Subject to the condition that no deduction may be made which reduces the credit by more than the amount of any contribution by the Board with interest thereon credited under rule 10, 11 and 12 before the amount standing to the credit of a subscriber in the Fund is paid out of the Fund, the Board may direct the deduction therefrom and payment to the Board of-
(a) any amount, if a subscriber has been dismissed from the service for grave misconduct:
Provided that if the order of dismissal is subsequently cancelled, the amount so deducted shall, on his reinstatement in the service, be replaced at his credit in the Fund.
(b) if a subscriber resigns his employment under the Board within five years of the commencement thereof, otherwise than by reason of superannuation or a declaration by competent medical authority that he is unfit for further service;
(c) any amount due under a liability incurred by the subscriber to the Board.