<prompt> Human: Had claims originating from an ambulance visit and emergency room trip in September of 2016 for my wife. After a few months, I began receiving what seemed to be reasonable bills with reasonable explanations from my primary insurance company. A few months ago, however, I began to receive notices of denial for claims online and full bills for services rendered. The bill notes highlight that the claims have now been denied due to my wife having primary insurance other than mine at the time of service. At that time, we had been advised to update my wifes parents insurance with my insurance as my wife was on my wifes parents insurance still at the time. The real concern is that the insurance company my wifes parents used to have, they no longer currently have. I have been advised by both my primary insurance provider and the hospital to send bills to that other insurance provider regardless as they were active during the claims originations. Am I okay continuing to send the bills to the now no longer used insurance provider or should I be taking a different route? Any help is greatly appreciated! Edit: I want to say thank you to everyone for your responses. This is a new account following some random and threatening PMs to an account from last year... I say that because this sub has been so welcoming already. Thank you for the community and advice.  <response>: Yes, it is perfectly OK to send these bills to the old insurance company, even though she has different insurance now. She was under their coverage then, so they will process it. 