I also tried the following: CASE WHEN EXTRACT(YEAR FROM {accountingperiod.enddate}) < EXTRACT(YEAR FROM SYSDATE) -2 THEN CASE WHEN EXTRACT(MONTH FROM ({accountingperiod.enddate}) < EXTRACT(MONTH FROM SYSDATE) THEN NVL({debitamount},0) - NVL({creditamount},0) ELSE 0 END ELSE 0 END