PS Query service calc expression

Hi, a question re an expression added to calculate the total service between start and end dates.
Includes the expression SUM((TO_DATE(NVL(A.EFFDT_END_WA, SYSDATE),'YYYY-MM-DD')-TO_DATE(A.EFFDT_START_WA,'YYYY-MM-DD'))/365)...works fine Seeking some advice re adding to this expression so that employees that have an end date greater than system date have the service calculated to SYSDATE date only eg A.EFFDT_END_WA > SYSDATE, THEN SYSDATE. Thanks