National Insurance for Sole Traders: Class 2 and Class 4 Explained

Unlike employed workers who pay Class 1 National Insurance through PAYE, sole traders pay two types of NI: Class 2 and Class 4. Both are calculated and collected through your Self Assessment tax return, so there is no separate payment process. Your National Insurance contributions fund your entitlement to certain state benefits, including the State Pension, Maternity Allowance, and bereavement benefits.\n\nClass 2 NI is a flat weekly rate that all self-employed people earning above the Small Profits Threshold pay. For the 2025/26 tax year, the Class 2 rate is 3.45 pounds per week, totalling approximately 179.40 pounds for the full year. The Small Profits Threshold is 6,725 pounds, meaning you only pay Class 2 if your self-employment profits exceed this amount.\n\nClass 4 NI is a percentage-based contribution calculated on your annual self-employment profits. It is charged at two rates: a main rate on profits between the Lower Profits Limit and the Upper Profits Limit, and a reduced rate on profits above the Upper Profits Limit. Unlike Class 2, Class 4 does not directly contribute to benefit entitlements but is a mandatory contribution alongside income tax.\n\nBoth classes are calculated automatically when you file your Self Assessment return. The amounts are added to your tax bill and collected together, either through your balancing payment or via payments on account if applicable. TradeTally shows your estimated NI liability alongside your income tax as you track your profits throughout the year.

Class 2 National Insurance is the contribution that builds your qualifying years for the State Pension. You need 35 qualifying years of NI contributions to receive the full new State Pension, which is currently 221.20 pounds per week for 2025/26. Each year of Class 2 contributions counts as a qualifying year, making it exceptionally good value at just 3.45 pounds per week.\n\nIf your self-employment profits are below the Small Profits Threshold of 6,725 pounds, you are not required to pay Class 2 NI but can choose to pay voluntarily to protect your State Pension entitlement. This is particularly relevant for tradespeople who are just starting out, working part-time, or having a quiet year. The voluntary payment is the same 3.45 pounds per week.\n\nClass 2 contributions also count towards Maternity Allowance, which is relevant if you or your partner may claim this benefit. To qualify for Maternity Allowance, you generally need to have paid Class 2 NI for at least 13 of the 66 weeks before the expected due date. For self-employed tradeswomen or partners of tradespeople, maintaining Class 2 payments is therefore important.\n\nThere have been periodic rumours about the abolition of Class 2 NI, which was previously announced and then reversed. As of the 2025/26 tax year, Class 2 remains in place. If it is eventually abolished, the government has indicated that self-employed people would retain their benefit entitlements through an alternative mechanism, but no firm details have been confirmed.

Class 4 National Insurance for the 2025/26 tax year is charged at 6 percent on self-employment profits between the Lower Profits Limit of 12,570 pounds and the Upper Profits Limit of 50,270 pounds. On profits above the Upper Profits Limit, the rate drops to 2 percent. These rates were reduced from 9 percent and 2 percent respectively as part of changes implemented from April 2024.\n\nTo illustrate, consider a self-employed electrician with taxable profits of 45,000 pounds. Their Class 4 NI would be 6 percent of the amount between 12,570 and 45,000 pounds, which equals 6 percent of 32,430 pounds, giving a Class 4 liability of 1,945.80 pounds. Add the Class 2 contribution of 179.40 pounds, and total NI for the year is 2,125.20 pounds.\n\nFor a higher-earning tradesperson with profits of 70,000 pounds, the calculation has two parts. The main rate of 6 percent applies to profits between 12,570 and 50,270 pounds (37,700 pounds), giving 2,262 pounds. The additional rate of 2 percent applies to profits between 50,270 and 70,000 pounds (19,730 pounds), giving 394.60 pounds. Total Class 4 NI is 2,656.60 pounds, plus Class 2 of 179.40 pounds, for a total NI bill of 2,836 pounds.\n\nClass 4 NI is collected through Self Assessment and included in your payments on account calculations. This means your January and July advance payments include an estimate for Class 4 NI based on the previous year's profits. TradeTally calculates both Class 2 and Class 4 contributions in real time as part of your running tax estimate.

Many tradespeople start their businesses while still employed, or take on employed work alongside their self-employment. If you are both employed and self-employed, you may pay Class 1 NI through your employer's payroll and Class 2 and Class 4 through Self Assessment. There are annual maximum contribution rules that prevent you from paying more than a certain total.\n\nThe annual maximum NI calculation is complex, but in practice HMRC handles it automatically through your Self Assessment return. If the combination of your Class 1 and Class 4 contributions exceeds the annual maximum, HMRC will reduce your Class 4 liability accordingly. You may receive a refund or credit if too much has been collected.\n\nClass 2 is always due on your self-employment profits regardless of your employment status, as long as your self-employment profits exceed the Small Profits Threshold. It is not affected by the annual maximum calculation because it is a flat-rate contribution.\n\nIf you are transitioning from employment to full self-employment, there may be a year where you have both types of income. Ensure you keep your employment records separate from your self-employment records in TradeTally to make your tax return straightforward and to ensure the NI calculations are correct.

If you have gaps in your National Insurance record from years when you did not work or earned below the thresholds, you can make voluntary contributions to fill those gaps and improve your State Pension entitlement. You can usually go back up to six years to fill gaps, though there are sometimes extended deadlines for older gaps.\n\nChecking your NI record is straightforward through the government's online service at gov.uk. Your record shows each tax year and whether it counts as a qualifying year, has gaps, or can be topped up with voluntary contributions. Before paying to fill any gaps, check how many qualifying years you already have and how many more you need for a full State Pension.\n\nVoluntary Class 2 contributions for past years are charged at the rate that applied during that year, making them significantly cheaper than voluntary Class 3 contributions, which are an alternative route to filling gaps at 17.45 pounds per week for 2025/26. However, voluntary Class 2 contributions are only available to people who were self-employed during the relevant tax year.\n\nFor tradespeople approaching retirement age, checking and filling NI gaps can be one of the most cost-effective financial decisions you make. Each additional qualifying year of the State Pension is worth approximately 328 pounds per year in retirement income, paid for life. Compared to the cost of voluntary Class 2 contributions at under 180 pounds per year, the return on investment is substantial.