I am trying to set up a function so that whether I pass a blank cell or do not even select a cell for the argument it returns the function I am looking for. Here is my code: Function FinancialsAge(FirstBirthday As Date, BeginningDate As Date, Optional Second Birthday As Variant) As String If IsMissing(SecondBirthday) = True Or SecondBirthday = vbNullString Then FinancialsAge = Year(BeginningDate - FirstBirthday) - 1900 ElseIf SecondBirthday Then FinancialsAge = (Year(BeginningDate - FirstBirthday) - 1900) & "/" & (Year(BeginningDate - SecondBirthday) - 1900) End If End Function This code works fine as long as I select a blank cell for the third argument but when I leave the third argument out I get a "#Value!" error in the cell. Anyway to do this in Excel VBA so that the function works under both circumstances? Thanks,