Under section 36(1) (iv) the deduction allowable is in respect of "any sum paid by the assessee as an employer by way of contribution towards a Recognised Provident Fund or an approved superannuation fund, subject to such limits as may be prescribed for the purpose of recognising the Provident Fund or approving the superannuation fund, as the case may be." Rule 2(c) of Part A of the Fourth Schedule defines contribution" as meaning "any sum credited by or on behalf of any employee out of his salary, or by an employer out of his own monies, to the individual account of an employee, but does not include any sum credited as interest." Rule 4 of Part A of the Fourth Schedule lays down the conditions which are required to be satisfied by a Provident Fund in order that it may receive and retain recognition and the conditions in cls.(b) and (c) are material and these conditions are: "4(b) the contributions of an employee in any year shall be a definite proportion of his salary for that year, and shall be deducted by the employer from the employee 's salary in that proportion, at each periodical payment of such salary in that year, and credited to the employee 's individual account in the fund; (c) the contributions of an employer to the individual account of an employee in any year shall not exceed the amount of the contributions of the employee in that year, and shall be credited to the employee 's individual account at intervals not exceeding one year.