How to Check Date Format using Macro Enetred by User ....

This will trap the specific error

Private Sub CommandButton2_Click()
Dim iMonth As Integer
    
    On Error GoTo Invalid
    iMonth = Day(Range("B3").Value)
    If iMonth > 12 Then
        MsgBox "Date Error"
    End If
    On Error GoTo 0
    Exit Sub
    
Invalid:
    MsgBox "Invalid date entry"
    On Error GoTo 0
    
End Sub

but bear in mind that it can only detect a date error for dates entered after the 12th of each month...