I also got the message saying that my thing was filed but I still need to mail something in. The thing to mail in was a payment voucher.
This was for an AMENDMENT I made to my taxes
I spoke over the phone with someone and he said that I was getting the message come up because I had originally owed on the taxes.
However, even though I originally owed, I had already paid this digitally, and I did not owe anything extra when I amended it, so he said I DO NOT have to mail anything in, even though the screen pretty explicitly said I did.
Of course always check for yourself personally and your specific circumstances, but this was reassuring to hear because it seemed weird I would have to mail something in.
