Don't say the nation's capital never does anything for you. Thanks to a District of Columbia (DC) holiday, the IRS moved Tax Day back three days to April 18 this year.

Since 1955, April 15 has served as Tax Day in the United States, but the IRS can delay the filing deadline when it coincides with a holiday. While there is no national holiday on April 15, there is one in DC. Since 2005 the city has celebrated Emancipation Day on April 16, recognizing the date in 1862 when President Lincoln signed the DC Compensated Emancipation Act and abolished slavery in the District—eight months before the Emancipation Proclamation. When April 16 falls on a Saturday, as it does this year, DC observes the holiday on Friday, April 15.

While the federal government does not honor Emancipation Day, the IRS recognizes it as a "legal holiday" because it’s observed in DC. As such, they moved Tax Day to the next Monday and gave all Americans an extra three days to complete their 1040s. (Residents of Maine and Massachusetts get yet more time because they celebrate Patriots Day on April 18, but the rest of the nation does not benefit from that local holiday.)

Moving Tax Day back a few days is not only a victory for procrastinating Americans, it's also a role-reversal for DC, which has a complicated and often one-sided relationship with the federal government. Because the Constitution grants Congress authority over the District "in all cases whatsoever," federal lawmakers often meddle with DC's government. Congress has used its authority to block DC laws on marijuana, abortion, and clean-needles. Until a court ruling this March, DC could not even spend its own budget funds on anything without congressional approval, putting its tax dollars and government spending in limbo every time Congress got into one of its budget spat. And the federal government will probably never allow DC to tax the income of nonresident commuters who work in the city. Not to mention the 670,000 residents of DC that still don't get a vote in Congress.

But every few years DC gets to flip the script and push back the federal government's Tax Day, providing filers throughout the country a brief reprieve. So give DC a thank you.