Formula to calculate vacation hours

[thays]

I need a formula that will calculate vacation hours based on the anniversary date and depending on the length of service. For instance an employee with an anniversary date of 8/29/2012 would get 4 vacation hours for every 5 weeks employed in months 1 through 12, then 8 vacation hours for every 5 weeks in the months 13 through 24, and so on. So beginning January 2013 through August 2013 the employee would earn 4 hours for every 5 weeks, then September through December 2013 the employee would earn 8 hours for every 5 five weeks.

Thanks

[olasa]

Half year end/beginning weeks are tricky.
Max 40hrs/yr? --> Yr 1: =40hrs (4hrs*52/5,2)
//Ola

[thays]

Is that the formula? if so, does the formula start at the word Max and end at Ola?