As a courtesy to your employer you should let them know about the required days of for yom tov.
In 2015 these are the dates- there are 8:
Passover April 10th
Rosh Hashana Sep 14-15
Yom Kippur Sep 23
Sukkot Sep 28-29
Sukkot last days Oct 5-6
(be sure to warn them about the need to leave early the night before).
Note that there is a shavuot this year but it coinsides with memorial day weekend- so that saves the need for another vacation day.