But psychologically, the added time makes a big difference to many filers.

2011 turns out to be a procrastinator's tax-filing dream year. The April filing deadline was three days later because Friday, April 15 was a federal holiday, pushing the due date to Monday. And the millions of taxpayers who got an extension don't have to get their tax returns to the Internal Revenue Service until Oct. 17 since the usual Oct. 15 deadline falls on Saturday.

Why we wait

Arthur J. Bangs, a licensed psychologist and professor of education at La Salle University in Philadelphia, teaches workshops to help people overcome procrastination. Over the years, he's noted some trends.

"Some feel it's safer to do nothing," says Bangs. They think they can avoid making mistakes by putting off the task.

Others procrastinate when facing a job they're unsure of how to perform, says Bangs. The end result is that complicated chores are pushed back in favor of easier ones.

Then there are perfectionists who put off doing things because they fear they won't do it well enough, as well as the rebels who don't want to follow someone else's rules.

And, of course, there's the excuse of, "I work better under pressure," so these people put off things until the very last minute.

Sound familiar, taxpayers?

Tough tax cycle to break

"For me, if I've got enough time to get something done, then I'm going to take all the time I have to get it done," says Jay Fleischman, a bankruptcy lawyer and managing attorney at Shaev and Fleischman in New York City.

Filing for a tax extension is not unusual for Fleischman, who then finds himself pushing the October deadline. "It becomes less and less important because it's farther away," he says, until the time his accountant "yells at me, 'Now I really need that.'"

In reality, most of Fleischman's tax information is already in his CPA's hands, so it can be used to calculate the estimated taxes Fleischman pays each year.

So why does he usually get a filing extension?

"Part of the reason I do it every year is that I did it one year," Fleischman says. "If I've got to file by Oct. 15, then April 15 seems like it's right after that. Didn't I just get my taxes done? Didn't I just finish this? It kind of becomes this self-fulfilling prophecy."

Fleischman is not alone.

According to a TurboTax survey, 30 percent of taxpayers who filed an extension for tax year 2009 waited until Oct. 1 to finish their returns. Most of those extreme tax procrastinators were men who filed a Schedule C to report income from their small businesses.