Sum values that match in different rows

[rlobera]

Hi guys!

I need some help regarding an issue that I was not able to solve. I tried to figure it out but without reaching my goal. This is what I have:

In sheet 1 I have estimated active customers for a period of time, where columns are months and rows are departments/states:

	Month 1	Month 2	Month 3	Month 4	Month 5
Department A	3	6	10	14	15
Department B	2	5	8	13	20
Department C	4	6	7	9	12

<tbody>
</tbody>

Then, in sheet 2, I'm forecasting sales and need excel to return values from sheet 1 depending on which month we are kicking-off for each department:

	Kick-off	Jan	Feb	Mar	Apr	May	Jun	Jul
Department A	Jan	3	6	10	14	15
Department B	Mar			2	5	8	13	20
Department C	Feb		4	6	7	9	12

<tbody>
</tbody>

Of course, the kick-off month may vary for each department and values from sheet 1 should accommodate according to the selected month on column B in sheet 2.

And within C2:I4 I have used this formula:

=IFERROR(IF(C$1>=$B2,INDEX(Sheet1!$B$2:$F$4,MATCH($A2,Sheet1!$A$2:$A$4,0),MONTH(C$1)-MONTH($B2)+1),""),"")
The formula above actually works great when departments are not repeated in sheet 1 but, what would happen if departments are repeated and I have to sum values from the same department and show the result on each cell in sheet 2?

I look forward to your kind help!

Thanks!