>>nMonths = (year(dDate2)*12 + month(ddate2)) - (year(dDate1)*12 + month(dDate1)) + 1

>Let me give you an example. (a date always have to be the first of a given month)
>
>So if:
>
>Date1 is April 2000
>Date2 is May 1999
>
>I would like in this case to be able to validate that the specified period covers one year (12 months).

The calculate at the top works for that case try it out.