[Commutation of annuity.
90. Any payment in commutation of annuity shall not exceed-
(a) in a case where the employee receives any gratuity, the commuted value of [one-third] of the annuity which he is normally entitled to receive, and
(b) in any other case, the commuted value of [one-half] of such annuity,
such commuted value being determined having regard to the age of the recipient, the state of his health, the rate of interest and officially recognised tables of mortality.]