Sum range accross files with index match

Hello

I need to sum a range of data depending on current month accross two files. Hence I cannot use sumif/sumproduct.

In the attached picture I need a formula in cell B9 that sums row 4 from jan-17 to current month (cell B8) ((3+3+9) = 15)

Note that my data i row 3 and 4 in my real problem is in another file, so i need to use index to prevent that I have to open the data document when i update my month in B8.

Try

=SUMPRODUCT(([in1.xlsx]Sheet1!$B4:$M4)*([in1.xlsx]Sheet1!$B$3:$M$3<=B8))

In1.xlsx is the source data

But sumproduct formulas doesn't work accross files?

Originally Posted by BjarkeSK

But sumproduct formulas doesn't work accross files?

What makes you think that? SUMPRODUCT does indeed work on closed workbooks. INDEX does not.