UK Self Employed Tax Calculator

Calculate your Income Tax, Class 4 National Insurance, and Payments on Account for the 2026/2027 tax year.

Your Tax Breakdown

Total Tax & NI Due
£4,531.80
Income Tax
£3,486.00
Class 4 National Insurance
£1,045.80
Payments on Account (Each)
£2,265.90
Two payments towards next year's bill (due 31 Jan & 31 Jul)
Net Income
£25,468.20
Net
Tax
NI

About the Self Employed Tax Calculator UK

Calculate your self-employed tax and National Insurance bill for the 2026/27 UK tax year with our comprehensive and fully up-to-date Self Employed Tax Calculator UK. If you operate as a sole trader or are a self-employed professional in the UK, understanding exactly what you owe HMRC can be daunting, stressful, and mathematically complex. This advanced calculator is designed to precisely estimate your total Income Tax liability, your mandatory Class 4 National Insurance contributions, and, crucially, any required Payments on Account for the forthcoming tax year based entirely on your annual business profits. It fully incorporates the latest UK tax legislation, most notably reflecting the highly anticipated abolition of Class 2 National Insurance for the vast majority of self-employed individuals—a change that significantly simplifies the landscape but still leaves a challenging calculation. Navigating the UK tax system requires keeping track of varying personal allowances, shifting tax bands, and the often-surprising Payments on Account system. Whether you are newly self-employed and facing your very first Self Assessment tax return, or a seasoned business owner looking to forecast your cash flow and provision appropriately for upcoming HMRC bills, this tool delivers the clarity you need. It handles standard scenarios flawlessly while also managing complex edge cases such as the gradual tapering of the Personal Allowance for high earners whose profits exceed the critical £100,000 threshold. By providing immediate, transparent, and accurate estimates of your total tax and National Insurance obligations, this calculator empowers you to manage your finances with confidence, avoid unexpected shortfalls when the January 31st deadline approaches, and ensure you are fully prepared for both your balancing payment and your advance payments.

Mathematical Formula & Logic

The calculations underlying this tool strictly follow the official HMRC rules for the 2026/27 tax year and are broken down into three distinct, interconnected components: Income Tax, Class 4 National Insurance, and Payments on Account. First, your Income Tax is determined by applying the standard UK tax bands to your taxable profit. Your taxable profit is your total annual profit minus your Personal Allowance, which is currently set at £12,570. For the 2026/27 tax year, the basic rate of 20% applies to taxable profits up to £37,700 (which corresponds to total profits up to £50,270). The higher rate of 40% applies to taxable profits between £37,701 and £112,570 (corresponding to total profits between £50,271 and £125,140). Finally, the additional rate of 45% is levied on any taxable profits exceeding £112,570 (total profits above £125,140). It is vitally important to note the Personal Allowance taper: if your total profits exceed £100,000, your standard £12,570 Personal Allowance is reduced by exactly £1 for every £2 your profits sit above the £100,000 mark. Consequently, if your profits reach or exceed £125,140, your Personal Allowance is completely wiped out, falling strictly to zero. Second, Class 4 National Insurance is calculated entirely independently of Income Tax. For 2026/27, you pay a rate of 6% on any profits that fall strictly between the Lower Profits Limit of £12,570 and the Upper Profits Limit of £50,270. On any profits that exceed the £50,270 Upper Profits Limit, the Class 4 NI rate drops to exactly 2%. (Class 2 NI has been abolished for profits over £6,725). Finally, the system evaluates your requirement for Payments on Account. If your combined total bill for Income Tax and Class 4 NI is strictly greater than £1,000, and you do not have more than 80% of your tax deducted at source (such as through a concurrent PAYE job), you are legally obligated to make two Payments on Account towards your subsequent year's estimated bill. Each of these advance payments is calculated as exactly 50% of your total current year tax and NI liability.

Step-by-Step Example

To fully illustrate how these interconnected formulas function in practice, let us examine two highly detailed, contrasting scenarios based on the 2026/27 rules. Scenario 1: A Basic Rate Taxpayer. Imagine Sarah, a freelance graphic designer, who generated exactly £30,000 in annual business profits. First, we calculate her Income Tax. We deduct her standard Personal Allowance of £12,570 from her £30,000 profits, leaving a taxable profit of £17,430. Since this entire amount falls comfortably within the basic rate band, it is taxed at 20%. Therefore, her Income Tax is exactly £3,486. Next, we determine her Class 4 National Insurance. Her profits are above the £12,570 threshold but well below the £50,270 upper limit, so we apply the 6% rate to the profits falling between these two figures (which is £30,000 minus £12,570, equaling £17,430). 6% of £17,430 equals £1,045.80. Sarah's total tax and NI bill is the sum of these two figures: £3,486 plus £1,045.80 equals £4,531.80. Because this total liability is significantly greater than the £1,000 threshold, Sarah is legally required to make Payments on Account for the following tax year. She must make two advance payments, each equal to exactly 50% of her £4,531.80 bill, which equates to £2,265.90 per payment. Therefore, by January 31st, she must pay her current bill of £4,531.80 plus her first Payment on Account of £2,265.90, making a total required payment of £6,797.70. Scenario 2: A Higher Rate Taxpayer. Consider David, an IT consultant whose business profits for the year are exactly £60,000. For his Income Tax, his £12,570 Personal Allowance remains fully intact as he is below the £100,000 taper threshold. His taxable profit is £60,000 minus £12,570, which is £47,430. The first £37,700 of this is taxed at the basic 20% rate, resulting in £7,540. The remaining £9,730 of his taxable profit falls into the higher rate band and is taxed at 40%, generating £3,892. David's total Income Tax is £7,540 plus £3,892, equaling £11,432. For his Class 4 NI, he pays 6% on the maximum band between £12,570 and £50,270 (£37,700 in total), which comes to £2,262. He then pays 2% on his remaining profits above £50,270 (£60,000 minus £50,270 equals £9,730). 2% of £9,730 is £194.60. His total Class 4 NI is £2,262 plus £194.60, equaling £2,456.60. David's total combined tax and NI liability is £11,432 plus £2,456.60, which equals £13,888.60. He must also make two Payments on Account of £6,944.30 each.

Reference Data & Values

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Profits: £12,570 (Personal Allowance limit)Total Bill: £0 (No tax or NI due)
Profits: £30,000 (Basic rate)Total Bill: £4,531.80 (Plus £2,265.90 Payments on Account)
Profits: £50,270 (Higher rate threshold)Total Bill: £9,802.00 (Plus £4,901.00 Payments on Account)
Profits: £60,000 (Higher rate)Total Bill: £13,888.60 (Plus £6,944.30 Payments on Account)
Profits: £100,000 (Taper threshold)Total Bill: £30,688.60 (Plus £15,344.30 Payments on Account)
Profits: £125,140 (Zero allowance)Total Bill: £46,275.40 (Plus £23,137.70 Payments on Account)
Profits: £150,000 (Additional rate)Total Bill: £57,959.60 (Plus £28,979.80 Payments on Account)

Frequently Asked Questions

No, Class 2 National Insurance has been effectively abolished for the vast majority of self-employed people whose profits exceed £6,725. You now solely pay Class 4 National Insurance on your qualifying profits, which significantly simplifies your Self Assessment calculation.
If your total Self Assessment tax bill exceeds the statutory £1,000 threshold, you must generally make two advance Payments on Account for the next tax year. The first payment is due by midnight on 31 January (the exact same day as your balancing payment for the previous year) and the second is due by midnight on 31 July.
Each individual Payment on Account is calculated as exactly 50% of your total combined tax and National Insurance bill for the previous tax year. Together, these two payments are designed by HMRC to cover your expected tax liability for the upcoming year in advance.
The standard, default Personal Allowance for the 2026/27 UK tax year is precisely £12,570. You do not pay any Income Tax on your self-employment profits up to this specific amount. However, it is crucial to note that this allowance is progressively reduced if your overall profits are exceptionally high.
If your total self-employment profits exceed the critical £100,000 threshold, your standard Personal Allowance is legally reduced by exactly £1 for every £2 that your profits exceed £100,000. Consequently, this means if your profits reach or exceed £125,140, your Personal Allowance is completely eliminated and becomes zero.
You are legally required to start paying Class 4 National Insurance when your annual self-employment profits exceed the official Lower Profits Limit, which is strictly set at £12,570 for the 2026/27 tax year. You pay a rate of 6% on any profits falling strictly between this limit and the Upper Profits Limit of £50,270.
For any self-employment profits generated strictly above the Upper Profits Limit of £50,270 in the 2026/27 tax year, the Class 4 National Insurance rate substantially drops to exactly 2%. You still, however, pay the standard 6% rate on the specific portion of your profits sitting between £12,570 and £50,270.
No. If your annual self-employment profits are exactly £12,570, they are entirely and completely covered by the standard statutory Personal Allowance. In this exact, specific edge case, your total Income Tax liability will be strictly £0, and similarly, your Class 4 National Insurance liability will also be exactly £0.