Option Explicit
Sub test()
Dim rep As String, nom As String, wb As Workbook
rep = ThisWorkbook.Path & "\Facture\"
nom = Format(Month(Date), "00") & "_" & Year(Date) & ".xls"
If Dir(rep, vbDirectory) = "" Then
MkDir (rep)
Set wb = Workbooks.Add
wb.SaveAs rep & nom
Else
If ClasseurExiste(rep & nom) Is Nothing Then Set wb = Workbooks.Open(rep & nom)
End If
Workbooks("Factureteste.xlsm").Sheets("Facture").Copy before:=wb.Sheets(1)
End Sub
Function ClasseurExiste(c As String) As Workbook
On Error Resume Next
Set ClasseurExiste = Workbooks(c)
End Function