Calculator · Self-employed
Self Assessment estimator
Estimate the tax and NI you'll owe via Self Assessment, plus the payments on account due next January and July.
Tax year 2025/26
Calculator answer
Enter your figures to estimate the result for the 2025/26 tax year. The output is a planning estimate only and should be checked against HMRC guidance before filing or paying tax.
Estimated bill (31 January)
£8,748
- Income tax on self-employed profit
- £4,486
- Class 4 NI
- £1,346
- Less PAYE already paid
- −£0
- Balancing payment
- £5,832
- First payment on account (towards next year)
- £2,916
- Total to pay 31 January
- £8,748
- Second payment on account (31 July)
- £2,916
How this calculator works
If your self-employed profit is over £1,000 you must file a Self Assessment return. The deadline for online filing is 31 January following the end of the tax year (so 31 Jan 2027 for the 2025/26 year).
If your total bill is £1,000 or more, you'll also need to make payments on account — two instalments of 50% each, due 31 January and 31 July, towards next year's bill. That means your first January after going self-employed can be a nasty surprise: full bill + 50% on account = up to 150% of your liability in one payment.
Class 2 NI (£3.45/week) was removed in April 2024 for those with profits over the small profits threshold, but you can still pay it voluntarily to protect your state pension if you're below the threshold.