42 CFR §440.155

1. (a)“Nursing facility services, other than in an institution for mental diseases” means services provided in a facility that—
   1. (1)Fully meets the requirements for a State license to provide, on a regular basis, health-related services to individuals who do not require hospital care, but whose mental or physical condition requires services that—
      1. (i)Are above the level of room and board; and
      2. (ii)Can be made available only through institutional facilities;
   2. (2)Has been certified to meet the requirements of subpart C of part 442 of this chapter as evidenced by a valid agreement between the Medicaid agency and the facility for providing nursing facility services and making payments for services under the plan; and
2. (b)“Nursing facility services” include services—
   1. (1)Considered appropriate by the State and provided by a religious nonmedical institution as defined in § 440.170(b); or
   2. (2)Provided by a facility located on an Indian reservation that—
      1. (i)Furnishes, on a regular basis, health-related services; and
      2. (ii)Is certified by the Secretary to meet the standards in subpart E of part 442 of this chapter.
3. (c)“Nursing facility services” may include services provided in a distinct part (as defined in § 483.5(b) of this chapter) of a facility other than a nursing facility if the distinct part (as defined in § 483.5(b) of this chapter)—
   1. (1)Meets all requirements for a nursing facility;
   2. (2)Is an identifiable unit, such as an entire ward or contiguous ward, a wing, floor, or building;
   3. (3)Consists of all beds and related facilities in the unit;
   4. (4)Houses all beneficiaries for whom payment is being made for nursing facility services, except as provided in paragraph (d) of this section;
   5. (5)Is clearly identified; and
   6. (6)Is approved in writing by the survey agency.
4. (d)If a State includes as nursing facility services those services provided by a distinct part of a facility other than a nursing facility, it may not require transfer of a beneficiary within or between facilities if, in the opinion of the attending physician, it might be harmful to the physical or mental health of the beneficiary.
5. (e)Nursing facility services may include services provided in a swing-bed hospital that has an approval to furnish nursing facility services.