diff --git a/abonapp/templates/abonapp/group_tariffs.html b/abonapp/templates/abonapp/group_tariffs.html
index e03547d..ca079ba 100644
--- a/abonapp/templates/abonapp/group_tariffs.html
+++ b/abonapp/templates/abonapp/group_tariffs.html
@@ -32,4 +32,4 @@
             <input type="submit" class="btn btn-primary" value="{% trans 'Save' %}"> <input type="reset" class="btn btn-default" value="{% trans 'Reset' %}">
         </div>
     </form>
-{% endblock %}
\ No newline at end of file
+{% endblock %}
diff --git a/abonapp/views.py b/abonapp/views.py
index b30d403..4d1610b 100644
--- a/abonapp/views.py
+++ b/abonapp/views.py
@@ -633,9 +633,16 @@ def chgroup_tariff(request, gid):
     if not request.user.has_perm('group_app.change_group', grp):
         raise PermissionDenied
     if request.method == 'POST':
-        tr = request.POST.getlist('tr')
-        grp.tariff_set.clear()
-        grp.tariff_set.add(*tr)
+        ma = frozenset(t.id for t in grp.tariff_set.all())
+        mb = frozenset(map(int, request.POST.getlist('tr')))
+        sub = ma - mb
+        add = mb - ma
+        grp.tariff_set.remove(*sub)
+        grp.tariff_set.add(*add)
+        models.Abon.objects.filter(
+            group=grp,
+            last_connected_tariff__in=sub
+        ).update(last_connected_tariff=None)
         messages.success(request, _('Successfully saved'))
         return redirect('abonapp:ch_group_tariff', gid)
     tariffs = Tariff.objects.all()