Yearly Vacation Formula

I work for a small company and we are attempting to change the way that employee's vacations are calculated. My Excel knowledge is just enough to get me by. I am building a simple spreadsheet for each employee. We want to make their vacation time roll over each year on their anniversary date. In prior years, we would just use January 1 after the employee had been there a year or two. My question is can Excel take the employees start date and add the additional hours that are earned on the anniversary date automatically.