Sub Incrémentation()
Dim MaDate As Date, I As Integer, Mensualités As Integer, PremLigne As Integer, Colonne As Integer
If Selection.Count <> 1 Then Exit Sub
MaDate = CDate(Selection)
PremLigne = Selection.Row
Colonne = Selection.Column
Mensualités = InputBox("Nombre de mois ?", "Mensualités")
For I = PremLigne + 1 To Mensualités + PremLigne - 1
Cells(I, Colonne) = DateAdd("m", 1, Cells(I - 1, Colonne))
Next
Cells(PremLigne, Colonne).Select
End Sub