MOON Notice
Medicare Outpatient Observation Notice — required to be issued to patients receiving observation services for more than 24 hours.
1 min read · Last reviewed May 23, 2026
At a glance
- Category
- Documentation
- Primary sources
- 1
- Workspace handoff
- templates →
Where this comes up
Providers meet this term in the chart and at the post-visit review — encounter notes, problem lists, medication reconciliation, signed orders, and the time/elements that defend the billed code. If documentation does not support the code, the code does not survive an audit.
Full definition
What it is in practice
CMS MOON explains the patient's outpatient status, the cost implications, and the impact on SNF qualification. Issued within 36 hours of observation start.
How it shows up in your practice
Track MOON issuance for compliance. Build into the observation order workflow.
Sources
- CMS — Observation Carehttps://www.cms.gov/medicare/regulations-guidance/two-midnight-rule
Use the MOON template
Open templates →Related terms
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Related across the archive
- GlossaryObservation CareHospital outpatient status used when the patient requires monitoring but does not meet inpatient admission criteria.
- GlossaryTwo-Midnight RuleMedicare policy that generally treats a stay spanning two midnights as appropriate for inpatient admission.
- GlossaryAddendum to Medical RecordA signed and dated note added to a medical record after the original encounter to clarify or supplement documentation.
- GlossaryDesignated Health Service (DHS)Categories of services subject to the physician self-referral prohibition under the Stark Law.
- GlossaryDocumentation CloningThe practice of copying prior or template-generated documentation into a new encounter note without updating it for the current visit.
- GlossaryDocumentation SpecificityThe level of detail in clinical documentation needed to support the diagnosis and service codes reported.
- GlossaryE-Prescribing of Controlled Substances (EPCS)DEA-regulated electronic prescribing of Schedule II-V controlled substances.
- GlossaryHCC (Hierarchical Condition Category)The CMS risk-adjustment model that groups ICD-10 codes into categories used to predict the cost of care for Medicare Advantage enrollees.
This glossary entry is a research aid for billing and compliance staff. It does not provide legal, medical, or financial advice and does not replace counsel. References cited link to primary sources at HHS, OCR, CMS, eCFR, NIST, and the relevant payer or industry body.