Auto populate new column with month numbers from dates given in a cell?

In Excel I have cells in column C that have dates showing every month from the 05.12.13 through to 05.04.15 the fifth day of every month being the deadline date. I wanted to populate another column next to these dates as column D as :

05.12.13 = month 8
05.01.14 = month 9
05.02.14 = month 10
05.03.14 = month 11
05.04.14 = month 12
05.05.14 = month 1
eg...all the way to..
05.10.14 = month 6
05.12.14 = month 8
05.04.15 = month 12

how do I make the new column D populate with these month numbers in a macro??

You don't need a macro, just add this formula

=MONTH(EOMONTH(C1,8))

and copy down