Formula to return value a certain number of times a value occurs in another cell

[berimbau]

Hi all,

I have a data set that looks like this:

Invoice Month
A01 Jan
A02 Jan
A03 Feb
A04 Feb
A05 Feb
A06 Feb
A07 Mar
A08 Mar
A09 Mar

I need to put "Include" in another column the for the first two invoices raised in the month, and "Exclude" for every invoice raised in that month after the first two. The data will be sorted by date raised (so the first invoices appearing in the month are the ones that need to say "Include"). It would need to look like this:

Invoice Month Include/Exclude
A01 Jan Include
A02 Jan Include
A03 Feb Include
A04 Feb Include
A05 Feb Exclude
A06 Feb Exclude
A07 Mar Include
A08 Mar Include
A09 Mar Exclude

Can anyone think of a formula I could use to populate the include/exclude column?

Thanks
berimbau

 

[Momentman]

Like this maybe

Excel 2010
	A	B	C
1	Invoice	Month	Include/Exclude
2	A01	Jan	Include
3	A02	Jan	Include
4	A03	Feb	Include
5	A04	Feb	Include
6	A05	Feb	Exclude
7	A06	Feb	Exclude
8	A07	Mar	Include
9	A08	Mar	Include
10	A09	Mar	Exclude
Sheet2

Cell Formulas
Range	Formula
C2	=IF(COUNTIF($B$2:$B2,$B2)<=2, "Include", "Exclude")