Except for a proceeding under sub-section (2) of section 26, section 28, sub-section (1) of section 31 and section 33, no proceeding for assessment of tax payable by a dealer under this Act in respect of any period shall be initiated and completed except before the expiry of two years from the expiry of such period:
     Provided that a proceeding for re-assessment in pursuance of or as a result of an order on appeal, revision or review shall be initiated and completed before the expiry of one year from the expiry of the year during which such order was communicated to the assessing authority:
     Provided further that the Commissioner may, on being satisfied that it is necessary so to do and for reasons to be recorded in writing, extend in a case or class of cases, the said period of two years to such further period not exceeding two years.