First day of month, last day of month, rolling down column

Try this...

Enter the first few dates in A1:A3...

A1 = 1/1/2016
A2 = 2/1/2016
A3 = 3/1/2016

Enter this formula in B1:

=EOMONTH(A1,0)

Format as Date then copy down to B3.

Now, select A2:B3 then drag down the column as needed.

Try these and copy down:

Excel 2016 (Windows) 32 bit

	A	B
1	=EOMONTH($D$1,ROWS($A$1:A1)-2)+1	=EOMONTH($D$1,ROWS($A$1:A1)-1)

Sheet: Sheet2

where D1 contains your start date.

My beginning of the month is the same formula as AliGW (only with different references). My end of the month formula is different

	A	B	C	D	E
1	14/04/2016		Beginning of Month	End month
2		=EOMONTH($A$1,ROWS($1:1)-2)+1	01/04/2016	30/04/2016	=EOMONTH(C2,0)
3			01/05/2016	31/05/2016
4			01/06/2016	30/06/2016
5			01/07/2016	31/07/2016
6			01/08/2016	31/08/2016
7			01/09/2016	30/09/2016