Section 19(1)(a) in Rajasthan Civil Services (Pension) Rules, 1996
(a)he shall be required to refund the bonus and/or gratuity received in respect of his earlier military service, in monthly instalments not exceeding thirty six in number, alongwith interest @ 6 % per annum from the date of his joining service under the State Government the first instalment beginning from the month in which he exercised the option.