Excel formula to calculate vaction time

Hello all,
i am trying to figure out an excel formula to calculate vacation time here is my company's policy:
Vacation time does not roll over.

years of service	monthly vacation accrual	total days/year
less than 6	0.83	10
6 through 10	1.25	15
11 or more	1.66	20

new hire must complete 6 months. Ee will earn 1 day per completed month until the end of the calendar year, at the beginning of the following year ee will use schedule above not to exceed 10 days. if employee was hired after july 1st he must wait until 3rd year to use the schedule above.