Check and double check your medical billing claims for the notorious wrong place-of-service (POS) code that can spell denials and delays in getting paid for your observation services. A good general guideline to follow is to use POS 22 (Outpatient hospital) only for observation codes 99217 (Observation care discharge day management …) and 99218-99220 (Initial observation care, per day …). Be sure not to use POS 21 unless the patient has been formally admitted. You will need to split out the time the patient was in observation before they were admitted and use codes 99211-99215 for any E/M services rendered on the second day and before the patient is discharged. …