Sometimes, getting employees and contractors to stick to deadlines can seem futile--but it doesn't have to be that way.

According to Dr. Heidi Grant Halvorson, associate director for the Motivation Science Center at the Columbia University Business School and author of Nine Things Successful People Do Differently, there are three reasons that people miss deadlines--and a single simple solution for all three.

Here's how to keep your team on time and on target.

The Trouble with Distant Deadlines

Halvorson points out that the "Goal Looms Larger Effect"--the mechanism that makes imminent goals feel all-consuming, like when you're finishing a race or closing a sale, is the same effect that helps people hit deadlines. "The closer you get to success, the more intensely you pursue it," she writes.

As a deadline approaches, your employees will race toward that finish line. However, if the deadline is pushed back, they'll want to ease off and direct attention to other, closer goals. Meanwhile, the tendency to procrastinate adds a second challenge, says Halvorson. When people say, "I work better under pressure," what they mean is that they work because of pressure--and that without pressure, they don't work. Get rid of the deadline, and you eliminate the pressure needed to get tasks finished.

The third issue with allotting more time is that people are terrible at scheduling to begin with. There's "a pervasive tendency to underestimate how long it will take to do just about anything," writes Halvorson. This is only made worse by the fact that people generally plan for best-case scenarios, ignoring the fact that things rarely go smoothly. Pushing back a deadline without realistically looking at the schedule won't make a goal any easier to hit.

Staying on Target

The solution, says Halvorson, is not imposing a giant deadline. If there's a distant end date and no immediate pressure, it will be harder for employees to work, especially because of the challenges of planning out time.

Instead, managers should work with employees to break down large projects into a series of smaller deadlines to keep the pressure on and the workload manageable. A study by Dan Ariely and Klaus Wertenbroch bears this out: They found that students who turned in work at regular intervals during the semester got higher grades than those who chose to turn in all their work on the last possible day. 

But if you can't assign smaller deadlines and employees want more time, the best plan may be holding firm. Halvorson concludes: "If it's not possible to set interim deadlines or make sure actions are taken to avoid the planning fallacy, then you really should try to avoid pushing back your deadline altogether. The odds are good that you'll have little to show for it but wasted time."