The formula I'm using to do the first set of calculations is:

=SUMPRODUCT(--(B2:B5=DATEVALUE("1/1/2001")),C2:C5)/0.029+SUMPRODUCT(--(B2:B5<DATEVALUE("1/1/2001")),C2:C5)/0.03

"Jason" wrote:

Awesome, both of those formulas worked great. Thanks! I have one followup
question. I have the following data:

Category Date Amount
A 11/1/01 100.00
A 1/1/00 100.00
B 12/31/04 200.00
C 1/1/00 300.00

As stated before, I have the formula to sum the values in the fields and
divide the ones with invoice date before 1/1/01 by .03 and the ones after
1/1/01 by .029. However, is there a way to incorproate another formula that
will only calculate the ones in category A, then in a sepearte cell calculate
the ones in category B and so on and so fort.

Thanks,

Jason