It was something accountant Carol Soens could count on with the certainty of death and taxes: one of her clients strolling into her office on April 14 each year.

"I finally had to start charging him more," says Soens, who works in Michigan and is dubbed the "tax goddess" by her clients. "Then his wife got so fed up with it, she started calling me earlier in the year. She doesn't let him handle the taxes anymore."

Such is life for procrastinators — those who wait until the last minute to begin something they've been meaning to do and had ample time to complete (taxes, anyone?), nearly blowing deadlines and often causing tension with co-workers or friction in relationships.

But putting off projects and tasks to the last minute or later could do more than jeopardize your job, relationships or standing with the Internal Revenue Service — it could put your health at risk.

Chronic procrastinators suffer more headaches, gastric problems, cold and flu viruses, insomnia, muscle strains, infections and reproductive and menstrual problems than those who handle tasks promptly, says Fuschia Sirois, a researcher at the University of Windsor, Ontario.

We all procrastinate, but more of us are doing it more often, say researchers, who estimate that up to 26 percent of people are chronic procrastinators. Those who help procrastinators learn to complete tasks promptly say the numbers are probably higher.

"In my experience, it's a minority of people who do not procrastinate," says Marianna Swallow, a Chicago-based business trainer and consultant.

Dr. Matthew Ewald, a Detroit Medical Center family practice physician, says he is able to pick up on which of his patients are chronic procrastinators when they come to him for help dealing with stress, anxiety and depression and he asks them about their habits.

"Procrastination is all about stress," Ewald says. "It's not that procrastination causes the health problems; it's that it causes stress, which causes the problems."

Researchers are now recognizing that bad health can plague procrastinators throughout their lives.

Sirois says she found that people who procrastinate regularly are less likely than nonprocrastinators to take part in healthy behaviors like getting enough sleep, exercising moderately and eating well. They're also less likely to take preventive measures to safeguard their health.

"They don't take care of things such as making sure there are fresh batteries in the smoke detector, throwing out expired medications, putting away dangerous tools," Sirois says.

Procrastination was potentially more serious for breast cancer survivor Mary Hurd.

Not normally someone who puts things off, the 50-year-old Detroit mother and grandmother discovered a lump in her right breast in June 2005, the summer her son was preparing to leave for college. It was a busy time and she didn't want to worry him before he left. But it took her until November to see a doctor.

"The fear was so real," says Hurd, who has since undergone surgery, chemotherapy and radiation. Part of the reason Hurd put off going to the doctor, or even telling anyone, was because she wanted to believe that it would go away.

While her cancer is considered in remission, Hurd says she sometimes wonders if it would have progressed as far if she hadn't waited so long to get the lump checked.

So if chronic procrastination can lead to big problems, why do so many people do it?

It's not a matter of awareness, says Swallow.

"It is human nature to look at something that you don't like and say 'I don't want to do it,' " she says. Experts caution there is a difference between people who don't get things done because they procrastinate and those who don't get things done because they have too much to do.

A true procrastinator relies more on moods and feelings.