Indietax

Class 4 NI Calculator — Self-Employed 2026/27

Updated for the 2026/27tax year · Last updated

Class 4 National Insurance is the profit-based NI charge paid by the self-employed. For 2026/27 the rate is 6% on profits between £12,570 and £50,270, then 2% above. Unlike Class 2, Class 4 gives you no benefit entitlement — it's purely a contribution to the tax system based on what you earn.

This calculator shows your Class 4 NIC broken down by band, so you know exactly what you owe alongside your income tax.

Net profit after allowable expenses — the figure you report on Self Assessment

BandRate
Up to £12,570.000%
£12,570.00 – £50,270.006%
Above £50,270.002%

Enter your annual profits above.

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How this calculator works

Lower Profits Limit (£12,570)

Class 4 NIC starts at £12,570 — the same as the income tax Personal Allowance. Profits below this threshold are completely NIC-free. This alignment means your first slice of self-employment income is effectively free of both income tax and NIC.

Main band: 6% on profits from £12,570 to £50,270

The main Class 4 rate of 6% applies to profits between the Lower Profits Limit (£12,570) and the Upper Profits Limit (£50,270) — a band of £37,700. The rate was reduced from 9% to 6% from 6 April 2024.

Upper band: 2% on profits above £50,270

Once your profits exceed £50,270, the rate drops sharply to 2% — the same reduced rate as Class 1 NIC for higher earners. There's no ceiling on this charge; profits of £100,000, £200,000 and beyond still attract the 2% rate.

How Class 4 fits alongside income tax

For a self-employed sole trader, your total liability on profits is income tax plus Class 4 NIC. At profits of £30,000, for example, you're paying 20% income tax plus 6% Class 4 — an effective combined marginal rate of 26% on profits between the Personal Allowance and the basic rate ceiling. Use the Income Tax Calculator to see your full income tax breakdown alongside this figure.

Class 2 summary

This calculator also shows your Class 2 position. For 2026/27, if your profits are £12,570 or more, Class 2 is treated as paid at no cost. For a detailed breakdown of Class 2 credits and voluntary contributions, see the Class 2 NI Calculator.

Payments on account

If your combined income tax and Class 4 NIC bill is £1,000 or more, HMRC requires advance payments in January and July. Use the Payment on Account Calculator to see how much you'll need to set aside and when the payments fall due.

Frequently asked questions

Class 4 NIC is the profit-based National Insurance charge paid by the self-employed. For 2026/27 you pay 6% on profits between £12,570 (the Lower Profits Limit) and £50,270 (the Upper Profits Limit), then 2% on any profits above £50,270. Unlike Class 2, Class 4 does not build any benefit entitlement — it is purely a tax on self-employment profits.
Class 2 was a flat weekly charge (now effectively abolished for most people) that built your NIC record for the State Pension and contributory benefits. Class 4 is a percentage-based charge on your profits — it raises revenue but gives you no entitlement to any benefit in return. For 2026/27, if your profits are above £12,570, you'll only have Class 4 NIC to pay (Class 2 is treated as paid automatically at no cost).
Class 4 NIC is collected through Self Assessment, not through payroll. You calculate and pay it alongside your income tax when you file your tax return. The payment deadline is 31 January following the end of the tax year — so for 2026/27, Class 4 NIC is due by 31 January 2028. It may also be included in your payments on account if your total bill is £1,000 or more.
No. Class 4 NIC only applies to net self-employed trading profits. Dividends from a limited company are subject to dividend tax, not NIC. If you run a limited company and pay yourself a combination of salary and dividends, only the salary is subject to Class 1 NIC (employer and employee). This is one reason why the limited company structure can be tax-efficient at higher profit levels.
Class 4 NIC is calculated automatically by HMRC when you file your Self Assessment return (or by your accountant or tax software). It is paid as part of your overall Self Assessment payment — there's no separate form or payment route. The amount due is included in your 31 January payment alongside income tax and any Class 2 contributions.
There are limited reliefs. Losses from one year can be carried forward and set against future profits, reducing the profits subject to Class 4. Pension contributions reduce your income tax bill but do not reduce Class 4 NIC — it's calculated on net profit before pension deductions. If you're over State Pension age, you are exempt from Class 4 NIC entirely.
If you're also employed, you may end up overpaying NIC across Class 1 and Class 4 combined. HMRC operates a "deferment" and annual maximum NIC calculation to prevent this. If you've paid more than the annual maximum across all classes, you can claim a refund after the end of the tax year. Your Self Assessment return triggers this automatically if the system has enough information.
The Lower Profits Limit is £12,570 for 2026/27 — aligned with the Personal Allowance. You pay Class 4 NIC at 6% on profits between £12,570 and £50,270, then 2% above £50,270 (the Upper Profits Limit). Profits up to £12,570 attract no Class 4 NIC.

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