It has to do with the arrangement you have set up with the hospital. It's also way more complicated than just the space issue.
In order to bill POS 22, as a outpatient department of the hospital, you have to actually BE a department of the hospital, with the organization covering all of the overhead of your practice. I'm assuming that you are leasing, or have some other sort of financial arrangement that places the practice and malpractice expense as your practice's responsibility. In that case, you bill POS 11 always. If the organization is covering your overhead, you may not be able to bill under your own TIN, either...this gets sticky, because you could be inadvertently entering into a Stark violation....where the hospital gets a financial benefit because you are providing services in their facility, and they encourage that by providing you 'free' rent as you bill under your own TIN.
In short...I always suggest seeking legal counsel when entering into arrangements with facilities where you could be at risk for billing compliance issues. I wouldn't attempt to get an answer to such a potentially complicated issue on this discussion board.
