Section 7(1) in The Indian Supply Service (Group `A') Rules, 2017
(1)Notwithstanding anything contained in rule 8, where the Government is of the opinion that it is necessary or expedient to do so, it may for reasons to be recorded in writing and in consultation with the Commission, fill a duty post in any grade by deputation for a period not exceeding three years, which may be in special circumstances be extended upto five years as the Central Government may think fit.
