UK self-employed National Insurance calculator

Work out Class 4 and Class 2 National Insurance on self-employed profits using dated GOV.UK and HMRC thresholds and rates for 2026/27 and 2025/26.

Your inputs

Valid for United Kingdom tax year 2026/27 (6 April 2026 to 5 April 2027). Source: official GOV.UK and HMRC pages, linked below. Reviewed on 18 October 2026. It covers a person who is self-employed only. Choose the previous tax year to see its figures instead. Estimate, not advice.

Tax year

Each tax year has its own dated figures, shown on this page with a review date. Pick the previous year to compare.

Profits from self-employment for the year (£)

Your self-employed income less allowable expenses. For a partnership, your share of the profits.

If profits are below the Small Profits Threshold

Class 2 is treated as paid when profits reach £7,105 (2026/27). Below that you can pay it voluntarily to protect your National Insurance record. It is shown for 52 weeks.

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A clear answer. Here’s how.

Class 4 is 6% of profits between the Lower Profits Limit (£12,570) and the Upper Profits Limit (£50,270) and 2% of profits above that, for 2026/27. Class 2 is no longer a charge for most people: when profits are at least the Small Profits Threshold (£7,105) it is treated as paid, and below it you can choose to pay £3.65 a week. The limits and rates come from the dataset for the tax year you choose, and the calculator refuses to run if no dataset covers today’s date. The Class 4 method (rate times profits between the limits, with nothing above the Upper Profits Limit at the old maximum) is tested against HMRC’s own worked examples from the National Insurance Manual.

What this does not include

Being employed as well as self-employed. Class 1 contributions through payroll interact with Class 4 (there is an annual maximum), so the tool is for people whose only work is self-employment.
Special cases: share fishermen and volunteer development workers (different Class 2 rates), examiners and invigilators (Special Class 4), landlords, ministers of religion, people who make investments, and people deferring National Insurance.
Income Tax on the same profits, the Personal Allowance, the trading allowance and student loan repayments.
Rounding in Self Assessment. The tool shows the result to the penny; HMRC’s return works to its own rounding rules.
Your age or circumstances, such as reaching State Pension age, and Class 3 voluntary contributions to fill gaps.
Class 2 beyond the voluntary case: the tool shows 52 weeks of voluntary payments, and the cost HMRC asks for can differ by the weeks you need to cover.
No HMRC worked example exists at the 2025/26 or 2026/27 rates; the figures were checked by hand against the published limits and rates, and the method against HMRC’s older examples.

How this is checked

3 reference checks passed These 3 cases were run when this page was built, on 20 October 2026, and all reproduce within the stated tolerance. The same cases are part of the automated tests that run on every change to Toolmoz. Engine version 1.

See the checks and where each expected answer comes from

Case 1
Inputs
Tax year 2026-27Profits from self-employment for the year (£) 30000If profits are below the Small Profits Threshold no
Expected, and what Toolmoz gave
Class 4 National Insurance expected 1045.8, Toolmoz 1045.8Class 2 to pay expected 0, Toolmoz 0Total self-employed National Insurance expected 1045.8, Toolmoz 1045.8
Where the expected answer comes from
GOV.UK: Self-employed National Insurance rates
Allowed difference
±0.005
Case 2
Inputs
Tax year 2025-26Profits from self-employment for the year (£) 60000If profits are below the Small Profits Threshold no
Expected, and what Toolmoz gave
Class 4 at the main rate expected 2262, Toolmoz 2262Class 4 at the upper rate expected 194.6, Toolmoz 194.6Total self-employed National Insurance expected 2456.6, Toolmoz 2456.6
Where the expected answer comes from
HMRC: Rates and allowances, National Insurance contributions (section 3, Class 2 and Class 4)
Allowed difference
±0.005
Case 3
Inputs
Tax year 2026-27Profits from self-employment for the year (£) 5000If profits are below the Small Profits Threshold yes
Expected, and what Toolmoz gave
Class 4 National Insurance expected 0, Toolmoz 0Class 2 to pay expected 189.8, Toolmoz 189.8
Where the expected answer comes from
GOV.UK: Self-employed National Insurance rates
Allowed difference
±0.005

What this shows: the engine reproduces independently worked values for these cases. It does not prove every possible input is right. To test an answer you were given, see how to check a number; to see what is and is not checked across Toolmoz, see the accuracy ledger.

See a worked example

Worked example

A fixed demonstration, separate from the values you enter above.

Tax year: 2026/27 (6 April 2026 to 5 April 2027)
Profits from self-employment for the year (£): 30000
If profits are below the Small Profits Threshold: Do not pay voluntary Class 2

Example result

Example result
Contribution	Profits in band (£)	Rate	Amount (£)
Class 4 on profits between £12,570 and £50,270	17,430	6%	1,045.8
Class 4 on profits over £50,270	0	2%	0
Class 2 (treated as paid; profits are £7,105 or more)			0
Total self-employed National Insurance			1,045.8

Valid for United Kingdom tax year 2026/27 (6 April 2026 to 5 April 2027). Source: official GOV.UK and HMRC pages, linked below. Reviewed on 18 October 2026. These are the rules in force today. Profits are your self-employed income less allowable expenses. Class 2 is shown for 52 weeks when you choose voluntary payments below the Small Profits Threshold of £7,105. Estimate only, not tax, legal or financial advice: see what is not included below.