Public Function IsLeapYear(ByVal vzInput As Variant) As Boolean
Dim nYear As Integer
If VarType(vzInput) = vbDate Then
nYear = DatePart("YYYY", vzInput)
ElseIf IsNumeric(vzInput) Then
nYear = vzInput
Else
Exit Function
End If
IsLeapYear = IsDate(nYear & "-02-29")
End Function