“ In consultation with the Secretary of the Treasury, the authority of the President under 5 U.S.C. 5724b to prescribe the regulations provided for therein relating to reimbursement of Federal, State, and city income taxes for travel, transportation, and relocation expenses of employees, transferred at Government expense, furnished in kind or for which reimbursement or an allowance is provided.
" (c) The authority of the President to prescribe guidance pursuant to which each agency shall carry out its responsibilities under 5 U.S.C. 5724c.". ”