Sub test()
Dim Debut As Date, Fin As Date, LigEcrit As Integer, NbLigBase As Integer
Set F1 = Sheets("Base")
Fin = "24/01/2016" 'FinP 'fin de periode
Debut = "07/12/2015"
NbLigBase = F1.Range("A65000").End(xlUp).Row
zz = WorksheetFunction.CountIf(F1.Range("A2:A" & NbLigBase), ">=" & Debut)
yy = WorksheetFunction.CountIf(F1.Range("A2:A" & NbLigBase), ">=" & CLng(Debut))
MsgBox zz & vbLf & yy
End Sub