Tax due date: April 15... er no, this year, it's April 18!

Personal tax returns this year will be due on April 18th, for which you can thank Abraham Lincoln. He signed a proclamation ending slavery in Washington DC on April 16, 1862, and so DC celebrates this as a holiday, Emancipation Day, every April 16, or on the Friday before or Monday afterward if the 16th falls on a weekend.

This year, April 16 falls on a Saturday, so the holiday will be celebrated on Friday the 15th, and that means the IRS moves the due date for Form 1040 to the following Monday, April 18.

Another holiday, Patriot's Day, which falls on the third Monday of April and is celebrated in Massachusetts and Maine, used to affect the due date of tax returns, until the IRS moved its processing center from Andover, Massachusetts, out of the state. So Patriot's Day doesn't affect the due date of tax returns any more. Moving out of state (or, rather, district) is not an option for the IRS as regards Emancipation Day, though, because it is headquartered in Washington.

However, Emancipation Day will continue to affect tax due dates for the next couple of years. In 2017, tax day will fall on Tuesday April 18, and in 2018, your return will be due Tuesday April 17.