Where any sum is found credited in the books of an assessee maintained for any previous year, and the assessee offers no explanation about the nature and source thereof or the explanation offered by him is not, in the opinion of the Assessing Officer, satisfactory, the sum so credited may be charged to income-tax as the income of the assessee of that previous year :

Provided that where the sum so credited consists of loan or borrowing or any such amount, by whatever name called, any explanation offered by such assessee shall be deemed to be not satisfactory, unless,—

(a) the person in whose name such credit is recorded in the books of such assessee also offers an explanation about the nature and source of such sum so credited; and

(b) such explanation in the opinion of the Assessing Officer aforesaid has been found to be satisfactory:

Provided further that where the assessee is a company (not being a company in which the public are substantially interested), and the sum so credited consists of share application money, share capital, share premium or any such amount by whatever name called, any explanation offered by such assessee-company shall be deemed to be not satisfactory, unless—

(a) the person, being a resident in whose name such credit is recorded in the books of such company also offers an explanation about the nature and source of such sum so credited; and

(b) such explanation in the opinion of the Assessing Officer aforesaid has been found to be satisfactory:

Provided also that nothing contained in the first proviso or second proviso shall apply if the person, in whose name the sum referred to therein is recorded, is a venture capital fund or a venture capital company as referred to in clause (23FB) of section 10.