National Insurance Explained

National Insurance (NI) is one of the UK's most misunderstood taxes. Despite its name suggesting an insurance scheme, it functions as a payroll tax, automatically deducted from your pay alongside income tax. This guide explains what NI is, why you pay it, how it's calculated, and what you get in return.

If you are employed, NI is calculated and deducted by your employer through the PAYE system each pay period. If you are self-employed, you pay NI through your annual Self Assessment tax return. Either way, understanding how NI works is essential for knowing what your actual take-home pay will be each month.

What National Insurance Funds

NI contributions fund specific parts of the welfare state:

State Pension: The single largest NI expenditure. Your contributions build your entitlement to the State Pension when you retire.
NHS: A proportion of NI funds the National Health Service, though most NHS funding comes from general taxation.
Statutory benefits: Statutory Sick Pay, Maternity Allowance, Bereavement Support Payment, and contribution-based Jobseeker's Allowance and Employment and Support Allowance.

Unlike income tax (which goes into the general government pot), NI is nominally ring-fenced for these purposes through the National Insurance Fund. In practice, the distinction is increasingly blurred, and Treasury effectively manages both.

It is worth noting that NI does not fund means-tested benefits such as Universal Credit, Housing Benefit, or Council Tax Reduction. Those are paid from general taxation. The contributory principle behind NI means that your payment history determines your eligibility for certain benefits, most importantly the State Pension.

NI Classes Explained

There are several classes of NI, each applying to different groups:

Class	Who Pays	How It's Paid
Class 1 (Employee)	Employees earning above £12,570/year	Deducted from pay via PAYE
Class 1 (Employer)	Employers on employees' earnings above £5,000/year	Paid by employer to HMRC
Class 2	Self-employed with profits above £12,570/year	Paid through Self Assessment
Class 3	Voluntary contributions to fill gaps	Paid directly to HMRC
Class 4	Self-employed with profits above £12,570/year	Paid through Self Assessment

Class 1: Employees

Class 1 is the most common type. If you work for an employer and earn above the Primary Threshold (£12,570 per year in 2026/27), you pay employee NI at 8% on earnings between the Primary Threshold and the Upper Earnings Limit (£50,270), and at 2% on earnings above the UEL. Your employer separately pays 15% on your earnings above the Secondary Threshold (£5,000). Use the National Insurance Calculator to see your exact employee and employer NI breakdown.

Class 2 and Class 4: Self-Employed

If you are self-employed and your profits exceed £12,570 per year, you pay Class 2 NI (treated as paid automatically to protect your State Pension record) and Class 4 NI at 6% on profits between £12,570 and £50,270, then 2% on profits above £50,270. Class 2 is a flat-rate contribution that counts towards your qualifying years for State Pension purposes. Class 4 does not build any benefit entitlement; it is purely a tax on self-employed profits.

Class 3: Voluntary Contributions

Class 3 contributions are entirely voluntary. You pay them to fill gaps in your NI record, for example if you spent time abroad, were not working, or earned below the Lower Earnings Limit. In 2026/27, Class 3 costs £17.45 per week. We cover these in more detail in the section on filling gaps below.

Class 1 NI Rates for Employees 2026/27

Earnings Band	Annual Range	Employee Rate
Below Lower Earnings Limit	Up to £6,708	0% (no pension credit)
LEL to Primary Threshold	£6,708 – £12,570	0% (pension credit earned)
Primary Threshold to UEL	£12,570 – £50,270	8%
Above Upper Earnings Limit	Over £50,270	2%

The distinction between the LEL and PT is important: if you earn between £6,708 and £12,570, you don't pay any NI but you're treated as having paid it. This protects your State Pension record without costing you anything.

Employer NI Rates 2026/27

Employers pay Class 1 Secondary NI at 15% on all employee earnings above the Secondary Threshold of £5,000 per year. There is no upper limit; employer NI continues at 15% on all earnings above this threshold. This is a significant cost on top of your salary, and it is one reason why salary sacrifice pension schemes are popular: they reduce employer NI as well as employee NI. See our salary sacrifice guide for details.

Employers benefit from a £10,500 Employment Allowance that reduces their overall NI bill, though this is not available to all employers (single-director companies with no other employees are excluded, for example).

Worked Example: NI on a £35,000 Salary

Let's calculate the employee NI for someone earning £35,000 per year in 2026/27:

Earnings below the Primary Threshold (£12,570): £0 NI
Earnings between £12,570 and £35,000 = £22,430 at 8% = £1,794.40
No earnings above the UEL (£50,270), so the 2% rate does not apply

Total employee NI: £1,794.40 per year, or £149.53 per month.

On top of this, the employer pays 15% on earnings above £5,000: (£35,000 − £5,000) = £30,000 × 15% = £4,500 per year in employer NI. The total cost to the employer of this £35,000 salary is therefore £39,500 before any pension or other contributions.

You can run your own numbers using our Salary Calculator, which shows employee NI, employer NI, income tax, and your net take-home pay in one breakdown.

Worked Example: NI on a £65,000 Salary

For a higher earner on £65,000 per year:

Earnings between £12,570 and £50,270 = £37,700 at 8% = £3,016.00
Earnings above £50,270: £65,000 − £50,270 = £14,730 at 2% = £294.60

Total employee NI: £3,310.60 per year, or £275.88 per month.

Notice how the marginal NI rate drops from 8% to 2% once you pass the UEL. This is the opposite of income tax, which increases from 20% to 40% at a similar threshold. The combined marginal rate between £50,270 and £100,000 is therefore 42% (40% income tax + 2% NI). Above £100,000, you also lose your personal allowance, which creates an effective 62% marginal rate. See our income tax bands guide for a full explanation.

How NI Is Calculated: Per Pay Period, Not Annually

One crucial difference between NI and income tax is how they are calculated. Income tax works cumulatively across the tax year: HMRC tracks your total earnings and tax paid, adjusting each month to ensure you pay the right amount over the year. NI, by contrast, is calculated on each pay period independently.

If you are paid monthly, HMRC divides the annual thresholds by 12. For 2026/27, the monthly Primary Threshold is £1,047.50 (£12,570 ÷ 12) and the monthly UEL is £4,189.17 (£50,270 ÷ 12). Your NI is worked out on each month's pay against those monthly thresholds.

This per-period calculation has practical consequences. If your pay fluctuates (for example, you receive a large bonus in one month), you could pay more NI over the year than someone with the same total annual salary paid evenly. Unlike income tax, there is no year-end reconciliation for NI. What you pay each period is final.

This also matters if you have two jobs. Each employer applies the NI thresholds independently, which can sometimes lead to overpayment. If you earn above the UEL across both jobs combined but below it in each individual job, you may pay 8% on earnings that should only attract 2%. You can apply for a deferment from HMRC or claim a refund after the tax year ends.

NI and Your State Pension

Your NI record directly determines your State Pension entitlement:

35 qualifying years = full new State Pension (currently £221.20/week, £11,502/year).
10 qualifying years = minimum to get any State Pension.
Between 10 and 35 years: You get a proportional amount (e.g., 25 years = 25/35 of full pension).

A qualifying year is one where you either earned above the LEL, paid Class 2 NI, or received NI credits (e.g., while claiming Universal Credit, Child Benefit for a child under 12, or Carer's Allowance).

The State Pension increases each year under the triple lock: it rises by the highest of average earnings growth, CPI inflation, or 2.5%. This makes the State Pension a valuable entitlement and well worth protecting by ensuring you have a full NI record.

Checking Your NI Record

You can check your NI record online at GOV.UK. It shows:

How many qualifying years you have.
Any gaps in your record.
Your forecast State Pension amount.
Whether you can fill gaps with voluntary Class 3 contributions.

It is a good idea to check your record periodically, especially if you have changed jobs frequently, had periods of self-employment, or spent time outside the UK. Gaps can sometimes appear due to employer errors or because your earnings fell below the Lower Earnings Limit in a given year.

Filling Gaps with Voluntary Contributions

If you have gaps in your NI record (due to living abroad, being unemployed, or earning below the LEL), you can pay voluntary Class 3 contributions to fill them. The cost is £17.45 per week (£907.40 per year for 2026/27). Each additional qualifying year increases your State Pension by approximately £329 per year, making voluntary contributions excellent value if you're short of 35 years.

To put this in perspective: paying £907.40 to fill one gap year gives you an extra £329 per year in State Pension for the rest of your life. If you receive the State Pension for 20 years, that one year of voluntary contributions would return £6,580, a return of over 7:1 on your outlay. Very few investments offer that kind of guaranteed return.

You can usually fill gaps from the last 6 years. There's currently an extended deadline allowing gaps back to 2006/07 to be filled, but this deadline is expected to close soon. Check GOV.UK for the current deadline.

NI Credits: Getting Qualifying Years Without Paying

Not everyone needs to pay NI to get a qualifying year. The government awards NI credits in certain situations, including:

Claiming Child Benefit for a child under 12: the parent who claims receives Class 3 NI credits automatically.
Claiming Universal Credit, Jobseeker's Allowance, or Employment and Support Allowance: credits are awarded for the weeks you are claiming.
Caring for someone for at least 20 hours per week: Carer's Credit provides NI credits without needing to claim Carer's Allowance.
Jury service: credits are available for the period you serve.
Receiving Working Tax Credit: for those still on the legacy benefit system.

A common mistake is for a couple where one parent stays at home with the children but the other parent claims Child Benefit. If the stay-at-home parent is not named as the Child Benefit claimant, they miss out on the NI credits. This can leave them with gaps in their State Pension record that may only be discovered decades later.

NI When You Reach State Pension Age

Once you reach State Pension age, you stop paying employee NI entirely, even if you continue working. Your employer still pays employer NI on your wages, but nothing is deducted from your pay. This effectively gives you a pay rise of 8% (or 2% if you earn above the UEL) on the day you reach State Pension age.

For example, someone earning £35,000 who reaches State Pension age would save £1,794 per year in employee NI, boosting their monthly take-home pay by roughly £150. You still pay income tax as normal, and your employer still pays employer NI, but your personal deduction stops entirely.

The current State Pension age is 66 for both men and women. It's scheduled to increase to 67 between 2026 and 2028, and to 68 between 2044 and 2046 (subject to government review).

Reducing Your NI Through Pension Contributions

One of the most effective ways to reduce your NI bill is through salary sacrifice into a workplace pension. Under salary sacrifice, you agree to a lower contractual salary in exchange for higher employer pension contributions. Because your gross salary is reduced, both you and your employer pay less NI.

For example, if you earn £40,000 and sacrifice £5,000 into your pension, your NI is calculated on £35,000 instead of £40,000. That saves you £400 per year in employee NI (£5,000 × 8%), and your employer saves £750 in employer NI (£5,000 × 15%). Many employers pass some or all of the employer NI saving into your pension pot as an additional contribution.

Use our Pension Contribution Calculator to model exactly how much you could save through salary sacrifice, including both the income tax and NI benefits.

Note that salary sacrifice reduces your gross salary for all purposes, including mortgage applications, statutory maternity/paternity pay calculations, and any benefits linked to earnings. Make sure you understand the trade-offs before entering a salary sacrifice arrangement. Our salary sacrifice guide covers these in detail.

Common Mistakes and Misconceptions

"I pay NI so I'm entitled to all benefits." NI only gives you access to contributory benefits (State Pension, contribution-based JSA and ESA, Maternity Allowance). It does not entitle you to Universal Credit, Housing Benefit, or NHS treatment. Those are funded differently and have their own eligibility rules.
"I've paid NI for 35 years so I can stop." You cannot choose to stop paying NI. As long as you are employed or self-employed and below State Pension age, NI is mandatory. Having 35 qualifying years means you have the maximum State Pension entitlement, but it does not exempt you from the tax.
"NI and income tax thresholds are the same." While the Primary Threshold (£12,570) matches the income tax Personal Allowance, the employer NI threshold (£5,000) is much lower, and the UEL (£50,270) is aligned with the higher-rate income tax threshold. The thresholds serve different purposes and are set independently by the government.
"NI is calculated the same way as income tax." As explained above, income tax is cumulative across the year, while NI is calculated per pay period. This means overtime, bonuses, and irregular payments can result in different NI outcomes than you might expect.
"My student loan repayment is part of NI." Student loan repayments are a separate deduction, though they appear on your payslip alongside NI. They have different thresholds and rates, and are collected by the Student Loans Company, not HMRC's National Insurance Fund. See our student loan repayment guide for details.

NI vs Income Tax: Key Differences

Feature	Income Tax	National Insurance
Applies to	All income types	Employment/self-employment only
Rate direction	Increases with income	Decreases (8% → 2%)
Personal allowance taper	Yes (above £100k)	No
Age limit	Payable at any age	Stops at State Pension age
Benefit entitlement	No	Builds pension/benefit rights
Calculation basis	Cumulative (annual)	Per pay period
Applies to dividends	Yes	No
Applies to rental income	Yes	No
Applies to savings interest	Yes (above allowance)	No

This difference in scope is particularly relevant for company directors and landlords. If you pay yourself through dividends rather than salary, you avoid NI entirely on those payments, though you still pay income tax on dividends. This is one reason why many limited company directors pay themselves a small salary at or near the Primary Threshold and take the remainder as dividends. However, dividends do not count towards your NI qualifying years for State Pension purposes.

NI Letters and Categories

Your payslip will show an NI letter (also called a category letter). The most common are:

Category A: Standard rate for most employees. This is what the vast majority of workers are on.
Category B: Married women and widows who elected for reduced-rate NI before 1977. Very few people are still on this category.
Category C: Employees over State Pension age. Employee NI is zero; employer NI still applies.
Category H: Apprentices under 25. Employer NI is zero on earnings up to the Upper Secondary Threshold (£50,270).
Category M: Employees under 21. Similar employer NI relief as category H.

Your NI category is normally set correctly by your employer based on your age and circumstances. If you believe your category is wrong (for example, if you have passed State Pension age but are still being charged NI), contact your employer's payroll department immediately.

Calculators

National Insurance Calculator: See your NI breakdown for any salary
Salary Calculator: Full take-home pay with NI, income tax, and all deductions
Income Tax Calculator: Understand your income tax bill separately
Pension Calculator: See NI and tax savings from salary sacrifice
Take-Home Pay Calculator: Quickly see what you actually receive each month
Bonus Tax Calculator: Understand how NI applies to bonus payments
Two Jobs Calculator: Check for NI overpayment across multiple employments