Previous year determination: newly commenced businesses and income sources use period from commencement to next 31 March for assessment purposes. The amendment fixes the previous year for AY beginning 1 April 1989 for businesses, professions or income sources started between 1 April 1987 and 1 April 1988 with accounts not made up to 31 March 1988 as the period from commencement to 31 March 1989. If the assessee had adopted one or more periods as the previous year for AY beginning 1 April 1988 for any sources, the previous year for AY beginning 1 April 1989 must be reckoned separately for each such source, and the longer or longest of those separate periods shall be the previous year.