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HMRC internal manual

Company Taxation Manual

CTSA: the filing obligation: amended returns

The rules for CTSA periods and CTPF periods are different.

Under FA98/SCH18/PARA3 a company can amend information originally entered in its return and make corresponding amendments to its SA.

Under FA98/SCH18/PARA15 it can amend the return at any time up to twelve months from the statutory filing date.

When it makes a return for a wrong period the time allowed for making an amendment is twelve months from what would be the filing date if the period for which it made the return was an accounting period.

A company must make an amendment by notice to the Revenue. The notice must:

  • be in such form,


  • contain such information,


  • be accompanied by such statements,

as the Revenue may reasonably require.

Currently, the Revenue does not propose:

  • to prescribe the form and content of an amended return,


  • to provide an official form for amended returns.

Instead, companies and their agents can amend company tax returns informally, in correspondence.

If a company is in a simplified arrangement for group relief purposes (see CTM97000 onwards.), and the amendment to its return will lead to a change in group relief, then the joint amended return must include an amended SA for that company. The difference between CTPF and CTSA is that a return or amended return must include a self-assessment. This is in contrast to the position under CTPF for which SP9/93 previously set out the requirements of the Revenue.

When a company amends its return (unless the original is under enquiry or you want to open an enquiry into the amended return) you simply record the amendment and adjust the SA using the Taxpayer Amendment option in Function RAMA (Record/Amend Assessment). See the On-line Company Tax Manual (COM) in the ‘Assessing’ business area for detailed guidance.

See the Enquiry Manual (EM) for guidance on making enquiries into returns and amended returns.

A company can amend its return while it is under enquiry, but any change that affects the tax payable, or the liability of another company, is effective only once you complete the enquiry (FA98/SCH18/PARA31).