@Glen Are you in northern Illinois also?  There were two disaster declarations there, I think the dates were July and September, sounds like your client might be in an area impacted by both.  

@Camp1040 If I know the penalty is going to be assessed, I will add it to the balance due (or subtract it from the refund, which happens more often than it should, and results in the credit-elect being changed without my knowledge).  This year I had two clients who had to have their arms twisted to file in March, rather than follow their usual custom of waiting until April 15, and did not really understand why it would save them $105.