Start date of Financial Year for a date

The function calculates start day of financial year when a date is given as a parameter

CREATE OR REPLACE FUNCTION FINYEAR_FROM_DATE (A_DATE IN DATE)
RETURN CHAR
IS
AA CHAR (10);
NN NUMBER (8);
BB CHAR (8);
BEGIN
BB := TO_CHAR (A_DATE, ‘yyyy’) || TO_CHAR (A_DATE, ‘yyyy’);
NN := BB;

IF TO_CHAR (A_DATE, ‘mm’) < ’04’
THEN
NN := NN – 10000;
ELSE
NN := NN + 1;
END IF;

BB := LTRIM (RTRIM (TO_CHAR (NN, ‘00000000’)));
–aa := substr(bb,1,4)||substr(bb,7,2);
AA := ’01/04/’ || SUBSTR (BB, 1, 4);
RETURN (AA);
END;