Trying to calculate the Deferred Revenue release formula

Hi,

Currently I am having trouble figuring how I can calculate the revenue recognition for the correct period.

I have spreadsheet which runs from Jan 2011
example.

cell A2 = Invoice billing period
cell B2 = Date when the revenue recognition begins
cell D2 = Billing amount
cell E2 = Billing period covered

My problem is that I have 2 different conditions for same type of billing e.g. Monthly new business should recognised in the same billing period however, Monthly renewals should recognised in the following period.

The formula I m currently using is only reads the month and not the year so excel returns the value in the same billing month for all years 2011, 2012 and 2013.

=IF(AND(OR($B2<=F$1,MONTH($B2)=MONTH(F$1),YEAR($B2)=YEAR(F$1)),COUNTIF($E2:E2,">0")<=$E2),$D2/$E2,0)

Can someone guide me to the right direction

Thanks.