42 CFR § 489.52
Notice to CMS.
(1) A provider that wishes to terminate its agreement, except for a SNF as specified in paragraph (a)(2) of this section, must send CMS written notice of its intention in accordance with paragraph (a)(3) of this section.
(2) A SNF that wishes to terminate its agreement due to closure of the facility must send CMS written notice of its intention at least 60 days prior to the date of closure, as required at § 483.70(l) of this chapter.
(3) The notice may state the intended date of termination which must be the first day of the month.