diff --git a/lmsege/lms/admin.py b/lmsege/lms/admin.py
index 4ea4fe5..9c74992 100644
--- a/lmsege/lms/admin.py
+++ b/lmsege/lms/admin.py
@@ -107,6 +107,11 @@ class SubmissionAdmin(ModelAdmin):
     search_fields = ('student__username', 'assignment__title')
     inlines = [AnswerInline]
 
+    def get_readonly_fields(self, request, obj=None):
+        if obj:
+            return ('assignment', 'student', 'is_time_expired', 'is_late', 'started_at', 'submitted_at')
+        return ('is_time_expired', 'is_late', 'started_at', 'submitted_at')
+
     def get_queryset(self, request):
         qs = super().get_queryset(request)
         if request.user.is_superuser or request.user.role == 'ADMIN':