(1) The monthly rate of old-age pension or invalidity pension payable to an insured person shall be calculate in accordance with the following formula, namely:-

Average monthly wages x Number of years of insurable employment.

A period of six months or more of insurable employment shall be treated as one full year. No account shall be taken of any period of Insurable employment completed by the insured person after becoming entitled to old-age pension.

(2) The average monthly wages of an insured person, referred to in paragraph (1) shall be calculated on the basis of wages on which contributions were payable in respect of the twelve calendar months immediately preceding the date on which the insured person fulfills the condition specified in Section 22 or Section 23 as the case may be:

Provided that the old-age pension or invalidity pension payable to an insured person shall not be less than four hundred and twenty-five rupees per month for pension commencing on or after the first day of July, 1991.

(3) The minimum old-age pension under sub-section (2-A) of Section 22 shall be paid at the following rates, namely:-