[RemydeHaviland]

I am not entirely clear on the circumstances

If you have two plans - Medicare and a Supplement of some sort, then it sounds like confusion based on their interaction / overlap

It sounds like Medicare is denying based on the fact that another insurance plan would have been "primary", ie - Medicare was not the primary "provider of coverage"

This could be the result of a coding issue by the service provider (hospital / physician, etc), as another poster mentioned

I would investigate further and see which plan would be "primary" for emergent care

Best of luck getting things resolved!