Although the holidays can be a joyful time, they can also be a hard, stressful season with end-of-year deadlines and family obligations.

Your colleagues can make this special time of year easier or harder, depending on their holiday attitudes.

“It’s that magical time of year where many of us start to forget what day it is and what time it is,” said Jacqueline M. Baker, founder of Scarlet Communications, a leadership training consultancy. “Unfortunately, it’s also that time of year that many of the things that we are careful and more diligent about, like workplace behavior and habits, also take a bit of a slip.”

Here are the kinds of co-workers that will get lumps of coal in their stockings and create unnecessary office nemeses over the holidays.

Don’t be one of them.

4. The ones who pressure their colleagues to meet a bunch of deadlines in December.

5. The ones who check out and expect colleagues to work hard in their absence.

The holiday season can be a time to take it easy, but the worst colleagues are those who leave all their to-dos on your plate while they head off to be merry. More mindful colleagues would not put any expectations on their team members to finish projects they started.

“The best way to show that you care about your colleague is to leave only a few tasks for them to do in your absence. You worked hard and deserve to take time off, but don’t put your end-of-year tasks on your colleagues,” Goehner said.