SelfSubmit is designed to help you stay compliant with HMRC Making Tax Digital requirements. You remain responsible for ensuring the information you submit is accurate.

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Tax Calculations

Tax due depends on total income, allowances, and reliefs — not only quarterly trading summaries. Plan cash flow around estimates and final calculations.

  • Income tax bands and personal allowance apply to total income
  • Payment on account based on prior year profit
  • Student loans and benefits charges may increase the bill

What it is

Tax is calculated on your total income minus allowances and reliefs. MTD quarterly updates do not always show your final tax bill; the final declaration determines tax due after all income is included.

Class 2 and Class 4 National Insurance apply to self-employed profits above thresholds. Dividend and savings allowances reduce tax on those sources separately. HMRC’s estimate tools help planning but are not professional advice.

Who it applies to

All Self Assessment taxpayers, including those on MTD.

What you need to do

  • Review HMRC’s tax calculation after submitting your final declaration.
  • Set aside money for tax and National Insurance throughout the year.
  • Use HMRC’s estimate tools for planning (not a substitute for professional advice).

Key points

  • Payment on account spreads next year’s bill based on previous years.
  • Student loans and Child Benefit charges may affect total due.

Common mistakes to avoid

  • Spending all profit without reserving tax money
  • Ignoring payment on account in July
  • Assuming CIS deductions mean no further tax is due

How SelfSubmit helps

SelfSubmit shows monthly net profit so you can set aside a sensible percentage for tax and NI throughout the year.

Further reading