Self-Employed National Insurance Calculator

Self-Employed NI Guide 2026/27

What's the key thing to understand about Major Change: Class 2 Abolition?

April 2024 brought a significant change to self-employed NI: Class 2 NI abolished as a compulsory payment for those earning above the Small Profits Threshold (£6,725 for 2026/27). Previously: Class 2 was £3.45/week (£179.40/year) — mandatory if profits over £6,725. From April 2024: above £6,725 profits → no Class 2 owed but still get state pension credit. Below £6,725 profits → can pay Class 2 voluntarily (£3.45/week = £179.40/year) to maintain NI record. Why pay voluntary Class 2 if eligible? Because £179.40/year is far cheaper than losing a qualifying year toward the state pension, which would otherwise cost far more to buy back later or reduce your pension permanently.

What should I know about Class 4 NI Rates 2026/27?

Class 4 NI: paid by self-employed on annual profit. Reduced from April 2024: 6% on profits £12,570-£50,270 (was 9%). 2% on profits above £50,270 (unchanged). Worked examples 2026/27: £25,000 profit: (£25,000 - £12,570) × 6% = £746. £45,000 profit: (£45,000 - £12,570) × 6% = £1,946. £60,000 profit: (£50,270 - £12,570) × 6% + (£60,000 - £50,270) × 2% = £2,262 + £195 = £2,457. £100,000 profit: (£50,270 - £12,570) × 6% + (£100,000 - £50,270) × 2% = £2,262 + £995 = £3,257. Compare with employed: the same profit level as an employee typically incurs more combined employee NI and employer NI than a self-employed person pays in Class 4 alone, which is one of the tax advantages of self-employment.

What should I know about Class 4 Calculation Detail?

Class 4 NI applies to TRADING profits only, not other income. Includes: profit from self-employment trade. Profit share from partnerships. Profit from professional services. Excludes from Class 4: rental income (declared but no Class 4 NI). Capital gains. Dividend income. Investment income. Pension income. Interaction with employed income: if also employed (paying Class 1 NI through PAYE): Class 4 still applies on self-employed profits. No annual cap was removed years ago. Both NI types combine.

What's the key thing to understand about Voluntary Class 2 — When to Pay?

If your profits are BELOW £6,725: Class 2 NOT compulsory. You can pay £179.40/year voluntary Class 2 to maintain state pension qualifying year. Critical for: lower-income years (between paid employment, low-profit early business). Maternity/paternity time. Sabbatical years. Building toward 35 qualifying years (full new state pension). How much one year is 'worth' in state pension: each missing year reduces state pension by £6.32/week (£329/year) over your retirement. Over a 20-year retirement, that's roughly £6,580 in extra state pension for a one-off cost of £179.40 — a strong return that makes voluntary Class 2 worth paying if you have any gap years.

Why Self-Employed National Insurance Works Differently Than Employee NI

Employees pay Class 1 National Insurance through PAYE, calculated on a percentage basis against earnings within set bands. The self-employed instead pay Class 4 National Insurance, calculated on annual profits (not revenue) above a lower profits threshold, generally at a lower rate than employee Class 1 NI on earnings within the equivalent band — a long-standing difference partly justified by the fact that self-employed workers historically built up different, sometimes lesser, entitlement to certain contributory benefits than employees, though the gap in entitlement has narrowed over the years through reforms. Because Class 4 NI is based on annual profit after allowable business expenses, it rewards legitimate expense claims in the same way income tax does — reducing both taxes simultaneously for every pound of genuine deductible cost.

Why Voluntary Class 2 Contributions Can Still Matter for Your State Pension Record

Class 2 National Insurance was historically a small flat weekly contribution self-employed workers paid specifically to build qualifying years toward the State Pension and other contributory benefits, and reforms have changed how low-profit self-employed workers access those qualifying years, in some cases through voluntary contributions rather than a mandatory charge. For anyone with self-employment profits below the threshold where contributions are compulsory, it's worth actively checking whether a voluntary payment is needed to secure a qualifying year toward the State Pension — missing qualifying years, even in low-income years, can reduce the eventual State Pension amount, so this is a detail worth checking directly with HMRC or a pension forecast rather than assuming low profit automatically means no action is needed.

How NI Sits Alongside Income Tax on the Same Profits

<p>Self-employed National Insurance is not a separate system running in parallel to income tax — it is calculated on the same self-assessment tax return, using the same figure for taxable profit after allowable business expenses have been deducted. Income tax and Class 4 National Insurance are both applied to that one profit figure, just at different rates and with different thresholds, and both are paid together through the same self-assessment bill, typically by 31 January following the end of the tax year, alongside any payments on account due for the following year. This is a different experience from employment, where income tax and NI are deducted separately from each payslip in real time. It means a self-employed person needs to budget for both liabilities out of the same pot of profit, and a change that affects taxable profit — claiming more allowable expenses, for instance — reduces the income tax bill and the Class 4 NI bill simultaneously, since they share the same underlying base figure.</p>

Worked Example: Class 4 NI on £45,000 Profit

Class 4 National Insurance for the self-employed is charged on profit above a lower threshold, at a main rate up to an upper threshold and a smaller rate above that, broadly mirroring how employee Class 1 NI works but calculated annually rather than per pay period.

For a sole trader with £45,000 of taxable profit, Class 4 NI comes to roughly £1,946 for the year, charged entirely at the main rate since profit doesn't reach the upper threshold where the rate drops. This sits alongside income tax calculated separately on the same profit figure, so the combined tax-and-NI "marginal" bite on self-employment profit in the basic-rate band typically works out noticeably higher than the headline 20% basic income tax rate alone suggests, which surprises many newly self-employed people doing their first tax return after leaving salaried employment.

NI Sits Alongside Income Tax on the Same Profits

A common source of confusion for the newly self-employed is treating National Insurance and income tax as if they're calculated on different figures, when in fact both Class 4 NI and income tax are based on the same self-employment profit figure from the same tax return, just with different thresholds, rates, and purposes. Income tax funds general government spending and uses the personal allowance plus basic/higher/additional rate bands; National Insurance specifically funds entitlement to the State Pension and certain contributory benefits, and uses its own separate thresholds that don't line up exactly with the income tax bands. The practical effect is that profit between the NI lower threshold and the income tax personal allowance is NI-liable but tax-free, while profit above the personal allowance is liable for both simultaneously, and profit that crosses into higher-rate income tax territory is also still subject to Class 4 NI, just at the lower upper-threshold NI rate rather than the main rate. Because both are calculated and paid through the same Self Assessment return, with payments typically due by 31 January following the tax year end (and potentially split with payments on account for the following year), self-employed workers need to budget for the combined bite of both, not just the income tax portion, when setting aside money for their tax bill throughout the year.

NI Across Multiple Income Sources

Someone who is both employed and self-employed in the same tax year — for example, holding a part-time job alongside freelance work — pays Class 1 NI through PAYE on the employment income and Class 4 NI on the self-employment profit separately, each calculated against its own threshold rather than being combined into a single calculation first. This can occasionally lead to overpaying NI overall, since each income source's NI is assessed as if it were the person's only income, without necessarily accounting for the fact that the person has already used up much of the relevant threshold through the other source. HMRC provides an annual maximum NI contribution rule and a deferment or refund mechanism for exactly this situation — someone who expects to have both employed and self-employed income above the relevant thresholds in the same year can apply to defer part of their Class 4 NI liability in advance, or claim back any resulting overpayment after the tax year ends once both income sources are known in full. This is a commonly missed refund opportunity for people juggling a job and a side business, since neither PAYE nor Self Assessment automatically flags the overlap without the taxpayer specifically checking for it.