Filter on value in another row
Based on my understanding of your needs, you could use a Common Table Expression (CTE) to achieve this. Define your main query within the CTE and then do a JOIN on a second SELECT which calculates the total per JobID:

WITH results AS
(
    SELECT ID, 
           JobID, 
           NAME, 
           ORDERNUM, 
           STARTAFTER, 
           FINISHBEFORE, 
           START_OFFSET_MINS, 
           TOTAL_MINUTES_REQ - 
           (SELECT COALESCE(
                     SUM(TABLE_PROCESSTIMES.END_TIME - 
                         TABLE_PROCESSTIMES.START_TIME) / 60, 0) 
              FROM TABLE_PROCESSTIMES 
             WHERE TABLE_PROCESSTIMES.PROCESSID = TABLE_PROCESSES.ID 
               AND TABLE_PROCESSTIMES.START_DATE &lt;= '24.04.2018'
           ) AS STILL_REQUIRED 
      FROM TABLE_PROCESSES
)
SELECT x.*
  FROM results x
  JOIN (SELECT JobID, SUM(STILL_REQUIRED) AS STILL_REQUIRED
          FROM results
      GROUP BY JobID) y
    ON x.JobID = y.JobID
 WHERE y.STILL_REQUIRED &gt; 0