Normally, federal income taxes are due on April 15th.  This year, it's April 18th.  But why?There is a little-known holiday outside of Washington DC call "Emancipation Day".  Officially, slavery wasn't abolished until December 6, 1865 when the 13th amendment was ratified. It happened much earlier in Washington DC.

Abraham Lincoln freed all the slaves in the District of Columbia on April 16, 1865.

This is now a legal holiday in Washington DC allowing all federal workers the day off. If April 16th falls on a weekend, it is celebrated on the closest weekday. Since it's a federal holiday, it takes precedence over tax day.  Therefore, tax day moves to April 18th this year.

If you are lucky enough to be in Maine or Massachusetts, you get an extra day. Your taxes aren't due until April 19th.

Patriots Day is celebrated there on the 3rd Monday of April.  Since that falls on the federal tax day this year, you get an extra day to file your taxes.