How Much Should I Set Aside for Tax?
Estimate the Income Tax and Class 4 National Insurance generated by your self-employed profit, then turn it into a monthly or weekly savings target.
Your estimate
Enter annual figures excluding VAT
Total self-employed sales before expenses.
Do not include personal drawings or disallowed costs.
For example salary, pension, or rental profit before this business. Used for the Income Tax band only.
Suggested annual reserve
£9,212
About 19.2% of estimated business profit
Save monthly
£768
Save weekly
£177
Business profit
£48,000
Income Tax
£7,086
Class 4 NI
£2,126
Where the estimated profit goes
£38,788.20
£7,086.00
£2,125.80
Allow for possible payments on account
If payments on account apply and nothing has already been collected at source, a first 31 January payment could be around £13,818: the estimated bill plus 50% towards the following year. A further potential £4,606 would follow on 31 July. HMRC calculates the actual amounts after the return.
What This Estimate Includes
The calculator isolates the Income Tax created by the business profit and adds 2026/27 Class 4 National Insurance. It is a savings guide, not a Self Assessment computation.
Included
- 2026/27 Income Tax bands and Personal Allowance taper
- Scottish or rest-of-UK Income Tax selection
- Class 4 National Insurance at current thresholds and rates
Not included
- Student loans, pensions, benefits, Capital Gains Tax, or High Income Child Benefit Charge
- Tax already deducted, losses, overlap relief, basis-period adjustments, or special industry rules
- Class 2 voluntary contributions or VAT
Use it safely
- Update the estimate when sales, costs, or other income change
- Keep the reserve in a separate savings account where practical
- Check payments on account and the final liability against your HMRC statement
Need a precise Self Assessment forecast?
Find an accountant to review allowable expenses, other income, payments on account, and the filing position.