is " hospital care assurance"

I have some question and need your help. I had a baby this summer and my insurance covered most of my bill. but I still owed the hospital around $600. We got a letter from the hospital and ask us to apply for "hospital care assurance ". they said we can send the proof of our income last year. if our income is too low. they will write off our bablance. if i submit the application and get approved, is this going to affect my green card application? thank you a lot