diff --git a/docs/using-branches/syncing-merging.md b/docs/using-branches/syncing-merging.md
index af3c8f9..3c7d0cd 100644
--- a/docs/using-branches/syncing-merging.md
+++ b/docs/using-branches/syncing-merging.md
@@ -6,6 +6,9 @@ Synchronizing a branch replicates all recent changes from main into the branch.
 
 To synchronize a branch, click the "Sync" button. (If this button is not visible, verify that the branch status shows "ready" and that you have permission to synchronize the branch.)
 
+!!! warning
+    A branch must be synchronized frequently enough to avoid exceeding NetBox's configured [changelog retention period](https://netboxlabs.com/docs/netbox/en/stable/configuration/miscellaneous/#changelog_retention) (which defaults to 90 days). This is to protect against data loss when replicating changes from main. A branch whose `last_sync` time exceeds the configured retention window can no longer be synced.
+
 While a branch is being synchronized, its status will show "synchronizing."
 
 !!! tip
diff --git a/netbox_branching/models/branches.py b/netbox_branching/models/branches.py
index 5cc2a2a..6ace090 100644
--- a/netbox_branching/models/branches.py
+++ b/netbox_branching/models/branches.py
@@ -1,6 +1,7 @@
 import logging
 import random
 import string
+from datetime import timedelta
 from functools import cached_property, partial
 
 from django.conf import settings
@@ -15,6 +16,7 @@
 from django.utils.translation import gettext_lazy as _
 
 from core.models import ObjectChange as ObjectChange_
+from netbox.config import get_config
 from netbox.context import current_request
 from netbox.context_managers import event_tracking
 from netbox.models import PrimaryModel
@@ -121,7 +123,7 @@ def schema_name(self):
     def connection_name(self):
         return f'schema_{self.schema_name}'
 
-    @cached_property
+    @property
     def synced_time(self):
         return self.last_sync or self.created
 
@@ -240,6 +242,16 @@ def get_event_history(self):
             last_time = event.time
         return history
 
+    @property
+    def is_stale(self):
+        """
+        Indicates whether the branch is too far out of date to be synced.
+        """
+        if not (changelog_retention := get_config().CHANGELOG_RETENTION):
+            # Changelog retention is disabled
+            return False
+        return self.synced_time < timezone.now() - timedelta(days=changelog_retention)
+
     def sync(self, user, commit=True):
         """
         Apply changes from the main schema onto the Branch's schema.
@@ -249,6 +261,8 @@ def sync(self, user, commit=True):
 
         if not self.ready:
             raise Exception(f"Branch {self} is not ready to sync")
+        if self.is_stale:
+            raise Exception(f"Branch {self} is stale and can no longer be synced")
 
         # Emit pre-sync signal
         pre_sync.send(sender=self.__class__, branch=self, user=user)
diff --git a/netbox_branching/tables/tables.py b/netbox_branching/tables/tables.py
index b1165b3..8d90a59 100644
--- a/netbox_branching/tables/tables.py
+++ b/netbox_branching/tables/tables.py
@@ -56,8 +56,16 @@ class BranchTable(NetBoxTable):
         verbose_name=_('Name'),
         linkify=True
     )
+    is_active = columns.BooleanColumn(
+        verbose_name=_('Active')
+    )
     status = columns.ChoiceFieldColumn(
-        verbose_name=_('Status'),
+        verbose_name=_('Status')
+    )
+    is_stale = columns.BooleanColumn(
+        true_mark=mark_safe('<span class="text-danger"><i class="mdi mdi-alert-circle"></i></span>'),
+        false_mark=None,
+        verbose_name=_('Stale')
     )
     conflicts = ConflictsColumn(
         verbose_name=_('Conflicts')
@@ -72,11 +80,11 @@ class BranchTable(NetBoxTable):
     class Meta(NetBoxTable.Meta):
         model = Branch
         fields = (
-            'pk', 'id', 'name', 'is_active', 'status', 'conflicts', 'schema_id', 'description', 'owner', 'tags',
-            'created', 'last_updated',
+            'pk', 'id', 'name', 'is_active', 'status', 'is_stale', 'conflicts', 'schema_id', 'description', 'owner',
+            'tags', 'created', 'last_updated',
         )
         default_columns = (
-            'pk', 'name', 'is_active', 'status', 'owner', 'conflicts', 'schema_id', 'description',
+            'pk', 'name', 'is_active', 'status', 'is_stale', 'owner', 'conflicts', 'schema_id', 'description',
         )
 
     def render_is_active(self, value):
diff --git a/netbox_branching/templates/netbox_branching/branch.html b/netbox_branching/templates/netbox_branching/branch.html
index 75eff0c..08705d8 100644
--- a/netbox_branching/templates/netbox_branching/branch.html
+++ b/netbox_branching/templates/netbox_branching/branch.html
@@ -82,11 +82,24 @@ <h5 class="card-header">{% trans "Branch" %}</h5>
           </tr>
           <tr>
             <th scope="row">{% trans "Last synced" %}</th>
-            <td>{{ object.synced_time|isodatetime }}</td>
+            <td>
+              {{ object.synced_time|isodatetime }}
+              {% if object.is_stale %}
+                <span class="text-danger" title="{% trans "Branch is stale and can no longer be synced" %}">
+                  <i class="mdi mdi-alert-circle"></i>
+                </span>
+              {% endif %}
+              <div class="small text-muted">{{ object.synced_time|timesince }} {% trans "ago" %}</div>
+            </td>
           </tr>
           <tr>
             <th scope="row">{% trans "Last activity" %}</th>
-            <td>{{ latest_change.time|isodatetime|placeholder }}</td>
+            <td>
+              {{ latest_change.time|isodatetime|placeholder }}
+              {% if latest_change %}
+                <div class="small text-muted">{{ latest_change.time|timesince }} {% trans "ago" %}</div>
+              {% endif %}
+            </td>
           </tr>
           <tr>
             <th scope="row">{% trans "Conflicts" %}</th>
diff --git a/netbox_branching/templates/netbox_branching/buttons/branch_sync.html b/netbox_branching/templates/netbox_branching/buttons/branch_sync.html
index fcf21bb..dc0e422 100644
--- a/netbox_branching/templates/netbox_branching/buttons/branch_sync.html
+++ b/netbox_branching/templates/netbox_branching/buttons/branch_sync.html
@@ -1,5 +1,5 @@
 {% load i18n %}
-{% if perms.netbox_branching.sync_branch %}
+{% if perms.netbox_branching.sync_branch and not branch.is_stale %}
   <a href="{% url 'plugins:netbox_branching:branch_sync' pk=branch.pk %}" class="btn btn-primary">
     <i class="mdi mdi-sync"></i> {% trans "Sync" %}
   </a>
diff --git a/netbox_branching/tests/test_branches.py b/netbox_branching/tests/test_branches.py
index 3bb263b..66a9a6b 100644
--- a/netbox_branching/tests/test_branches.py
+++ b/netbox_branching/tests/test_branches.py
@@ -1,8 +1,10 @@
 import re
+from datetime import timedelta
 
 from django.core.exceptions import ValidationError
 from django.db import connection
 from django.test import TransactionTestCase, override_settings
+from django.utils import timezone
 
 from netbox_branching.choices import BranchStatusChoices
 from netbox_branching.constants import MAIN_SCHEMA
@@ -125,3 +127,18 @@ def test_max_branches(self):
         branch = Branch(name='Branch 4')
         with self.assertRaises(ValidationError):
             branch.full_clean()
+
+    @override_settings(CHANGELOG_RETENTION=10)
+    def test_is_stale(self):
+        branch = Branch(name='Branch 1')
+        branch.save(provision=False)
+
+        # Set creation time to 9 days in the past
+        branch.last_sync = timezone.now() - timedelta(days=9)
+        branch.save()
+        self.assertFalse(branch.is_stale)
+
+        # Set creation time to 11 days in the past
+        branch.last_sync = timezone.now() - timedelta(days=11)
+        branch.save()
+        self.assertTrue(branch.is_stale)