Your inputs
Estimated take-home from your self-employed profit
£0
After income tax, Class 4 NICs, and any student loan drag.
What this means
You have a straightforward profit profile here, so the main task is simply ring-fencing the tax reserve before it gets mixed into day-to-day cash flow.
Why is this based on profit, not turnover?
Self-employed tax is charged on profit after allowable business costs, not on revenue. Turnover tells you how much cash came in; profit is the number the tax system usually cares about.
Why do people get caught out by payments on account?
Once your Self Assessment bill is large enough, HMRC can ask for advance payments towards the following year as well. This calculator focuses on the underlying annual tax drag, so use the reserve figure as a minimum cash buffer rather than a promise about your exact January payment.
What about Class 2 National Insurance?
Since April 2024, most sole traders no longer pay mandatory Class 2 NICs, but small profits can still matter for your National Insurance record. If profits are very low, it can be worth checking whether voluntary Class 2 or another qualifying year route matters for State Pension purposes.
Worked examples — see the maths on real numbers
Two realistic profit scenarios showing how income tax and Class 4 National Insurance stack up for UK sole traders in 2026/27, and why no Class 2 is added.
Sarah — freelance copywriter, first full year
| Gross profit (income minus expenses) | £32,000 |
| Personal Allowance (2026/27) | £12,570 |
| Taxable profit | £19,430 |
| Other PAYE income | None |
The maths:
- Income tax: £19,430 × 20% = £3,886
- Class 4 NI: (£32,000 − £12,570) × 6% = £1,165.80
- Class 2 NI: nothing to pay. Her profit is above the £7,105 Small Profits Threshold, so Class 2 is treated as paid and the year still counts towards her State Pension
- Total tax + NI: £3,886 + £1,165.80 = £5,051.80, which the calculator shows as £5,052
Result: Sarah keeps about £26,948 after tax — an effective tax rate of 15.8% on her £32,000 profit. Her online Self Assessment return and payment for 2026/27 are due by 31 January 2028. Because the bill is over £1,000 and none of it was collected at source, a first payment on account for 2027/28 of half the bill (about £2,526) is due on the same date.
Marcus — IT consultant, higher-rate territory
| Gross profit | £72,000 |
| Personal Allowance | £12,570 |
| Taxable profit | £59,430 |
The maths:
- Basic-rate income tax: £37,700 × 20% = £7,540
- Higher-rate income tax: (£59,430 − £37,700) × 40% = £8,692
- Class 4 NI: (£50,270 − £12,570) × 6% + (£72,000 − £50,270) × 2% = £2,262 + £434.60 = £2,696.60
- Class 2 NI: nothing to pay; it is treated as paid because his profit is above the £7,105 Small Profits Threshold
- Total: £7,540 + £8,692 + £2,696.60 = £18,928.60, which the calculator shows as £18,929
Result: Marcus keeps about £53,071 after tax — effective rate 26.3%. His 2026/27 bill (less any payments on account already made towards it) is due by 31 January 2028. Because the bill is over £1,000, he also makes two payments on account towards 2027/28, each half of the 2026/27 income tax and Class 4 NI (about £9,464), due on 31 January 2028 and 31 July 2028.
Figures use 2026/27 UK tax-year rates and thresholds. Always verify against your specific payslip or tax statement before acting.
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