Robert, you hit the nail on the head... Years ago corporate client paid a penalty for "late filing" to Pennsylvania after receiving a notice... Client paid this before letting me know.... I called Pennsylvania and asked them if there would have been a late filing penalty if the client had an extension .. The gentleman said of course not .... So I said that's funny because we have a copy of the extension that was filed and the certified mail receipt... He said hold on a minute, and then came back and said it was a  mistake or error.... Client received credit for the amount that he should not have paid...