Or the debt collectors haven't caught up yet. That happened to me around 2012 in the US. Went to the emergency room, had some tests done, got the hospital bill and paid a few hundred bucks. Then like 9 months later I get calls from a debt collector saying I owed $1,500 to a separate medical testing company that apparently provided the test I was given at the ER. I had never received that bill and it just took a while for them to send it to collection apparently.