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HMRC internal manual

Company Taxation Manual

Corporation Tax self-assessment (CTSA): Assessments : Time limit


Unless the provisions of the Taxes Acts allow a longer period, the time limit for assessment is four years after the end of the accounting period. The time limit is, however, six years where the assessment is made to recover tax lost through carelessness, and 20 years through deliberate behaviour by the company or a related person, that is

  • a person acting on behalf of the company, or
  • a person who was a partner of the company at the relevant time.

For claims made before 1 April 2010, subject to transitional provisions at SI2009/403 art 10, the time limit was six years in all cases unless the loss of tax was attributable to fraudulent or negligent conduct, when the 20 year time limit applied.

A company can object to an assessment on the grounds that the time limit for making it has expired only by making an appeal against the assessment.