April 17 is new filing deadline. No joke!

No kidding. We all get one more day to work on our 1040s.

And the IRS is just as surprised as the rest of us, although probably not as happy about the change as we taxpayers are.

This filing season, a perfect calendar storm has produced the convergence of the already-delayed filing deadline, an official District of Columbia holiday and an obscure federal law. The result: More tax time.

Most of us were looking at Monday, April 16, as the due date for our 1040s, since the 15th this year fell on a Sunday. But 4/16 is the Emancipation Day holiday in Washington, D.C. And under a federal statute enacted decades ago, holidays observed in the District of Columbia have an impact nationwide.

That fact, however, slipped past everybody, including the IRS, until now. IRS publications, every package of tax-filing software and all those how-to-file guides in bookstores nationwide proclaim that Monday, April 16, as the deadline. Even Don’t Mess With Taxes‘ calendar (there in the right column and now corrected) had the erroneous date.

But in a statement issued yesterday, the agency acknowledged that "the IRS recently became aware of the intersection of the national filing day and the local observance of the new Emancipation Day holiday after most forms and publications for the current tax filing season went to print."

Yep, it’s been a tough year for printed tax publications. First the extender tax breaks that messed up the deduction claims on paper returns of the popular tax breaks and now this.

But at least in this case, the remedy is a bit easier. The discovery of the new due date means we all can simply ignore references to April 16. The following don’t have to be filed until the next day:

• Calendar-year 2006 federal individual income tax returns, whether filed electronically or on paper (Forms 1040, 1040A or 1040EZ).
  
• Requests for an automatic six-month tax-filing extension on an individual return for calendar-year 2006, whether submitted electronically or on Form 4868.
  
• Tax-year 2006 balance-due payments, whether made electronically (direct debit or credit card) or by check.
  
• Individual estimated tax payments for the first quarter of 2007, whether made electronically or by check.

The extra day also gives you 24 more hours to put money in an IRA and have it count as a 2006 contribution.

The IRS details additional situations where the April 17 date applies in a FAQ Web page about the deadline change.

The IRS is encouraging folks, however, not to wait until the very last minute. Yeah, like that’s going to happen. The agency’s other suggestion, to e-file instead of sending in paper returns, has a better chance of being followed.

But you can be sure that a good number of procrastinating taxpayers nationwide will once again be lined up at 11:55 p.m. on April 17 outside the local post office that stays open late on tax-deadline day.

Some filers already had extra time: While this new deadline is welcome news for most of us, a group of taxpayers already were looking at April 17 as the deadline.

Back in November, in fact, the IRS announced that residents of Massachusetts, Maine, Maryland, New Hampshire, New York, Vermont and the District of Columbia didn’t have to get their 1040s in until Tuesday, April 17, because of Patriots Day.

Why? Those filers’ returns are processed at the IRS facility in Andover, Mass., where Patriots Day is an official state holiday. Maine, which was once part of the Bay State, joins Massachusetts in celebrating this day dedicated to observing the 1775 battles of Lexington and Concord, the first conflicts of the American Revolutionary War.

As for Emancipation Day and possible future federal tax-filing deadlines? We won’t see the two coincide again until tax season 2011.

Don’t forget your state returns: Many states that require annual filings also follow IRS deadlines. In this case, though, state officials might be sticking to the original due date, i.e., Monday, April 16. So if you must complete state returns, check with your state’s tax office to see what this IRS change means.