Formula to calculate years from date (before/after June 30)

Hi all,

For the purpose of automating vacation time allotment - I am looking for a way to calculate the number of years between dates (ie. the start date of an employee to present) - catch is, the number of applicable 'years' change if the start date is before June 30 Additionally, a new year's worth of vacation time is accrued on January 1st of each year.

Example - an employee who started on June 30 2011 qualifies for 1 year's worth of vacation by the next day (July 1) and then another year come Jan 1 of the following year....an employee who starts on July 1 does not qualify for 1 year's worth of vacation until January 1 of the following year...hope this makes sense - sample attached
TIA
test vacation.xls