After filing late once, they can use their "Get Out Of Jail Free" one-time abatement card.  And since when is it our job to tell clients the penalty for not filing on time?  I think by now everyone knows April 15 (sometimes, 16, 17, or 18) is what the law requires.  Do we also have to tell them not to exceed the speed limit on the way to the office (sometimes, at least by not more than 10 mph). 

But we should probably know the rule well enough that if they are 55 days past the due date, they should use a faster delivery service than First Class Mail, since that often takes more than a week now.