Tax year

Where you live England Wales Northern Ireland Scotland

Income Tax bands differ in Scotland. Class 4 National Insurance is the same across the UK. Wales currently uses the same bands as England and Northern Ireland.

Turnover

Sales for the year, before expenses. Cash basis: money in. Traditional accounting: invoices.

Allowable expenses

What to deduct Allowable expenses £1,000 trading allowance

You cannot claim both. Expenses you type are treated as money spent either way. The comparison only changes which figure is deducted for tax.

Include voluntary Class 2 National Insurance if my profits are under the small profits threshold

Result

Enter a turnover. A worked example is on the button: £40,000 of sales and £10,000 of expenses, which is the shape of the example on GOV.UK's expenses guidance.

Assumptions

This profit is your only taxable income. A job, pension, savings or dividends would use the Personal Allowance and the bands first.
No pension contributions, Gift Aid, Marriage Allowance, Blind Person's Allowance or High Income Child Benefit Charge.
Adjusted net income, for the £100,000 Personal Allowance withdrawal, is treated as this profit.
Class 4 is not deducted before Income Tax is worked out. Class 2 is outside the tax calculation. From April 2024 it is not a compulsory charge once profits reach the small profits threshold.
The trading allowance replaces expenses. Class 4 is then charged on that lower profit. The National Insurance rates page describes profit as income minus expenses and does not repeat the allowance in its own words.
Student loan repayments are not included.
Self Assessment rounds income down to whole pounds. This page keeps pence, and rounds each band to the nearest penny. A real return can differ by pennies, or by about a pound.
From 2024/25 the cash basis is the default accounting method. Use the turnover and expenses that match the method you use. This page does not convert between them.
The voluntary Class 2 annual figure is the weekly rate times 52. GOV.UK does not publish the contribution-week count on the rates page. Some tax years have 53 weeks.

Sole trader take-home pay

Result

Assumptions

Sources on GOV.UK