42 CFR §447.280

1. (a)General rule. If the State plan provides for NF services furnished by a swing-bed hospital, as specified in §§ 440.40(a) and 440.150(f) of this chapter, the methods and standards used to determine payment rates for routine NF services must—
   1. (1)Provide for payment at the average rate per patient day paid to NFs, as applicable, for routine services furnished during the previous calendar year; or
   2. (2)Meet the State plan and payment requirements described in this subpart, as applicable.
2. (b)Application of the rule. The payment methodology used by a State to set payment rates for routine NF services must apply to all swing-bed hospitals in the State.