Nothing may be certain but death and taxes, but new research warns that a higher risk of fatal car crashes on the day of the IRS deadline might be one way the two get combined.

Matt Rourke / AP file

A taxpayer hands off his return at a drive-up postal drop in 2006. New research suggests that the risk of fatal car crashes jumps by 6 percent on the day of the IRS deadline.

More people die in auto accidents on income tax day in the U.S. than on other comparable days -- about 13 more per day, in fact, according to Canadian researchers who studied 30 years of data.

The pressure of the looming Internal Revenue Service tax deadline -- and the fact that about 20 percent of all taxpayers wait until the last minute to file -- may contribute to a 6 percent higher risk of dying as a driver, passenger or even a pedestrian on tax day, which this year is next Tuesday, April 17.

“All of a sudden there’s one source of stress that’s onerous, synchronized, repeated and applies to a huge community,” said Dr. Donald A. Redelmeier, an internist and researcher at the University of Toronto known for reporting the risk of auto crash deaths tied to cell phones, the Super Bowl and U.S. election days, among other topics.

In the new study, Redelmeier and his colleague, Christopher B. Yarnell, both of Sunnybrook Research Institute, reviewed U.S. tax and traffic fatality data from 1980 to 2009.

No question, tax time is stressful for many of those who file 141 million individual returns, according to IRS figures. Elaine Smith, a “master tax adviser” for H&R Block, a leading tax preparation firm, says there’s no shortage of tense taxpayers in early April.

“I just met this morning with two very frantic people,” she said Monday. “My schedule is packed the rest of the day with frantic people.”

The most pressure comes from simply putting off the chore until the last minute, Smith says. Other folks are frazzled because of changes in their tax situation -- a new house, retirement, a child leaves home.

“They’ve always been getting a refund and they’re afraid this year that they’re going to owe,” she said.

Apparently, that stress translates into more traffic accidents, according to Redelmeier’s research, published in a research letter in the latest issue of the Journal of the American Medical Association.

His team compared traffic deaths on 30 tax days with fatal accidents on control days in the same years, both one week before and one week after the IRS deadline. Of some 19,541 crashes, there were 404 deaths during the three decades.

“We indirectly minimize for differences in gas prices, vehicle technology, prevailing laws, health care access and other confounding contributors,” Redelmeier explained.

They found that there were 213 fatal crashes on the average control days -- but 226 crashes on tax days.

What’s more, Redelmeier says that although the data focused on deaths associated with the higher risk, the fallout likely extends to non-fatal accidents and property damage as well.

“The average crash causes about $8,000 worth of damage,” Redelmeier said. “The 6 percent increase in risk would amount to about $40 million in societal costs due solely to the surge of crashes on tax day.”

That’s equal to the average tax burden of about 5,000 Americans, he added.

The study found that the higher risk was most apparent during the past two decades and in people younger than 65. While one might have expected the advent of electronic filing to lower the risk in recent years because taxpayers didn’t have to drive to the post office to mail returns, that didn’t happen, Redelmeier said.

“Electronic filing is not making this go away,” he said. “And we don’t think it’s due to increased amounts of driving.”

Instead, the researchers speculate that it’s the overall stress of the day, perhaps combined with lack of sleep and what he called “less tolerance of hassles.”

“Stressful deadlines lead to driver distraction and human error,” he said.

A spokesman for the IRS says the agency is sympathetic to the plight of harried taxpayers and offers tools and advice on a federal website to help.

“We do everything we can to make it less stressful,” said Anthony Burke, an agency spokesman.

Still, that’s small comfort, even for people who’ve already filed their 1040s. Redelmeier notes that it’s hard to escape the extra risk of fatal crashes. Even if you’re not worked up over taxes, the guy in the next lane might be.

The solution, he offered, is for all harried taxpayers to take a deep breath before they hit the road on April 17.

Buckle seatbelts, slow down, pay attention to driving -- not to distracting thoughts about how much you might owe Uncle Sam.

“Almost all of these fatalities could have been prevented with a small change in driver behavior,” Redelmeier said. “There is no way to avoid stress, but there are countless ways to make a stressful situation worse.”

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