Section 146(2) in The Navy (Pension) Regulations, 1964
(2)Notwithstanding anything contained in sub-regulation (1) where the total amount of pension or pensions of an officer (other than an officer of the Branch List) is less than Rupees Two Thousand and Four Hundred a year, a portion of the pension not exceeding Rupees Four Hundred may be commuted, provided that not less than Rupees One Thousand and Six Hundred a year remains uncommuted.