National Insurance for the self-employed in the UK
Self-employed National Insurance is two contributions with different logic. Class 4 is a percentage of profit and is compulsory. Class 2 is a flat weekly amount that is now voluntary — and paying it deliberately is sometimes the best-value contribution in the system.
Class 4: the compulsory one
Both classes are charged under the Social Security Contributions and Benefits Act 1992, and both are collected through Self Assessment rather than separately.
| Profit band 2026/27 | Class 4 rate |
|---|---|
| Up to £12,570 (lower profits limit) | Nil |
| £12,570 – £50,270 | 6% |
| Over £50,270 (upper profits limit) | 2% |
The structure is unusual: the rate falls from 6% to 2% at £50,270, the same point at which income tax rises from 20% to 40%. The lower profits limit is aligned with the personal allowance at £12,570 and the upper profits limit is held at £50,270; both are maintained until 5 April 2031.
A worked calculation
Take a sole trader with taxable profit of £60,000.
| Slice | Amount | Rate | Class 4 |
|---|---|---|---|
| Up to £12,570 | £12,570 | 0% | £0 |
| £12,570 to £50,270 | £37,700 | 6% | £2,262 |
| Above £50,270 | £9,730 | 2% | £195 |
| Total Class 4 | £2,457 |
Watch the combined marginal position. At £49,000 of profit the next pound costs 40p — 20% income tax plus 6% Class 4, then 40% plus 2% once past £50,270. The combined marginal rate is 26% just below the limit and 42% just above it, so the jump at £50,270 is 16 points, not the 20 that looking at income tax alone suggests.
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Avail our UK tax desk servicesClass 2: voluntary, and often worth paying
| Item | 2026/27 |
|---|---|
| Class 2 weekly rate | £3.65 |
| Annual cost (52 weeks) | £189.80 |
| Small profits threshold | £7,105 |
| Class 3 voluntary weekly rate | £18.40 |
A self-employed person with profits below £7,105 can choose to pay Class 2 to keep a qualifying year for contributory benefits including the State Pension. At £189.80 for the year against Class 3 at £18.40 a week — £956.80 for the same qualifying year — Class 2 buys the identical outcome for about a fifth of the price.
The trap is timing. A low-profit year passes unnoticed, the qualifying year is lost, and topping it up later means Class 3 at five times the cost. Anyone with a genuinely low-profit year should decide on Class 2 in that year, not when they next look at their pension forecast.
Two changes took effect from 6 April 2026: individuals working outside the UK can no longer pay Class 2 voluntarily, and new applications for periods abroad require either ten consecutive years of UK residence or ten years of UK contributions.
How this compares with employment
| Self-employed | Employee | |
|---|---|---|
| Main rate | 6% (Class 4) | 8% (Class 1) |
| Upper rate | 2% | 2% |
| Employer contribution | None | 15% over £96/week |
| Collected via | Self Assessment | PAYE each pay period |
Self-employment carries a lower personal rate and no employer contribution, which is most of the reason engagers prefer contractors and HMRC scrutinises status. It also means nothing is withheld: the whole liability lands with the 31 January balancing payment.
Why the 6% looks unfamiliar
The main Class 4 rate has moved twice in recent years, which is why older guidance and older spreadsheets disagree with each other.
| Period | Main Class 4 rate |
|---|---|
| To 2021/22 | 9% |
| 2023/24 | 9% |
| 2024/25 | 6% |
| 2026/27 | 6% |
On £50,270 of profit the difference between 9% and 6% is £1,131 a year, so a template built before 2024/25 overstates the liability by roughly that amount at the upper limit. Check which rate any inherited calculator is using before trusting its output.
When you actually pay it
Both classes are collected through Self Assessment, not separately. Class 4 for 2026/27 is due with the balancing payment on 31 January 2028, and it is included in the payments on account calculation — which is why a first profitable year produces a January bill larger than the year's tax alone.
Where this goes wrong
- Budgeting income tax and forgetting Class 4 — on £60,000 of profit that is £2,457 unbudgeted.
- Letting a low-profit year lapse instead of paying £189.80 of Class 2, then facing Class 3 at £956.80.
- Assuming Class 2 is still available for periods working abroad. It is not, from 6 April 2026.
- Reading the 2% band as a discount. It applies only above £50,270, where income tax is 40%.
Related: sole trader versus limited company and registering for Self Assessment.
Sources
This guide is written against the official and clearly labelled professional references below. Rates, thresholds and portal procedures change between reviews, so open the primary source before relying on a figure.
Questions people also ask
How is self-employed National Insurance collected?
Through Self Assessment alongside income tax, rather than separately. It appears in the same calculation and is paid on the same dates, which is why people often do not notice it as a distinct charge.
Why do contributions matter beyond the current year?
They build entitlement to the State Pension and certain benefits, counted in qualifying years. Gaps in the record reduce entitlement decades later, long after the year in question is forgotten.
Can I fill gaps in my record?
Voluntary contributions can often fill past gaps, subject to time limits that are strict. Check your record early, because the window to correct an old year closes.
Does National Insurance apply to my Pakistani rental income?
National Insurance applies to earnings from work, not generally to property income. Rental income is subject to income tax but sits outside the self-employed contribution classes.
What if I am also employed?
You may pay contributions through both employment and self-employment, with annual maximum rules limiting the total. Check whether you have overpaid across the two sources.
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