Taxes Consolidation Act 1997 section 959V

Amendment by chargeable person of return and of self assessment in return

Section 959V sets out the rules under which a chargeable person may amend a previously filed return and self assessment, including the permitted grounds for amendment, the method of notification, time limits, and restrictions where Revenue has commenced enquiries.

• A chargeable person may amend a filed return by notifying Revenue, but must amend the self assessment at the same time and state the specific ground for the amendment
• Notice must be given in writing to the relevant Revenue office, or electronically through ROS where the original return was filed electronically (except for capital gains tax amendments, which may still be made in paper form)
• An amendment must generally be notified within four years of the end of the chargeable period, subject to any shorter time limit applying to the particular relief or claim involved
• No amendment may be made once Revenue has started enquiries, an audit, or any other investigation relating to the return or self assessment for the chargeable period in question