Can the secondary insurance provider deny a claim that was not filed with the primary insurance provider first?

Let me tell you what happend to me. I hope that this helps. I used to be covered by two insurance companies. My primary insurance company was through the company that I worked with. My secondary was with the company that my husband works with. When a claim was filed with my secondary insurance company they wanted to know how much my primary insurance company paid for and until then they would not pay anything. So I had to submit to my primary insurance company and once they paid some then the secondary would. I hope that this helped:) * Yes. A claim must always be made with the primary insurer first.