IsWeekDay

Function FESTIVO(Data As Date) As Boolean
Dim Anno As Integer, DayMax As Date, DayMin As Date
Anno = Year(Data)
If WeekDay(Data) = 1 Then
FESTIVO = True
Exit Function
End If

If Day(Data) = 1 And (Month(Data) = 1 Or Month(Data) = 5 Or Month(Data) = 11) Or _
Day(Data) = 6 And Month(Data) = 1 Or Day(Data) = 25 And (Month(Data) = 4 Or _
Month(Data) = 12) Or Day(Data) = 15 And Month(Data) = 8 Or (Day(Data) = 8 Or _
Day(Data) = 26) And Month(Data) = 12 Then

FESTIVO = True
Exit Function
End If

FESTIVO = False

End Function