Tax Day falls on April 15 most years -- but not 2018.
This year, Tax Day falls on Tuesday, April 17, a full two days later than normal. April 15 falls on a Sunday in 2018, which would normally push Tax Day to Monday, April 16.
That date, though, happens to be when Washington, D.C., is observing Emancipation Day. That holiday honors the 1862 passage of the District of Columbia Compensated Emancipation Act, which ended slavery in the nation's capital by paying slaveowners to pledge their loyalty to the Union and free their slaves.
Thus, Tax Day is pushed back yet another day to Tuesday, April 17. The holiday returns to its regular April 15 date for 2019.