National Insurance is the quiet line on every payslip that shapes your State Pension. Here is what it actually means for your money.
Most people notice National Insurance only when it takes a chunk from their pay, then promptly forget about it. That is a shame, because every year you pay NI and it counts as a 'qualifying year' brings you closer to the full new State Pension, currently £221.20 a week in 2025/26. Miss enough years and you retire on less. Pay in 35 qualifying years and you get the full amount. The stakes are higher than the small print suggests.
Unlike Income Tax, which applies in a single, progressive structure, National Insurance splits into several 'Classes' depending on how you earn your money. The Class you pay determines what benefits you can access and whether a year counts toward your State Pension.
| Class | Who Pays It | 2025/26 Rate | What It Covers |
|---|---|---|---|
| Class 1 (employee) | Employees on PAYE | 8% (£12,570–£50,270); 2% above £50,270 | State Pension, Jobseeker's Allowance, Maternity Allowance |
| Class 1 (employer) | Employers | 15% above £5,000 secondary threshold | Employer cost; no benefit to employee |
| Class 2 | Self-employed (voluntary) | £3.45/week (effectively treated as paid via SA) | State Pension, Maternity Allowance |
| Class 4 | Self-employed profits | 6% (£12,570–£50,270); 2% above £50,270 | No direct benefit; a profit-based tax |
| Class 3 | Voluntary top-ups | £17.45/week | Fill gaps in NI record |
If you are on PAYE, Class 1 is deducted automatically before your salary hits your bank. If you run your own business, you calculate and pay Class 4 (and voluntary Class 2) through your Self Assessment tax return each January.
The numbers become real when you run them against a specific salary or profit figure.
Your NI is calculated only on the band between the Primary Threshold (£12,570) and your earnings.
Want to check your own numbers? The TapTax salary tax calculator works out your Income Tax and NI side by side for any PAYE salary.
Self-employed profits are taxed differently to a salary. The TapTax sole trader tax calculator lets you model your total bill, Income Tax plus NI, in one go.
This is where the confusion usually starts. Both Income Tax and NI kick in at £12,570 in 2025/26, so many people assume they are effectively one tax. They are not. Income Tax is calculated on total taxable income including savings and dividends. NI is calculated only on employment income or self-employment profits. Company dividends, rental income and interest do not attract NI at all. That is one reason property landlords and limited company directors who pay themselves mostly in dividends face a very different NI bill to a sole trader on the same total income.
There is a second difference worth knowing: the 60% effective tax trap that squeezes earners between £100,000 and £125,140 (where the Personal Allowance is withdrawn at £1 for every £2 over £100,000) does not involve NI at all. Above £50,270, NI drops to just 2% while Income Tax climbs to 40%. The marginal rate mismatch is a genuine quirk of the UK system.
Every year that counts as a 'qualifying year' is one step toward the full new State Pension. A qualifying year simply means you earned above the Lower Earnings Limit (£6,396 in 2025/26) or paid voluntary contributions for that year. You can check your NI record and forecast through the HMRC personal tax account.
If you have gaps, perhaps from time abroad, a career break, or low-income years, you can pay voluntary Class 3 contributions to fill them. The current rate is £17.45 a week, or roughly £907 a year. A single qualifying year bought now could add £6.32 a week to your State Pension for the rest of your retirement. Over a 20-year retirement that is £6,573 from a £907 outlay. The window to fill gaps going back to 2006 extended to April 2025, so if you have not reviewed your record, that deadline has now passed for older gaps and the standard six-year window applies.
For more on how NI interacts with wider self-employment tax planning, the TapTax blog covers seasonal topics like the January Self Assessment deadline and how NI changes ripple into take-home pay.
When an employer pays you £40,000, their actual payroll cost is noticeably higher. From April 2025 the employer NI rate rose to 15%, applied to salary above a reduced secondary threshold of £5,000. On a £40,000 salary that means the employer pays:
This does not come out of your pay, but it shapes how employers think about total compensation and why many businesses consider alternatives like pension contributions (which reduce their NI liability) when structuring pay packages.
National Insurance is really two taxes in one: a levy on your current earnings and an investment in your future State Pension. Treat it as both.
TapTax connects to your bank, categorises expenses automatically, and submits quarterly updates to HMRC. Free plan, no card required.
