Section 272(11) in The Naval Ceremonial, Conditions Of Service And Miscellaneous Regulations, 1964
(11)On re-entry, the re-entrant shall be required to refund any gratuity other than War Gratuity, received in respect of his former service within a period of 3 years from the date of his re-entry in not more than 36 monthly instalments from his pay. The first instalment shall be payable within three months from the date of re-entry.