SolvedCH51540 | Assessing Time Limits: The Time Limits: When the new time limits take effect: Income tax, capital gains tax and corporation tax - normal and extended time limits
From HM Revenue & Customs · Compliance Handbook
CH51550 sets out the transitional provisions applying to direct taxes. Where these transitional provisions do not apply the following time limits will apply with effect from 1 April 2010.
For income tax, capital gains tax and corporation tax, the new time limits, see CH51300, apply to any assessment made on or after 1 April 2010, regardless of the tax year or accounting period involved.
For example
If you are making discovery assessments under TMA70/S29 to make good a loss of income tax due to negligent or careless behaviour
on 31 March 2010 you would be able to assess all years back to and including 1989-90
on 1 April 2010 you would be able to assess all years back to and including 2003-04. The new time limit is 6 years from 6 April 2004, and
on 6 April 2010 you would be able to assess all years back to and including 2004-05. The time limit for 2003-04 has just passed.
If you are making CT discovery assessments under FA08/SCH18/PARA41 on a company that makes its accounts up to 31 March and there was no careless or deliberate behaviour
on 31 March 2010 you would be able to assess all APs back to and including that ended 31 March 2004, and
on 1 April 2010 you would be able to assess all APs back to and including 31 March 2007. The 4-year limit for assessing the AP ended 31 March 2006 has just passed.