Bonjour,
Pour les curieux !...
Option Explicit
Public Function fnCalculation(txt As String, txt2 As String) As String
Dim dt As Date, dt2 As Date, x As Long
fnCalculation = ""
If txt = "" Or txt2 = "" Then Exit Function
dt = DateValue(txt & "-" & 1)
Select Case txt2
Case "NULL":
x = DateDiff("yyyy", dt, Date)
If x >= 1 Then fnCalculation = "X"
Case Else:
dt2 = DateValue(txt2 & "-" & 1)
x = DateDiff("yyyy", dt, dt2)
If x <= 5 Then fnCalculation = "X"
End Select
End Function