Dave, try writing a letter explaining how the error occured and explain the steps you've take to correct the error so it never happens again, say how sorry you are and ask to have the penalty waived. You owe what you owe but the penalty and interest on it can be waived. I've done it twice, 2 different clients, and both times the penalty was waived. Saved about $1000 each time. Write a letter, beg for mercy, it's worth a try.