Sub Macro1()
Dim i
Application.ScreenUpdating = False
Sheets("MODELE").Select
For i = 1 To 12
Sheets("MODELE").Copy After:=Sheets(i)
Sheets(i + 1).Name = Format(30 * i, "mmmm") & " " & Year(Date)
Worksheets(i + 1).Range("A1") = CDate(DateSerial(Year(Date), i, 1))
Next
End Sub