42 CFR § 409.21
Nursing care
June 11, 2020
(a) Basic rule. Medicare pays for nursing care as posthospital SNF care when provided by or under the supervision of a registered professional nurse.
(b) Exception. Medicare does not pay for the services of a private duty nurse or attendant. An individual is not considered to be a private duty nurse or attendant if he or she is an SNF employee at the time the services are furnished.
[63 FR 26306, May 12, 1998]