My understanding has long been that in counting out time for a statute of limitations, one begins with the day aftrer the triggering event. The Federal Rules of Civil Procedure tell us to do that (Fed. R. Civ. P. 6(a)(1)(A)), and my state jurisdiction, Illinois, has a statute that seems to say so as well (the Statute on Statutes, 5 ILCS 70). The Illinois provisions states:
"The time within which any act provided by law is to be done shall be computed by excluding the first day and including the last, unless the last day is Saturday or Sunday or is a holiday as defined or fixed in any statute now or hereafter in force in this State, and then it shall also be excluded. If the day succeeding such Saturday, Sunday or holiday is also a holiday or a Saturday or Sunday then such succeeding day shall also be excluded." (5 ILCS 70/1.11.)
Federal Rule 6(a)(1)(A) uses similar language, telling us to "exclude the day of the event that triggers the period".
This seems straightforward enough. However, as Joseph R. Marconi recently wrote in an article published by ISBA Mutual (a provider of lawyers' professional liability insurance), it may not be as clear as we thought. One intermediate appellate court and one Justice of the Illinois Supreme Court have treated the issue as subject to debate, raising the possibility that a limitations period actually expires on the day before the anniversary date of a triggering event. See his article, "What Can You Count On These Days?" for details.
One thing is clear -- don't wait until the last day to file. While the law seems to be settled for now, even the mere possibility that the ultimate day is really the penultimate day should be enough incentive to file earlier.