Hi Evan.

Put a command button on a form and put this code in the click event:
Code:
Private Sub Command1_Click()
    Dim myDate As Date
    
    myDate = #12/10/1999#
    
    If DateDiff("d", myDate, Now) > 90 Then
        MsgBox "Date Difference is more than 3 months"
    Else
        MsgBox "Date Difference is less than 3 months"
    End If
End Sub
All the best.