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HMRC internal manual

Shares and Assets Valuation Manual

HM Revenue & Customs
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Self Assessment: What is Self Assessment?

Self Assessment (SA) is the system for assessing and collecting income tax and capital gains tax. It was introduced by the Finance Act 1994 with effect from the tax year commencing 6 April 1996.

Initially, SA only applied to taxpayers who were individuals, trusts or partnerships. However, SA was extended to taxpayer companies for accounting periods ending on or after 1 July 1999.

Prior to the introduction of SA, taxpayers were required to supply information to HMRC in order that HMRC could issue an assessment - the legal charge to tax. Under SA it is the taxpayer who creates the legal charge to tax by making a self-assessment of their liability for any year.

Detailed instructions for the conduct of enquiries under the Self Assessment regime are given in HMRC Enquiry Manual (EM).

  Additional Guidance: SVM150000