Leap days may be good news for anyone who gets paid hourly. Not so much for some salaried workers.

Ryan Watkins, an employment lawyer with Whitten & Lublin Employment Lawyers,told CTV News thatemployees who are paid hourly are compensated for all actual hours worked. Salaried employees paid on a weekly or bi-weekly basis would also be paid for working on Feb. 29.

But it’s different for those paid monthly or semi-monthly -- once on the 15th and once on the last day of the month. If employees work a leap day they would likely not be eligible for additional pay.

“Unless there is a stipulation in the employee's employment contract that says that they get paid for this extra day, they're not going to get paid,” Watkins explained. “Employers are kind of getting away scot-free.”

He said Canadian employers are saving lots of money from their salaried workers each leap day.

“They're working an extra day for free, effectively,” Watkins added.

Why do we have a leap day?

Experts say without the leap day the timing of the seasons would all change.

“In just the span of 700 years, if we didn’t do this correction, the summer that we experience now in June, would actually have shifted all the way to December,” explained The Great Orbax, a science communicator with the Department of Physics at the University of Guelph, in a video posted online.

Orbax said it takes approximately 365 days and 6 hours for the Earth to complete one full orbit around the sun. But that would mean each year would have to start six hours late.

“Instead of changing our whole calendar, what we do is we save up those six hours, and every four years that makes 24 hours, and we tag on an extra day,” he explained in an interview with CTV News.

MORE: What could go wrong without leap years? More than you might think

But it’s even more complicated than that.

It actually takes the Earth 365 days, five hours, 48 minutes and 46 seconds to fully orbit the sun.

Over four years we actually end up 45 minutes short.

MORE: Leap day mathematical breakdown

“But it works out well, because every 100 years we end up with a whole day extra, and we take that one away from what would otherwise have been a leap year,” Orbax explained.

That extra day is added every 400 years.

“This extra day accumulates pretty quickly and the reason that we do it is to keep our current calendar that we have now in line with what we picture the seasons to be.”

Orbax said fewer corrections would be needed if society followed a calendar based on the moon instead of the sun, but humans would still probably struggle to make the math work.