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HMRC internal manual

Company Taxation Manual

Corporation Tax self-assessment (CTSA): capital allowances: consequential assessments or amendments


A company can make a capital allowance claim for an accounting period when a return for a later accounting period has already been made. This capital allowance claim may reduce the amount of capital allowances due for that later accounting period.

For example, a claim for machinery and plant allowances will reduce the machinery and plant pool and the capital allowances due for later periods. When this happens the company must make the necessary amendments to its return for that later period within 30 days, (Paragraph 83 (2)).

If the company does not amend that return within 30 days you can amend it to make it consistent with the capital allowances available (Paragraph 83 (3)). You must give the company written notice of any amendment that you make under this paragraph.

Paragraph 83 (4) extends the time limits that otherwise apply to the amendment of a company tax return so that an amendment made under Paragraph 83 (2) or (3) will not be out of time.

The company can appeal in writing against the amendment of the return. It must make the appeal:

  • in writing,
  • within 30 days of the issue of the notice of amendment,
  • to the HMRC office that issued the notice.