Commencement of assessment period defined-intimation to authority starts and ends on receipt of withdrawal order. Amendment inserts clause (iia) into Explanation I of section 153 to define the period that commences when the Assessing Officer intimates the Central Government or the prescribed authority about contravention of specified exemption provisions of Section Ten under the proviso to the assessment procedure and ends when the Assessing Officer receives the copy of the order withdrawing approval or rescinding the notification under those provisions.