Some info on this...I have a friend, not a client, who got notices from the IRS that he didn't file not one, but two years of 5500s for a retirement plan. I told him that I wouldn't let my clients do anything but pay the DFVC penalty and move on, but he was adamant that he mailed them (regular mail with no receipt, of course) and that he wanted to fight it. So I gave him some tips on what to say (filed religiously for many years w/no problem, new procedures in place, blah blah) and...a month or two later, he got a letter back with these words: “based on the information you provided, we will not assess the late filing penalty on the account listed above for tax periods 2006 and 2007, form 5500, plan 001”. They even apologized for the hassle!
I'll get a lunch out of it.
I don't know that I'll change my approach with my own clients, but there it is.