What Is National Insurance?
National Insurance is a tax on the money you earn from work. You pay it if you are employed and earning above a set threshold, or if you are self employed and making a profit above a set level. It sits alongside Income Tax, but it is not the same thing, and the difference matters more than most people think.
The part that makes National Insurance different is what it buys you. Unlike Income Tax, which simply funds public spending, your National Insurance record is tied to your entitlement to the State Pension and certain benefits. Pay enough of it across enough years and you qualify for a full State Pension. Fall short, and you get less. So National Insurance is really two things at once: a tax you pay now, and a record that shapes what you can claim later.
It has been part of the UK system since 1911, originally as a genuine insurance scheme against unemployment and illness. Today the insurance idea is looser, but the link to the State Pension is still real, and that is why gaps in your record can cost you money decades down the line.
What National Insurance Pays For
Your National Insurance contributions count towards a specific list of benefits, the main one being the new State Pension. To get any State Pension at all you usually need at least 10 qualifying years on your record, and to get the full amount you need about 35 qualifying years. A qualifying year is one where you paid or were credited with enough National Insurance.
Beyond the State Pension, your record can affect entitlement to things like contribution based Jobseeker's Allowance, Employment and Support Allowance, Maternity Allowance and bereavement support. It does not fund the whole of the NHS, despite a common belief that it does. The money goes into a National Insurance Fund and general taxation, and the benefits above are the ones your personal record actually unlocks.
This is the point people miss. Income Tax buys you nothing personally. National Insurance builds an entitlement. That is the reason it can be worth paying even when you are not strictly forced to, which we come back to below.
The Four Classes of National Insurance
National Insurance is split into classes depending on how you earn. Most people only ever deal with one or two, but it helps to see the whole map:
- Class 1 is paid by employees, deducted from wages, with a separate employer contribution on top.
- Class 2 relates to the self employed and is now largely automatic rather than something you pay.
- Class 3 is voluntary, used to fill gaps in your record.
- Class 4 is paid by the self employed on their profits.
There used to be a Class 1A and 1B as well, which employers pay on benefits in kind such as company cars. If you are an employee that shows up on your P11D rather than on your payslip, and the rate is 15 percent for 2026/27.
Class 1: If You Are Employed
If you work for an employer, you pay Class 1 National Insurance, and it comes straight out of your pay through PAYE before you see it. For the 2026/27 tax year the employee rates are:
- Nothing on earnings up to the Primary Threshold of £12,570 a year, which is £242 a week.
- 8 percent on earnings between £12,570 and £50,270 a year, so between £242 and £967 a week.
- 2 percent on everything above £50,270 a year, above £967 a week.
Notice that the rate falls once you cross the higher threshold, which is the opposite of Income Tax. Someone earning a very high salary pays only 2 percent National Insurance on the top slice of it. The main employee rate was cut from 12 percent to 10 percent and then to 8 percent across 2024, so today's 8 percent is historically low.
Your employer pays their own Class 1 contribution too, at 15 percent on your earnings above £5,000 a year for 2026/27. That does not come off your payslip, but it is a real cost of employing you, and it is one reason wages and hiring decisions are so sensitive to National Insurance changes. The employer rate rose from 13.8 percent to 15 percent and the threshold dropped to £5,000 from April 2025, which raised the cost of employment noticeably for small businesses.
Class 4 and Class 2: If You Are Self Employed
If you run your own business as a sole trader, you pay National Insurance through Self Assessment rather than PAYE, and it is worked out on your profits, not your turnover. The main charge is Class 4, and for 2026/27 it works like this:
- Nothing on profits up to £12,570.
- 6 percent on profits between £12,570 and £50,270.
- 2 percent on profits above £50,270.
The Class 4 main rate was cut from 9 percent to 6 percent in April 2024, so the self employed pay a lower headline rate than employees on the same band. Class 4 is calculated automatically when you file your Self Assessment return and paid alongside your Income Tax.
Class 2 used to be a flat weekly charge for the self employed, but that changed. From April 2024, if your profits are above the Small Profits Threshold, which is £7,105 for 2026/27, your Class 2 is treated as paid without you handing over any money. You get the National Insurance credit for free. If your profits are below £7,105, you can still choose to pay Class 2 voluntarily at £3.65 a week to protect your record, and for many low earning self employed people that is a very cheap way to keep a qualifying year.
How Much National Insurance Will I Pay?
The quickest way to see it is with a figure. Take an employee earning £35,000 a year in 2026/27. They pay 8 percent on the slice above £12,570, which is £35,000 minus £12,570, so £22,430 taxed at 8 percent. That is about £1,794 of National Insurance for the year, roughly £150 a month, taken off before their pay lands.
A self employed person making the same £35,000 profit pays Class 4 at 6 percent on the same slice, so £22,430 at 6 percent is about £1,346 for the year, with no Class 2 to pay because their profit is above the Small Profits Threshold. The self employed person pays less National Insurance on identical earnings, though they lose some of the protections and paid time off that come with employment.
If you want a personal number rather than a worked example, our salary calculator breaks down Income Tax and National Insurance from your gross pay, which is more accurate than doing the bands in your head.
Voluntary Contributions and Filling Gaps
Because your State Pension depends on qualifying years, gaps in your record can quietly reduce what you eventually get. Gaps happen more often than people expect: years spent abroad, long periods of low self employed profit, time out of work without claiming benefits that carry credits, or a spell of low paid part time work below the threshold.
You can fill many of these gaps by paying voluntary Class 3 contributions, which cost £18.40 a week for 2026/27, or a full year's worth of about £957. That sounds like a lot until you compare it to the extra State Pension it can buy. One extra qualifying year can add over £300 a year to your pension for life, so the money often pays for itself within a few years of retirement. This is one of the few pieces of the tax system where paying more, voluntarily, can genuinely be the smart move.
You can normally only go back six years to fill gaps, so it is worth checking your record while you still can. You can see your National Insurance record and State Pension forecast through your Personal Tax Account on GOV.UK. Do not confuse any of this with your National Insurance number, which is just the reference that identifies you. The number never changes and paying it in is not the same as having a complete record.
National Insurance and Company Directors
If you run a limited company, National Insurance gets more interesting, because you can control how you take money out. A common approach is to pay yourself a modest salary through PAYE and take the rest as dividends, which do not attract National Insurance at all. Set the salary carefully and you can secure a qualifying year for your State Pension while keeping the National Insurance bill low.
Directors also have a quirk in how their Class 1 is calculated. Rather than working it out pay period by pay period, National Insurance for directors is assessed on an annual basis, which smooths out uneven pay across the year. This is one of several reasons director pay is worth setting up with an accountant rather than guessing, because the interaction between salary, dividends, corporation tax and National Insurance decides how much you actually keep.
Our View
National Insurance is the tax people understand least and check least, and that combination costs money. Employees rarely question the deduction on their payslip, the self employed often do not realise Class 2 changed, and almost nobody looks at their qualifying years until they are near retirement, by which point the six year window to fix gaps may have closed.
Our honest view is that National Insurance deserves an annual glance, the same way we say your tax code does. Check your State Pension forecast, look at whether you have any gap years, and if you are self employed on low profits, decide deliberately whether to pay voluntary Class 2 rather than letting the year lapse. These are small actions with a long payoff. The system is also politically live: rates have moved several times in the last few years, so what was true two years ago may not be true now, and it is worth checking the current figures rather than relying on memory.
How IAK Can Help
We deal with National Insurance every day, from the payroll side for employers to the Self Assessment side for the self employed. Our payroll service makes sure your employees' Class 1 is deducted correctly and your employer contributions are right, and our personal tax team handles Class 4 and Class 2 through your Self Assessment so nothing is missed or double counted.
If you are a company director, our tax planning service sets your salary and dividend split so your National Insurance works with your Income Tax and corporation tax rather than against them, and protects your qualifying years along the way. Not sure whether you even need an accountant for this? Contact us for a free consultation and we will tell you straight.
Sources
- National Insurance: introduction, GOV.UK, on what National Insurance is, the classes and who pays.
- National Insurance rates and categories, GOV.UK, on the 8 percent and 2 percent Class 1 employee rates, the 15 percent employer and Class 1A rates and the 2026/27 thresholds.
- Self-employed National Insurance rates, GOV.UK, on the Class 4 rates, the £7,105 Small Profits Threshold and the treatment of Class 2.
- Voluntary National Insurance, GOV.UK, on the £3.65 Class 2 and £18.40 Class 3 weekly voluntary rates for 2026/27.
- The new State Pension: your National Insurance record, GOV.UK, on the 10 year minimum and 35 year full entitlement qualifying years.