diff --git a/members/admin/activityinvite_admin.py b/members/admin/activityinvite_admin.py
index 261f6e18..24deb6b0 100644
--- a/members/admin/activityinvite_admin.py
+++ b/members/admin/activityinvite_admin.py
@@ -1,10 +1,15 @@
 import codecs
+from datetime import timedelta
 from django import forms
 from django.contrib import admin
+from django.contrib import messages
+from django.contrib.admin.widgets import AdminDateWidget
+from django.db import transaction
 from django.db.models.functions import Lower
 from django.http import HttpResponse
+from django.shortcuts import render
 from django.urls import reverse
-from django.utils import timezone
+from django.utils import formats, timezone
 from django.utils.safestring import mark_safe
 from django.utils.html import escape
 from django.db.models import Exists, OuterRef
@@ -161,7 +166,7 @@ class Meta:
         "Du kan søge på forening, afdeling, aktivitet eller person. <br>Vandret dato-filter er for aktivitetens startdato."
     )
 
-    actions = ["export_csv_invitation_info"]
+    actions = ["export_csv_invitation_info", "extend_invitations"]
 
     form = ActivityInviteAdminForm
 
@@ -326,3 +331,69 @@ def export_csv_invitation_info(self, request, queryset):
         return response
 
     export_csv_invitation_info.short_description = "Exporter Invitationsinformationer"
+
+    def extend_invitations(modelAdmin, request, queryset):
+        class ExtendInvitationsForm(forms.Form):
+            expires = forms.DateField(
+                label="Udløber",
+                widget=AdminDateWidget(),
+                initial=timezone.now() + timedelta(days=14),
+            )
+
+        invitations = queryset
+
+        context = admin.site.each_context(request)
+        context["invitations"] = invitations
+        context["queryset"] = queryset
+
+        expires = timezone.now() + timedelta(days=14)
+        context["expires"] = expires
+
+        if request.method == "POST" and "expires" in request.POST:
+            extend_invitations_form = ExtendInvitationsForm(request.POST)
+            context["extend_invitations_form"] = extend_invitations_form
+
+            if extend_invitations_form.is_valid():
+                expires = extend_invitations_form.cleaned_data["expires"]
+
+                if expires < timezone.now().date():
+                    messages.error(
+                        request,
+                        "Fejl - den angivne udløbsdato er før dags dato.",
+                    )
+                    return
+
+                updated_invitations = 0
+                skipped_invitations = 0
+                try:
+                    with transaction.atomic():
+                        for invitation in invitations:
+                            if invitation.expire_dtm > expires:
+                                skipped_invitations += 1
+                                continue
+
+                            invitation.expire_dtm = expires
+                            invitation.save()
+                            updated_invitations += 1
+                except Exception as E:
+                    messages.error(
+                        request,
+                        f"Fejl - ingen invitationer blev forlænget! Følgende fejl opstod: {E=}",
+                    )
+                    return
+
+                status_text = f"{updated_invitations} invitationer blev forlænget til {formats.date_format(expires, 'DATE_FORMAT')}."
+                if skipped_invitations > 0:
+                    status_text += f"<br/>{skipped_invitations} invitationer blev sprunget over, da de allerede havde en senere udløbsdato."
+                messages.success(
+                    request,
+                    mark_safe(status_text),
+                )
+
+                return
+        else:
+            context["extend_invitations_form"] = ExtendInvitationsForm()
+
+        return render(request, "admin/extend_invitations.html", context)
+
+    extend_invitations.short_description = "Forlæng invitationer"
diff --git a/members/templates/admin/extend_invitations.html b/members/templates/admin/extend_invitations.html
new file mode 100644
index 00000000..2152a7ff
--- /dev/null
+++ b/members/templates/admin/extend_invitations.html
@@ -0,0 +1,73 @@
+{% extends "admin/base_site.html" %}
+{% load i18n admin_urls static admin_modify %}
+
+{% block extrahead %}{{ block.super }}
+<script type="text/javascript" src="{% url 'admin:jsi18n' %}"></script>
+<link rel="stylesheet" type="text/css" href="{% static "admin/css/forms.css" %}" />
+{{mass_confirmation_form.media}}
+{{ media }}
+{% endblock %}
+
+{% block extrastyle %}{{ block.super }}
+<script type="text/javascript" src="{% static "admin/js/core.js" %}"></script>
+<script type="text/javascript" src="{% static "admin/js/vendor/jquery/jquery.min.js" %}"></script>
+<script type="text/javascript" src="{% static "admin/js/jquery.init.js" %}"></script>
+{% endblock %}
+
+{% block breadcrumbs %}
+<div class="breadcrumbs">
+<a href="{% url 'admin:index' %}">{% trans 'Home' %}</a>
+&rsaquo; <a href="{% url 'admin:app_list' 'members' %}">Members</a>
+&rsaquo; <a href="">Personer</a>
+</div>
+{% endblock %}
+
+{% block content_title %}<h1>Forlæng valgte invitationer</h1>{% endblock %}
+
+{% block content %}
+<div id="content-main">
+  <form action="" method="post">
+    <p>Bemærk: Der sendes ikke ny mail</p>
+    <div>
+      <fieldset class="module aligned">
+        {% csrf_token %}
+        <input type="hidden" name="action" value="extend_invitations">
+        {% for obj in queryset %}
+          <input type="hidden" name="_selected_action" value="{{ obj.pk }}" />
+        {% endfor %}
+
+        <h2>Forlæng udløbsdato for invitation(er)</h2>
+        <div class="description">
+          <p>
+            Angiv ny dato:
+            <input type="date" name="expires" value="{{ expires|date:'Y-m-d' }}" required>
+          </p>
+        </div>
+
+        <h2>Deltagere</h2>
+        <div class="description">
+          <p>Forlæng invitation for følgende ({{ persons.count }}) personer:</p>
+          <ul>
+              {% for invitation in invitations %}
+              <li>{{ invitation.person.name }}</li>
+              {% endfor %}
+          </ul>
+        </div>
+
+        {% for field in mass_confirmation_form %}
+          <div class="form-row field-{{ field.name }}">
+              {{ field.errors }}
+              {{ field.label_tag }} {{ field }}
+          </div>
+        {% endfor %}
+
+        <br>
+        <div class="submit-row">
+          <p class="deletelink-box"><a href="../" class="deletelink">Fortryd</a></p>
+          <input class="default" name="" type="submit" value="Forlæng valgte invitationer">
+        </div>
+      </fieldset>
+    </div>
+  </form>
+</div>
+{% endblock %}