(a)in a ease where a dealer required to get himself registered under clause (a) or clause (b) of sub-section (2) has applied for registration within the period prescribed under clause (a) or specified in clause (b) of the said sub-section, the date on which his turnover in a year first exceeds the limit prescribed under sub-section (1) of Section 5 or the date of transfer of business, as the case may be;