; and (2) the employee is filling a position that would otherwise be difficult to fill, as determined by the Secretary, in the absence of an incentive. (c) Housing vouchers (1) In general Subject to paragraph (2), not later than 1 year after the date of enactment of the Restoring Accountability in the Indian Health Service Act of 2017 , the Secretary may establish a program to provide tenant-based rental assistance to an employee of the Service who— (A) agrees to serve for not less than 1 year at a Service unit designated by the Administrator of the Health Resources and Services Administration as a health professional shortage area, as defined in section 332(a) of the Public Health Service Act ( 42 U.S.C. 254e(a) ); and (B) is a critical employee, as determined by the Secretary. (2) Sunset Any program established by the Secretary under paragraph (1) shall terminate on the date that is 3 years after the date on which any such program is established. (d) Administration (1) OPM guidelines The Secretary shall carry out this section in accordance with any guidelines of the Office of Personnel Management relating to the recruitment and retention of employees, including section 575.109 of title 5, Code of Federal Regulations (as in effect on the date of enactment of the Restoring Accountability in the Indian Health Service Act of 2017 ). (2) Service agreements The Secretary may only provide reimbursement for any relocation costs under subsection (b) or any other benefit under subsection (c) to— (A) a full-time employee who agrees to serve for not less than 1 year in the Service, beginning on the date of the agreement