The doc's script will allow the DME to give you a machine, mask, etc., but that separate med. necessity form is what is needed for the DME to file for the pt.'s insurance coverage. If the med. necessity form is not signed and returned to the DME, the DME must bill the pt. for the full cost of the machine, etc.
This came to my attention when I discovered that the sleep center failed to get a signed med. necessity form over to my DME. It should have happened nine months ago when I got my machine, but has yet to be accomplished. Meanwhile, my DME account shows that I'm paid up. Because of that, my DME has not been issuing me any monthly bills. Knowing there are no free lunches, I called the DME to ask about my acct. and how it's showing that I owe nothing.
My DME's billing dept. rep. told me that they're now going after that med. necessity form that they need to file with medicare. When they receive it now, what will I owe--20% of the full cost of my machine's total price? The DME doesn't know; it depends on how Medicare decides to bill--either the full 20% will be due, or they could start the 13 month rent-to-own pay procedure now even though it would be later than the usual time period.
The good news, according to my DME, is that it is quite unusual for the sleep center and doc to not submit the med. necessity form at the time the doc writes the script for a pt's new machine. So, hopefully, others will not face this situation.