Taxes Management Act 1970 section 9

Returns to include self-assessment

Section 9 requires that personal and trustee tax returns include a self-assessment calculating the income tax and capital gains tax due, and sets out the circumstances in which HMRC will calculate the assessment on the taxpayer's behalf.

• Every personal or trustee tax return must include a self-assessment showing the income tax and capital gains tax chargeable for the year, together with the net income tax payable after deducting tax already withheld at source
• Certain taxes are excluded from self-assessment, including charges on pension scheme administrators, managers of qualifying recognised overseas pension schemes, sub-scheme administrators, and responsible persons for employer-financed retirement benefits schemes
• A taxpayer is not required to calculate their own self-assessment if they file their return by 31 October following the tax year, or within two months of receiving a notice to file where that notice is issued after 31 August following the tax year
• Where a taxpayer does not include a self-assessment, HMRC must (if the filing deadline applies) or may (in other cases) calculate the assessment on the taxpayer's behalf using the information in the return, and that assessment is then treated as a self-assessment forming part of the return