This will work:

DECLARE @ThisYear INT,

@ThisMonth INT;

SET @ThisYear = 2013;

SET @ThisMonth = 2;

SELECT

DATEADD(MONTH, @ThisMonth - 1, DATEADD(YEAR, @ThisYear - 1900, CAST('19000101' AS DATETIME))) BOM,

DATEADD(DAY, -1, DATEADD(MONTH, @ThisMonth, DATEADD(YEAR, @ThisYear - 1900, CAST('19000101' AS DATETIME)))) EOM