In the absence of any provision to the contrary, under self-assessment for the purposes of income tax, the normal rule is that claims are to be made within four years from the end of the tax year to which they relate. Before 1 April 2010, the time limit was generally five years from 31 January following the end of the tax year.
Some of the other specific income tax provisions are as below.
Trading income claims and elections
Two year averaging of profits of farmers or creative artists
first anniversary of the normal self-assessment filing date for the second tax year