Since using character data tends to slow things down, maybe this:
SELECT DATEADD(DAY, b.Fiscal_Year_End_Day_Nbr - 1,
DATEADD(MONTH, b.Fiscal_Year_End_Month_Nbr - 1,
DATEADD(YEAR, b.Fiscal_Year_End_Year_Nbr - 1900, 0)))
FROM (
SELECT 2015 AS Fiscal_Year_End_Year_Nbr, 11 AS Fiscal_Year_End_Month_Nbr, 23 AS Fiscal_Year_End_Day_Nbr UNION ALL
SELECT 2015, 12, 16
) AS b
SQL DBA,SQL Server MVP(07, 08, 09) A socialist is someone who will give you the shirt off *someone else's* back.