42 CFR § 456.360 - Certification and recertification of need for inpatient care.
(a) Certification.
(1) A physician must certify for each applicant or beneficiary that ICF services are or were needed.
(2) The certification must be made at the time of admission or, if an individual applies for assistance while in an ICF, before the Medicaid agency authorizes payment.
(b) Recertification.
(1) A physician, or physician assistant or nurse practitioner (as defined in § 491.2 of this chapter) acting within the scope of practice as defined by State law and under the supervision of a physician, must recertify for each applicant or beneficiary that ICF services are needed.
(2) Recertification must be made at least—
(i) Every 12 months after certification in an institution for Individuals with Intellectual Disabilities or persons with related conditions; and
(ii) Every 60 days after certification in an ICF other than an institution for Individuals with Intellectual Disabilities or persons with related conditions.