diff --git a/SAS/ResourceAssignment/ResourceAssigner/lib/assignment.py b/SAS/ResourceAssignment/ResourceAssigner/lib/assignment.py
index 62c53beb54282b17d0e64e7c072de3ef66d7886e..f78e06beb3e3de7a3a0201ccdcaf06102fa11c5f 100755
--- a/SAS/ResourceAssignment/ResourceAssigner/lib/assignment.py
+++ b/SAS/ResourceAssignment/ResourceAssigner/lib/assignment.py
@@ -136,12 +136,7 @@ class ResourceAssigner():
         clusterName = 'CEP4' if clusterIsCEP4 else 'CEP2'
 
         if clusterIsCEP4:
-            try:
-                startTime = datetime.strptime(mainParset.getString('Observation.startTime'), '%Y-%m-%d %H:%M:%S')
-                endTime = datetime.strptime(mainParset.getString('Observation.stopTime'), '%Y-%m-%d %H:%M:%S')
-            except ValueError:
-                logger.warning('cannot parse for start/end time from specification for otdb_id=%s. searching for sane defaults...', (otdb_id, ))
-
+            def applySaneStartEndTime():
                 startTime = datetime.utcnow() + timedelta(minutes=1)
 
                 maxPredecessorEndTime = self.getMaxPredecessorEndTime(specification_tree)
@@ -163,6 +158,17 @@ class ResourceAssigner():
                 except Exception as e:
                     logger.error(e)
 
+                return startTime, endTime
+
+            try:
+                startTime = datetime.strptime(mainParset.getString('Observation.startTime'), '%Y-%m-%d %H:%M:%S')
+                endTime = datetime.strptime(mainParset.getString('Observation.stopTime'), '%Y-%m-%d %H:%M:%S')
+                if startTime < datetime.utcnow():
+                    startTime, endTime = applySaneStartEndTime()
+            except ValueError:
+                logger.warning('cannot parse for start/end time from specification for otdb_id=%s. searching for sane defaults...', otdb_id)
+                startTime, endTime = applySaneStartEndTime()
+
             try:
                 # fix for MoM bug introduced before NV's holiday
                 # MoM sets ProcessingCluster.clusterName to CEP2 even when inputxml says CEP4