The Centers for Medicare & Medicaid Services (CMS) requires that all 
hospitals and critical access hospitals (CAH) provide the Medicare Outpatient 
Observation Notice (MOON) to beneficiaries in Original Medicare 
(fee-for-service) and Medicare Advantage enrollees who receive observation 
services as an outpatient for more than 24 hours.
The hospital or CAH must issue the MOON no later than 36 hours after 
observation services as an outpatient begin. This also applies to beneficiaries 
in the following circumstances:
- beneficiaries who do not have Part B coverage (as noted on the MOON, 
observation stays are covered under Medicare Part B);
- beneficiaries who are subsequently admitted as an inpatient prior to the 
required delivery of the MOON;
- beneficiaries for whom Medicare is either the primary or secondary 
payer.
To access the MOON and completion instructions, please visit the CMS website.