diff --git a/backend/app/models.py b/backend/app/models.py
index cedd5c4..a600007 100644
--- a/backend/app/models.py
+++ b/backend/app/models.py
@@ -1,5 +1,5 @@
 from .extensions import db
-from datetime import datetime
+from datetime import datetime, date
 
 class Project(db.Model):
     __tablename__ = 'projects'
@@ -42,12 +42,22 @@ class Deliverable(db.Model):
     status     = db.Column(db.String(20), nullable=False, default='upcoming')
     created_at = db.Column(db.DateTime, default=datetime.utcnow)
 
+    def effective_status(self):
+        """
+        Returns 'overdue' if the due date has passed and the deliverable
+        has not been marked completed. Completed deliverables are never
+        auto-downgraded regardless of date.
+        """
+        if self.status != 'completed' and self.due_date < date.today():
+            return 'overdue'
+        return self.status
+
     def to_dict(self):
         return {
             'id':         self.id,
             'project_id': self.project_id,
             'title':      self.title,
             'due_date':   self.due_date.isoformat() if self.due_date else None,
-            'status':     self.status,
+            'status':     self.effective_status(),
             'created_at': self.created_at.isoformat() if self.created_at else None,
         }