Taxes Management Act 1970 section 9C

Amendment of self-assessment during enquiry to prevent loss of tax

Section 9C allows HMRC to amend a taxpayer's self-assessment during an open enquiry where they believe the tax stated is too low and there is a risk of tax being lost.

• Applies when an enquiry into a tax return is in progress following a notice of enquiry under section 9A(1)
• HMRC may amend the self-assessment by notice to the taxpayer if the tax stated is insufficient and immediate amendment is needed to prevent a loss of tax to the Crown
• Where the enquiry is limited to matters arising from a taxpayer's own amendment to the return, HMRC can only correct the deficiency to the extent it is attributable to that amendment
• The enquiry is treated as in progress from the date the notice of enquiry is given until a partial closure notice is issued for the matter in question, or a final closure notice is issued if no partial closure notice is given