Private Sub Workbook_Open()
'replace sheet1 with correct sheet to filter
Sheet1.Select
'replace Range("A1") and Range("A$1") with correct column to filter
Range("A1").Select
Selection.AutoFilter
Range("$A$1").AutoFilter Field:=1, Criteria1:=">=" & VBA.Format(DateAdd("m", -1, Date), "m/d/yyyy"), Operator _
:=xlAnd, Criteria2:="<" & VBA.Format(Date, "m/d/yyyy"), SubField:=0
End Sub