On Aug 18, 3:35 pm, Mana wrote:
On one tab, I have in column C the account number, in column I, I have the
amount. There are are series of account numbers. On a separate tab (summary
sheet), I have the account number in column A and in column B I want every
amount from the first tab to sum in column B, next to the associated account
number. How do I do that so it is a constant formula that does not have to
be manipulated every month?

=SUMIF(Sheet1!C:C,A1,Sheet1!I:I)

You'll have to adjust the ranges. And make sure your account numbers
have no typos.