Accrual of hours
 

How do I create a formula that will accrue vacation hours on a monthly basis?
I've created a timesheet in excel version 2003. Each workbook contains a
bi-weekly timesheet. The last workbook is a YTD (year to date). I want to
add a formula that will show each month an employee accrued 1.66 days so I
can cross check what a person has used with what a person has accrued. Can
this be done?