4 | £12,571 – £50,270 | 6% |
| Upper Class 4 | Above £50,270 | 2% |
Voluntary contributions (Class 3)
If you've got gaps in your NI record (career breaks, time abroad, very low earnings) you can plug them with Class 3 voluntary contributions — £17.75/week for 2025/26. A single year typically costs about £924 to buy and can add up to ~£330/year of State Pension for life. For many people, it's among the highest guaranteed returns available.
Check your NI record and forecast on gov.uk/check-state-pension before paying — not every gap is worth filling, and HMRC is running a temporary extension to buy gaps back to 2006.
Directors and irregular earnings
Company directors use an annual NI calculation rather than monthly. This matters if pay is bonus-heavy or irregular — an even salary throughout the year would hit the threshold 12 times, whereas a lump-sum director payment near year-end only touches the main band once. Smart directors smooth the pay to maximise the threshold.
Common misunderstandings
- "NI is part of Income Tax." — No, they're separate calculations with different thresholds and rules. You can have an Income Tax code of zero and still pay NI.
- "Pensioners pay NI." — No, employees over State Pension age don't pay Class 1 NI. Employer still pays its share.
- "NI is refundable if I leave the UK." — Not directly, but your contribution record is retained and usable for State Pension if you ever qualify (10-year minimum).
- "Second job gets double NI." — Each job gets its own threshold, so you may inadvertently pay more NI across two small jobs than one big one. HMRC reconciles at year-end via PAYE coding.
How your NI letter affects the calculation
Your NI category letter appears on your payslip — A, H, M, Z, X and a handful more. Each letter changes how Class 1 is calculated and what the employer pays.
| Letter | Who it applies to | Effect |
|---|---|---|
| A | Most employees | Standard Class 1 rates |
| H | Apprentice under 25 | Employer pays no secondary NI up to £50,270 |
| M | Employee under 21 | Employer pays no secondary NI up to £50,270 |
| Z | Employee under 21 in contracted-out pension | Historical, almost extinct |
| C | Employee over State Pension age | 0% primary, employer still pays secondary |
| X | Employee below Lower Earnings Limit | No NI due |
NI for umbrella and agency workers
Tens of thousands of UK workers are paid via umbrella companies — particularly contractors, locum clinicians and supply teachers. An umbrella sits between the agency and the worker, paying through PAYE and deducting employer NI from the gross contract rate. Many contractors are shocked to see the assignment rate quoted by the agency is reduced by roughly 13–15 % before the umbrella even calculates personal tax — this is the employer Class 1 plus the Apprenticeship Levy being passed back to them.
A fair umbrella payslip shows the assignment rate, the deduction of employer NI, pension contributions and the Apprenticeship Levy, then the resulting gross salary and finally Income Tax and employee NI. The HMRC Check Your Payslip service helps you verify the numbers.
NI, maternity, paternity and parental leave
NI credits protect your contribution record when life events stop you from paying. If you're on Statutory Maternity Pay (SMP) you continue accruing qualifying years. While on Shared Parental Leave, Statutory Sick Pay or Carer's Allowance, you also receive credits. People claiming Child Benefit for a child under 12 automatically get Class 3 credits even if they earn nothing — valuable for stay-at-home parents, provided Child Benefit is actually claimed (even if waived due to the High Income Child Benefit Charge).
Expectant parents should also note that the first six weeks of SMP are paid at 90 % of average weekly earnings, then 33 weeks at the lower of £187.18/week or 90 % of earnings. NI is still deducted on any SMP above the Primary Threshold.
Working abroad and NI
Leaving the UK to work overseas raises important NI questions. Three situations come up most often.
Seconded by a UK employer for up to 24 months
An A1 certificate (or equivalent under the UK's bilateral social security agreements) lets you keep paying UK NI instead of the host country's contributions. Your pension record continues and you're exempt from local social security.
Moving permanently to another country
NI stops unless you voluntarily pay Class 2 or Class 3 from abroad. Class 2 (£3.50/week) is the bargain if you can qualify — cheaper than Class 3 (£17.75/week) and builds the same qualifying year. The test is whether you were ordinarily employed or self-employed in the UK before leaving.
Returning to the UK
Time abroad creates gaps, but you can fill them via Class 3 within six tax years (temporarily extended to cover 2006 onwards until April 2026). Many Brits coming back from the EU find they're still 2–3 qualifying years short of a full State Pension and close the gap cheaply with voluntary contributions.
NI and salary sacrifice — the invisible win
One of the biggest attractions of salary sacrifice (exchanging part of your cash salary for a benefit) is the NI saving on both sides. Sacrificing £5,000 into pension saves the employee 8 % (£400) in NI and the employer 13.8 % (£690) — many employers pass part of their saving back into the pension, effectively turbocharging the contribution. The same trick works for cycle-to-work, childcare vouchers (where still offered) and ultra-low-emission car schemes.
Where salary sacrifice is less appealing: once you drop below the Lower Earnings Limit through heavy sacrifice, you stop building NI credits. Very low-paid workers should be careful not to sacrifice themselves out of qualifying years.
A practical NI action list
A handful of small actions keep your NI record tidy and build long-term value.
- Check your NI record every two years at gov.uk/check-national-insurance-record.
- Request a State Pension forecast — it shows exactly how many qualifying years you still need.
- Use salary sacrifice for pension contributions when the employer offers it.
- Parents on leave: claim Child Benefit even if High Income Child Benefit Charge applies, to guarantee NI credits.
- Self-employed with low profits: pay voluntary Class 2 at £3.50/week to keep the qualifying year.
- Before buying gaps via Class 3, model the return — only worth it if you will actually reach 35 qualifying years and have a reasonable life expectancy to collect.
- Leaving the UK: apply for form CF83 to pay voluntary NI from abroad, usually cheaper than buying back later.
Reading your NI line on the payslip
UK payslips are notoriously dense. The National Insurance section hides more information than most workers realise.
- NI category — single letter indicating how your NI is calculated (A, H, M, etc.).
- NI-able pay this period — the part of your pay that falls above the Primary Threshold.
- NI-able pay year-to-date — cumulative amount for director-style annual calculations.
- Employee NI — what's deducted from your pay, usually 8 % of the band between thresholds.
- Employer NI — 13.8 % that does not come from your pay but is paid by the employer on top.
Employer NI and the Employment Allowance
UK employers pay 13.8 % secondary Class 1 NI on salaries above the Secondary Threshold (£9,100 a year) — a material chunk of the cost of hiring. Most small businesses can reduce this bill by up to £10,500 a year through the Employment Allowance, which is claimed automatically on the first relevant payroll submission.
Two exceptions matter: companies where the sole employee is also the director are not eligible, and companies with Class 1 liabilities above £100,000 in the previous tax year lose the allowance entirely. The allowance is one of the simplest quick wins for a genuinely small business and is often missed by new payrolls.