diff --git a/src/common/phase-helper.js b/src/common/phase-helper.js
index 8d12b6a..7e906f9 100644
--- a/src/common/phase-helper.js
+++ b/src/common/phase-helper.js
@@ -404,8 +404,18 @@ class ChallengePhaseHelper {
         ...phase,
         predecessor: resolvedPredecessor,
         description: phaseDefinition.description,
+        requestedScheduledStartDate: _.get(newPhase, "scheduledStartDate"),
         requestedScheduledEndDate: _.get(newPhase, "scheduledEndDate"),
       };
+      if (
+        _.isNil(updatedPhase.actualEndDate) &&
+        !_.isNil(updatedPhase.actualStartDate) &&
+        !_.isNil(updatedPhase.requestedScheduledStartDate)
+      ) {
+        updatedPhase.scheduledStartDate = moment(updatedPhase.requestedScheduledStartDate)
+          .toDate()
+          .toISOString();
+      }
       if (updatedPhase.name === "Post-Mortem") {
         updatedPhase.predecessor = "a93544bc-c165-4af4-b55e-18f3593b457a";
       }
@@ -414,7 +424,7 @@ class ChallengePhaseHelper {
       }
       if (_.isNil(updatedPhase.predecessor)) {
         let scheduledStartDate = _.defaultTo(
-          _.get(newPhase, "scheduledStartDate"),
+          updatedPhase.requestedScheduledStartDate,
           updatedPhase.scheduledStartDate
         );
         if (
@@ -485,7 +495,9 @@ class ChallengePhaseHelper {
       recalculateScheduledEndDate(phase);
     }
     validateRecalculatedPhaseSchedules(challengePhasesOrdered, updatedPhases, options);
-    return _.map(updatedPhases, (phase) => _.omit(phase, "requestedScheduledEndDate"));
+    return _.map(updatedPhases, (phase) =>
+      _.omit(phase, ["requestedScheduledStartDate", "requestedScheduledEndDate"])
+    );
   }
 
   handlePhasesAfterCancelling(phases) {
diff --git a/test/unit/phase-helper.test.js b/test/unit/phase-helper.test.js
index 635c94e..d5c9d7e 100644
--- a/test/unit/phase-helper.test.js
+++ b/test/unit/phase-helper.test.js
@@ -436,6 +436,53 @@ describe('phase helper unit tests', () => {
     updatedPhases[0].duration.should.equal(duration)
   })
 
+  it('allows started non-Design phase schedule to move earlier when duration is unchanged', async () => {
+    const registrationPhaseId = 'development-registration-phase'
+    const currentRegistrationStartDate = '2099-05-26T05:14:00.000Z'
+    const currentRegistrationEndDate = '2099-05-31T05:14:00.000Z'
+    const requestedRegistrationStartDate = '2099-05-25T05:14:00.000Z'
+    const requestedRegistrationEndDate = '2099-05-30T05:14:00.000Z'
+    const duration = 5 * 24 * 60 * 60
+
+    stubPhaseLookups(
+      [{ id: registrationPhaseId, name: 'Registration', description: 'Registration phase' }],
+      [{ phaseId: registrationPhaseId, defaultDuration: duration }]
+    )
+
+    const updatedPhases = await phaseHelper.populatePhasesForChallengeUpdate(
+      [
+        {
+          duration,
+          isOpen: true,
+          name: 'Registration',
+          phaseId: registrationPhaseId,
+          actualStartDate: requestedRegistrationStartDate,
+          scheduledStartDate: currentRegistrationStartDate,
+          scheduledEndDate: currentRegistrationEndDate
+        }
+      ],
+      [
+        {
+          duration,
+          phaseId: registrationPhaseId,
+          scheduledStartDate: requestedRegistrationStartDate,
+          scheduledEndDate: requestedRegistrationEndDate
+        }
+      ],
+      'timeline-template-id',
+      false,
+      {
+        allowActivePhaseShortening: false,
+        preventPhaseShortening: true
+      }
+    )
+
+    updatedPhases[0].actualStartDate.should.equal(requestedRegistrationStartDate)
+    updatedPhases[0].scheduledStartDate.should.equal(requestedRegistrationStartDate)
+    updatedPhases[0].scheduledEndDate.should.equal(requestedRegistrationEndDate)
+    updatedPhases[0].duration.should.equal(duration)
+  })
+
   it('allows active non-Design dependent phases to move earlier when duration is unchanged', async () => {
     const registrationPhaseId = 'development-registration-phase'
     const reviewPhaseId = 'development-review-phase'