Sure, this code adds one month to the first day entered and assigns it to the second date field. To modify this to, say two months, change the 1 to a 2.
Since you're new to database design, I should tell you that in most cases a calculated field, like the data in txtSecondDate, shouldn't be stored in a table, but rather simply re-calculated, like it is here, whenever you need it.
Private Sub txtFirstDate_AfterUpdate()
If Not IsNull(Me.txtFirstDate) Then
Me.txtSecondDate = DateAdd("m", 1, Me.txtFirstDate)
Me.txtSecondDate = Null
Hope this helps!
The problem with making anything foolproof...is that fools are so darn ingenious!
All posts/responses based on Access 2003/2007