The MOON notice, in plain language
If you or a parent got a form called the Medicare Outpatient Observation Notice, or MOON, during a hospital stay, here is what it means, line by line, from an emergency physician.
What it is
The MOON is a standard Medicare form. It tells you that you are an outpatient under observation, not an admitted inpatient, even if you are in a hospital bed overnight.
When you get it
Hospitals must give it to people with Medicare who receive observation services for more than 24 hours. It must be given no later than 36 hours after observation starts, or sooner if you are going home. Someone should also explain it to you out loud.
What it means for your bill
- Part B, not Part A. Observation is outpatient care, so Part B copays can apply to each service instead of one inpatient deductible.
- Your daily pills. Medicines you normally take yourself may not be covered while you are under observation, and the hospital may bill you for them. Ask whether you can use your own.
- Rehab or a nursing facility. Medicare usually covers skilled nursing care only after 3 days in a row as an inpatient. Observation days do not count toward those 3 days.
Signing it
You will usually be asked to sign. Signing shows you received the notice. It does not mean you agree with your status. If you refuse to sign, staff note that and you still get a copy.
What to do next
- Ask: "Why am I under observation and not admitted? What would change that?"
- Ask for the case manager or social worker if rehab may follow your stay.
- Keep your copy with your discharge papers.
- For Medicare questions, call 1-800-MEDICARE. Medicare Advantage plans have their own rules, so call the number on your card.
Education only, not legal, insurance or medical advice. Rules can change; the notice you receive is the official version. In an emergency, call 911.
Common questions
Does signing the MOON mean I agree to observation status?
No. Your signature shows that you received the notice. It does not mean you agree with being classified as an outpatient.
Do I get a MOON if I have Medicare Advantage?
Hospitals give the MOON to people with Medicare, and that generally includes Medicare Advantage members. Your plan sets what you pay, so call the number on your card.
What if I never got a MOON?
If you have been under observation for more than 24 hours, ask the nurse or case manager for it. You can also call 1-800-MEDICARE.
Written and medically reviewed by Harvey Castro, MD, MBA, board-certified emergency physician. Last reviewed October 25, 2026.