Paid Time Off Increases after so many months, how do I calculate that?

I have been working on this for days and am having an extremely hard time! I need a spreadsheet that will calculate Paid Time Off from the date of hire to 85 + months. In between that time employees receive anywhere from 0 hours of paid time of to up to 10 hours depending on how long they have been with the company. I have figured out a formula to calculate day's. I have figured out also the Month() formula but it will not go past 12 months! It starts back over even though the time period is larger than 12 months! Please Help! I have attached the spreadsheet with example dates and what hours P.T.O. accrues at. Please someone help me get this right!


EX. P.T.O. Spreadsheet.xlsx

Yes if you work 1 to 3 months p.t.o. does not apply to but at month 4 it start to accrue at 6 hours per month and then increases after that. Is there some formula that will do what I am asking?

Month's 0 - 3 receive 0 Hours per Month
Month's 4 - 24 receive 6 Hours per Month
Month's 25 - 36 receive 7 Hours per Month
Month's 37 - 60 receive 8 Hours per Month
Month's 61 - 84 receive 9 Hours per Month
Month's 85 + receive 10 Hours per Month

It's alot of information and I can not figure it out and I'm sure that it is way less complicated than I am making it.
And thank you so much for the previous formula!

If it helps we get paid bi-weekly our current pay period is 9-17-2013 to 9-30-2013?

That lets me know what they should be earning per month but how can I have it calcualte what they have already earned or should have earned?

One formula I tried is this but it only works for the 4-24 months employees

=IF((F18>3),(F18-3)*6,0)

Am I on the right track?

If they are full time the employee gets so much of p.t.o. depending on the duration they have been here. The hard part is the formula that will show that. As soon as they hit 85 months they start to earn 10 hours per month. That also goes with the rest of the p.t.o. hours. So let's say that no one has used any of their p.t.o. they will have already accumulated 628 p.t.o. at start of their 86 month. The p.t.o. does always keep accumulating and does not end and start over because of a new year. This is the problem that I am having!

=IF(D10>84,(3*0)+(6*21)+(7*12)+(8*24)+(9*24)+((D10-84)*10),0)

I have that for all the people that have been here over 85 months but is there any way possible to make it universal so even those who have only been here 5 months can be included? Or am I going to need different formulas for each P.T.O. bracket?

Sorry D10 is their month to date on my spreadsheet and the numerical value is 92