Date based accrual formula adding time

Hoping someone can figure out what it going on with this formula! I'm trying to create a formula that will automatically calculate an employees vacation balance based on three variable:

1. The employees start date relative to the date the entry is made
2. The accrual of .8333 days per month (10 days off per year divided by 12 months)
3. The subtraction of any PTO that is accounted for in column E of the spreadsheet

The formula in column G almost works but it is adding time at slightly increasing increments as the formula is applied to future entries. To be more specific: in cell G6 it adds 1, in cell G7 approximately 1.2 and up and up...

Formula currently looks like this:

=IF((YEAR(D6)-YEAR(D5))*12+MONTH(D6)-MONTH(D5)>0,(G5+((YEAR(D6)-YEAR(D5))*12+MONTH(D6)-MONTH(D5)*10/12))-E6,(G5-E6))

Spreadsheet is attached but to map the fields:

D6 = Date of entry
D5 = Date of previous entry
G5 = Previous balance (in days)
E6 = Number of days to be subtracted from employee vacation balance


Totally stumped and any help is appreciated!

You might be able to simplify the formula using DATEDIF to get the difference in months -try this formula in G6 copied down

=DATEDIF(D5-DAY(D5)+1,D6,"m")*10/12+G5-E6