diff --git a/src/addons/mod/assign/components/submission/submission.ts b/src/addons/mod/assign/components/submission/submission.ts
index c045ff47a..0164e3c32 100644
--- a/src/addons/mod/assign/components/submission/submission.ts
+++ b/src/addons/mod/assign/components/submission/submission.ts
@@ -218,14 +218,19 @@ export class AddonModAssignSubmissionComponent implements OnInit, OnDestroy, Can
 
         const time = CoreTimeUtils.timestamp();
         const timeLimitEnabled = this.assign.timelimit && submissionStarted;
-        const dueDateReached = this.assign.duedate > 0 && this.assign.duedate - time <= 0;
+
+        // Define duedate as latest between due date and extension - which is a possibility...
+        const extensionDuedate = response.lastattempt?.extensionduedate;
+        const duedate = extensionDuedate ? Math.max(this.assign.duedate, extensionDuedate) : this.assign.duedate;
+        const dueDateReached = duedate > 0 && duedate - time <= 0;
+
         const timeLimitEnabledBeforeDueDate = timeLimitEnabled && !dueDateReached;
 
         if (this.userSubmission && this.userSubmission.status === AddonModAssignSubmissionStatusValues.SUBMITTED) {
             // Submitted, display the relevant early/late message.
             const lateCalculation = this.userSubmission.timemodified -
                 (timeLimitEnabledBeforeDueDate ? this.userSubmission.timecreated : 0);
-            const lateThreshold = timeLimitEnabledBeforeDueDate ? this.assign.timelimit || 0 : this.assign.duedate;
+            const lateThreshold = timeLimitEnabledBeforeDueDate ? this.assign.timelimit || 0 : duedate;
             const earlyString = timeLimitEnabledBeforeDueDate ? 'submittedundertime' : 'submittedearly';
             const lateString = timeLimitEnabledBeforeDueDate ? 'submittedovertime' : 'submittedlate';
             const onTime = lateCalculation <= lateThreshold;
@@ -244,7 +249,7 @@ export class AddonModAssignSubmissionComponent implements OnInit, OnDestroy, Can
             const submissionsEnabled = response.lastattempt?.submissionsenabled || response.gradingsummary?.submissionsenabled;
             this.timeRemaining = Translate.instant(
                 'addon.mod_assign.' + (submissionsEnabled ? 'overdue' : 'duedatereached'),
-                { $a: CoreTime.formatTime(time - this.assign.duedate) },
+                { $a: CoreTime.formatTime(time - duedate) },
             );
             this.timeRemainingClass = 'overdue';
             this.timeLimitFinished = true;
@@ -262,7 +267,7 @@ export class AddonModAssignSubmissionComponent implements OnInit, OnDestroy, Can
         }
 
         // Assignment is not overdue, and no submission has been made. Just display the due date.
-        this.timeRemaining = CoreTime.formatTime(this.assign.duedate - time);
+        this.timeRemaining = CoreTime.formatTime(duedate - time);
         this.timeRemainingClass = 'timeremaining';
     }