SQL script to find if date is a part of Leap Year or Not - 1

There are times when we wish to check the date that we are dealing with belongs to the leap year or not. 
I came across such a situation and ended up designing a function for it. 
This function takes the date as an input and returns BIT value depending on whether year of the 
date passed qualifies as a leap year of not.

The logic that I used here is given below

• Fetch the year of the date passed.
• Using it form the first and last day of year
• Calculate the difference between FirstDayOfYear and LastDayOfYear

CREATE FUNCTION udf_IsLeapyear(@InDate DATETIME)RETURNS BIT
AS
BEGIN

   DECLARE @YEAR VARCHAR(10),
           @DATE VARCHAR(20)= '-12-31'

   SELECT @YEAR = CONVERT(VARCHAR(10),DATEPART(YEAR,@InDate))
   RETURN
   (
    SELECT
       CASE
           WHEN DATEDIFF(DAY,DATEADD(YEAR,-1,CONVERT(DATE,@YEAR+@DATE)),CONVERT(DATE,@YEAR+@DATE))=366 THEN 1
           ELSE 0
       END
    )
END