Employed and Self-Employed Tax Calculator, 2026/27

How this is calculated

Income tax is worked out on your total income from both employment and self-employment combined, since you only have one personal allowance and one set of tax bands however many sources of income you have. Basic, higher and additional rate bands apply to the combined total, not separately to each source.

National Insurance is different: employee National Insurance is charged only on your salary, at 8.0% between the primary threshold and the upper earnings limit and 2% above it, while Class 4 National Insurance on self-employed profit uses the same annual thresholds but effectively starts from wherever your salary has already used up the threshold.

The calculator adds salary and profit together for the income tax calculation, then applies employee National Insurance to the salary alone and Class 4 National Insurance to the profit, taking account of the National Insurance thresholds already used by the salary.

Why this trips people up

Someone with a full-time job and a profitable side business often assumes their side income will be taxed at a low rate because it is small on its own, but because it stacks on top of salary for income tax purposes, it is frequently taxed at the higher rate rather than the basic rate.

This combined position also affects payments on account for the following year, since HMRC bases these on the self-employment element of your total self-assessment liability, which can catch people off guard the first year they file.

Planning points

Registering for self-assessment and setting aside tax from self-employed income as it is earned, rather than waiting until the following January, avoids a large unexpected bill once the two income sources are combined.

Pension contributions, whether through the employer's scheme or personally, reduce the combined taxable income and can be a useful way of managing which tax band the self-employed profit effectively falls into.

Do I pay tax twice if I have a job and a side business?

No, but the two incomes are added together for income tax purposes and taxed as one total using the normal bands, so your side income is often taxed at your marginal rate rather than a fresh basic rate allowance.

Do I still get a personal allowance for my self-employment?

No, you only get one personal allowance in total, which is typically used against your salary first, meaning most or all of your self-employed profit is taxable if your salary already exceeds the allowance.

Do I pay both employee National Insurance and Class 4?

Yes, employee National Insurance applies to your salary through PAYE, and Class 4 National Insurance applies separately to your self-employed profits, calculated using the combined thresholds across both sources.

Do I need to register for self-assessment?

Yes, if you have self-employed income alongside your job you need to register for self-assessment and report both your employment income and your self-employed profit on the same tax return each year.