Public Function Ecart(DateDeb As Date, DateFin As Date) As String
Dim D As Long
D = DateDiff('m', DateDeb, DateFin) + 1
If Day(DateDeb) > 1 Or DateAdd('m', D, DateDeb) - 1 <> DateFin Then
D = DateDiff('d', DateDeb, DateFin)
Ecart = D & ' jours'
Else
Ecart = D & ' mois'
End If
End Function