You will want to make the range absolute before copying down
=SUMPRODUCT((MONTH($A$7:$A$500)=ROW(A1))*($C$7:$C$ 500="gas")*$D$7:$D$500)

--
Don Guillett
Microsoft MVP Excel
SalesAid Software

"Don Guillett" wrote in message
...
Modify to suit. Assumes valid dates in col A, categories like gas in col c
and the amounts in d
=SUMPRODUCT((MONTH(A7:A500)=ROW(A1))*(C7:C500="gas ")*D7:D500)
I suggest using a credit card with a 1% or better rebate.
--
Don Guillett
Microsoft MVP Excel
SalesAid Software

"infamouswb" wrote in message
...
I use excel for my checkbook register and I have a budget that "runs"
beside
it to keep a monthly track of everything in the same worksheet. I want
to
write a formula that would take, for instance, my gasoline purchases from
the
checkbook, then place and continue to add up the monthly gasoline
purchases
in the budget column. I know very little about formulas. Right now, I
manually add up all the rows that say Gas for the month and place them
into
the budget line. I appreciate your assistance.