Why was my hospital stay billed as observation instead of inpatient?

This is one of the most frustrating surprises in Medicare, and it catches a lot of people off guard.When you arrive at a hospital, the doctor has to decide whether your situation clearly requires inpatient admission or whether you need monitoring and testing before that determination can be made. If it is the latter, you may be placed on observation status. You might be in a hospital bed for two or three days and still never technically be admitted as an inpatient.Why does that matter? Because Medicare treats observation as outpatient care, not inpatient care. Under Part B (outpatient), your cost sharing works differently and can sometimes be higher for certain services and medications. More importantly, Medicare requires a three-day inpatient hospital stay before it will cover skilled nursing facility care afterward. Observation days do not count toward that three days.Hospitals are supposed to notify you in writing if you are on observation status for more than 24 hours. This is called a Medicare Outpatient Observation Notice, or MOON. If you receive one, ask questions right away. You have the right to ask your doctor why you are not being admitted as inpatient and to request a review if you disagree.If you are on a Medicare Advantage plan, the rules can differ slightly, so check with your plan directly. Coverage details vary and it is worth verifying your specific situation.