U.S. Postal Service employee Louis Hatcher directs traffic at the Main Post Office on Brook Road as last-minute filers arrive Monday to drop off their federal income tax documents before the deadline. The goal: To have their letters and envelopes postmarked April 18 to avoid penalties for late filing. The deadline is usually April 15, but it was extended this year because of Washington’s annual D.C. Emancipation Day holiday commemorating President Abraham Lincoln’s signing of a law on April 16, 1862, abolishing slavery in the nation’s capital. Although the holiday is recognized only in the District of Columbia, the IRS recognizes the day as a legal holiday and extends tax filing until the next business day when it falls on a Friday or during a weekend.