SQL> create table t ( id int, income int, s date, e date );

Table created.

SQL>
SQL> insert into t values (1,2000,date '2016-02-01', date '2016-05-31');

1 row created.

SQL> insert into t values (2,1000,date '2016-01-01', date '2016-04-30');

1 row created.

SQL>
SQL> select t.id,t.income,add_months(s,column_value-1) d
  2  from t,
  3    table(
  4       cast(multiset(select rownum r from   dual connect by level <= round(months_between(t.e,t.s)) )
  5         as sys.ODCINUMBERLIST));

        ID     INCOME D
---------- ---------- ---------
         1       2000 01-FEB-16
         1       2000 01-MAR-16
         1       2000 01-APR-16
         1       2000 01-MAY-16
         2       1000 01-JAN-16
         2       1000 01-FEB-16
         2       1000 01-MAR-16
         2       1000 01-APR-16

8 rows selected.