Function ProchPériode(ByVal Période As String, ByVal Catég As String) As String
Dim N As Long
N = Left$(Période, 4) * 12 - 1 + Right$(Période, 2) + Choose(Asc(Catég) - 64, 1, 3, 6, 12)
ProchPériode = N \ 12 & "M" & Format(N Mod 12 + 1, "00")
End Function