How Self-Employed NI Is Collected Through Self-Assessment

Self-employed national insurance is collected through the self-assessment tax return, with Class 4 contributions calculated automatically on your profits and paid alongside your income tax by 31 January each year. If you are a sole trader, you do not receive a separate national insurance bill: HMRC works out what you owe from the figures on your return and adds it to your overall liability. Understanding how national insurance for the self-employed in 2026 is charged, and when it falls due, helps you budget accurately and protect your entitlement to the state pension.

Blue Tick Accountants, a Guildford-based UK tax advisory and accountancy practice, works with sole traders across the UK to calculate contributions correctly and avoid surprises at the deadline. This article explains how Class 2 and Class 4 national insurance work in 2026/27, how each is collected, and what the rules mean for your state pension.

Key Takeaways

• Class 4 national insurance is charged at 6% on self-employed profits between £12,570 and £50,270 in 2026/27, and 2% on profits above £50,270.
• Class 2 national insurance is voluntary in 2026/27, but sole traders with profits at or above the £7,105 Small Profits Threshold are treated as having paid it and receive a qualifying year for the state pension at no cost.
• Sole traders with profits below £7,105 can pay voluntary Class 2 contributions at £3.65 per week to protect their national insurance record.
• Self-employed national insurance is collected through self-assessment and is due, with any income tax, by 31 January following the end of the tax year on 5 April.
• Thirty-five qualifying years of national insurance are needed for the full new state pension.

How is national insurance for the self-employed charged in 2026/27?

Self-employed individuals pay national insurance in two forms in 2026/27: Class 4 contributions based on profit, and Class 2 contributions that are now largely voluntary. Both classes are reported through the self-assessment tax return rather than through a separate demand from HMRC.

Class 4 is the main contribution most sole traders pay, calculated as a percentage of taxable profit so it rises and falls with your earnings. Class 2 previously operated as a flat weekly charge, but from April 2024 it stopped being compulsory for those meeting the profit threshold while still counting towards contributory benefits. Together these are known as self-employed NIC, and both are settled alongside your income tax liability.

For a full overview of how the system works, see our guide to National Insurance for the self-employed.

How much is Class 4 national insurance in 2026/27?

Class 4 national insurance is charged at 6% on profits between the Lower Profits Limit of £12,570 and the Upper Profits Limit of £50,270 in 2026/27, and at 2% on any profits above £50,270. There is no Class 4 charge on the first £12,570 of profit, which aligns with the personal allowance.

Consider a sole trader with taxable profit of £40,000 for 2026/27. Class 4 applies only to the profit above £12,570, so £27,430 is taxed at 6%, giving £1,645.80. A higher earner with £60,000 of profit pays 6% on the £37,700 up to £50,270 (£2,262.00) plus 2% on the £9,730 above it (£194.60), a total of £2,456.60. Both figures are added automatically to the income tax on the self-assessment calculation.

How does Class 2 national insurance work for sole traders now?

Class 2 national insurance is voluntary in 2026/27, but sole traders with profits at or above the Small Profits Threshold of £7,105 are treated as having paid it without any charge. This means that if your profits reach £7,105, you automatically build a qualifying year towards the state pension and other contributory benefits without paying the weekly rate.

Sole traders whose profits fall below £7,105 face a choice. They can pay voluntary Class 2 contributions at £3.65 per week, around £189.80 for a full year, to keep their record intact. This is often highly cost-effective, because a single qualifying year of state pension is usually worth far more over retirement than the modest contribution. Where you choose to pay, the amount is included in your self-assessment return and collected like Class 4.

When is self-employed national insurance paid to HMRC?

Self-employed national insurance is paid to HMRC through self-assessment and is due, together with any income tax, by 31 January following the end of the tax year on 5 April. For the 2026/27 tax year, the balancing payment deadline is 31 January 2028.

Class 4 contributions can also form part of your payments on account, the two advance instalments due on 31 January and 31 July, each based on the previous year's liability. Note that Making Tax Digital for Income Tax is now live: from 6 April 2026, sole traders and landlords with qualifying income above £50,000 must keep digital records and submit quarterly updates, with a final declaration due by 31 January. Those above £30,000 join from April 2027. National insurance is still calculated within the final declaration, so digital record-keeping does not change when payment falls due.

Frequently Asked Questions

Do self-employed people pay national insurance automatically?

No, self-employed national insurance is not deducted automatically like PAYE. Sole traders report their profits on a self-assessment tax return, and HMRC calculates the Class 4 and any Class 2 contributions due. The amount is added to the income tax liability and paid by 31 January following the tax year that ends on 5 April.

What is the difference between Class 2 and Class 4 national insurance?

Class 4 national insurance is a profit-based charge of 6% between £12,570 and £50,270, and 2% above, paid by most self-employed people in 2026/27. Class 2 is a flat contribution that is now voluntary; sole traders with profits at or above £7,105 receive its state pension benefit without paying, while those below can pay £3.65 per week.

Do I pay national insurance if I make a loss?

No, you do not pay Class 4 national insurance if your self-employment makes a loss or your profit is below £12,570 in 2026/27. However, if profits fall below the £7,105 Small Profits Threshold, you may want to pay voluntary Class 2 contributions at £3.65 per week to preserve a qualifying year towards your state pension.

How many qualifying years do I need for the full state pension?

You generally need 35 qualifying years of national insurance to receive the full new state pension, and at least 10 qualifying years to receive any new state pension at all. Self-employed profits at or above £7,105 in 2026/27 secure a qualifying year automatically, which is why protecting your record through voluntary contributions can be worthwhile in low-profit years.

How Blue Tick Can Help

Blue Tick Accountants helps sole traders calculate Class 2 and Class 4 national insurance correctly, decide whether voluntary contributions are worthwhile, and file a fully compliant self-assessment return under the new Making Tax Digital rules. Getting national insurance right protects both your cash flow and your future state pension entitlement. Head to our website and book a meeting now.

Conclusion

Self-employed national insurance in 2026/27 is straightforward once you know the structure: Class 4 at 6% and 2% on your profits, and Class 2 that is free above £7,105 but worth paying voluntarily below it. Because everything is collected through self-assessment by 31 January, the most important step is keeping accurate records and setting money aside. If your profits are low, check whether a voluntary contribution would protect a qualifying year before you file.

About the Author

This guide was written by Leon, founder of Blue Tick Accountants, a Guildford-based UK tax advisory and accountancy practice that helps self-employed people, landlords and limited company owners across the UK. It was last reviewed for the 2026/27 tax year.

This article is intended for general informational purposes only and does not constitute tax, legal, or financial advice. Tax rules are subject to change and their application will depend on your individual circumstances. You should always seek advice from a qualified professional before taking action. Blue Tick Accountants accepts no liability for decisions made on the basis of this content.