The day taken can be accounted for any way you choose. Most businesses will dock some form of accrued time off. If you provide the standard Vacation, Personal, Sick, and Floating Holiday then usually the day taken falls into the category of Personal or Floating Holiday. Otherwise using vacation time is an option. Allowing for the use of Sick time is not advised as you are now creating an opportunity for sick time to be used as if it is additional vacation time, which is not its intent. Making the day unpaid may cause you some trouble with the Fair Labor Standards Act (FLSA), so be sure to review any such decision with an HR professional or attorney beforehand.