Quarterly profit
£9,000
Annualised profit (× 4)
£36,000
Estimated annual Income Tax
£4,686
Estimated annual Class 4 NI
£1,406
Set aside this quarter
£1,523
Effective combined rate: 16.9% on annualised profit
How the Calculation Works
We take your quarter's income minus expenses to get quarterly profit, then annualise it (× 4) so the correct UK tax bands apply. We then calculate Income Tax using 2025/26 bands (Personal Allowance £12,570, basic rate 20% to £50,270, higher rate 40% to £125,140, additional rate 45%), apply the £100k personal allowance taper, and add Class 4 National Insurance (6% main, 2% upper). The result is divided by four to give you a sensible amount to set aside per quarter.
This is an estimate to help you budget — final figures depend on your full tax position, including other income, pension contributions, Gift Aid and reliefs. Always confirm with your accountant before paying HMRC.