Section 6(1)(a) in The Orissa Civil Services (Commutation of Pension) Rules, 1992
(a)in the case of an applicant who is drawing his pension from a treasury, the reduction in the amount of pension on account of commutation shall be operative from the date of receipt of the commuted value of Pension or at the end of three months after issue of authority by the Accountant-General, Orissa for the payment of commuted value of pension, whichever is earlier; and