How much should I put aside for tax?

This estimates income tax and Class 4 National Insurance for a sole trader in the 2026 to 2027 tax year, from 6 April 2026 to 5 April 2027. The rates are the ones on GOV.UK, linked below. I read them on 18 October 2026. This is an estimate, not tax advice. It does not file anything, and the figures stay in the browser.

It covers England, Wales and Northern Ireland, and Scotland if you tick the box. It is one self-employment profit. Employment, a pension, rent, savings and dividends are not in the sum. A limited company pays Corporation Tax, which is a different bill. The CIS deduction calculator is the sum on a single subcontract invoice.

The figures it uses

All of these were read from GOV.UK on 18 October 2026. If a page has moved on since then, the page wins.

• Personal Allowance

  £12,570. It goes down by £1 for every £2 of adjusted net income above £100,000, and it is zero from £125,140. Income Tax rates and Personal Allowances (opens in a new tab).

• England, Wales and Northern Ireland

  After the Personal Allowance: 20% up to £37,700, 40% from £37,701 to £125,140, and 45% over £125,140. With the standard allowance, that is 20% on income from £12,571 to £50,270. Income Tax rates and allowances for current and past years (opens in a new tab), updated 6 April 2026, and the current rates page (opens in a new tab).

• Scotland

  After the Personal Allowance: 19% up to £3,967, 20% from £3,968 to £16,956, 21% from £16,957 to £31,092, 42% from £31,093 to £62,430, 45% from £62,431 to £125,140, and 48% over £125,140. Income Tax in Scotland (opens in a new tab) shows the same bands with the £12,570 allowance added on.

• Class 4 and Class 2

  Class 4 is 6% on profits over £12,570 up to £50,270, and 2% on profits over £50,270. You only pay it if profits are more than £12,570. If profits are £7,105 or more, Class 2 is treated as paid and you do not pay it. Under that, voluntary Class 2 is £3.65 a week. Self-employed National Insurance rates (opens in a new tab). Class 4 is the same in Scotland.

The £1,000 trading allowance is on the income tax rates page. This calculator does not apply it. If you use it instead of expenses, put the profit in yourself. Blind Person's Allowance for 2026 to 2027 is £3,250 on the rates and allowances page. It is not added here.

Payments on account, in plain words

A payment on account is not a second tax bill for the same year. HMRC's payments on account page (opens in a new tab) says they are payments towards your next tax bill, including Class 4 if you are self-employed. Each one is usually half of the tax you owed last year. They are due by midnight on 31 January and midnight on 31 July.

You do not have to pay them if the tax you owed last year was less than £1,000, or if you paid more than 80% of that tax outside Self Assessment, for example through a tax code. The statement shows the figure if it applies.

This calculator does not add them. The monthly and weekly amounts are the tax and Class 4 on the profit you typed, minus CIS if you entered it. On a first return, January can be the whole bill plus the first payment towards the next year. On a steady year, the two payments on account are paying next year early, while last year's payments covered part of this year. The pounds on your own statement are the ones to use. I have written the January and July dates out in the payments on account guide.

CIS already taken is an advance towards this bill, not a payment on account. How a sole trader records it is in the CIS tax refund guide. What comes off before the profit exists is in the allowable expenses guide. The filing date for the 2025 to 2026 return is in the 31 January 2027 guide. Other free tools are on the tools page.