diff --git a/openstackclient/compute/v2/server.py b/openstackclient/compute/v2/server.py
index a09fd44d0a..9180361dee 100644
--- a/openstackclient/compute/v2/server.py
+++ b/openstackclient/compute/v2/server.py
@@ -2204,7 +2204,7 @@ class ListServer(command.Lister):
                 )
                 raise exceptions.CommandError(msg)
 
-            search_opts['tags'] = parsed_args.tags
+            search_opts['tags'] = ','.join(parsed_args.tags)
 
         if parsed_args.not_tags:
             if compute_client.api_version < api_versions.APIVersion('2.26'):
@@ -2214,7 +2214,7 @@ class ListServer(command.Lister):
                 )
                 raise exceptions.CommandError(msg)
 
-            search_opts['not-tags'] = parsed_args.not_tags
+            search_opts['not-tags'] = ','.join(parsed_args.not_tags)
 
         if parsed_args.locked:
             if compute_client.api_version < api_versions.APIVersion('2.73'):
diff --git a/openstackclient/tests/unit/compute/v2/test_server.py b/openstackclient/tests/unit/compute/v2/test_server.py
index 57840cb076..2f83fa2bd3 100644
--- a/openstackclient/tests/unit/compute/v2/test_server.py
+++ b/openstackclient/tests/unit/compute/v2/test_server.py
@@ -4269,7 +4269,7 @@ class TestServerList(TestServer):
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
         columns, data = self.cmd.take_action(parsed_args)
 
-        self.search_opts['tags'] = ['tag1', 'tag2']
+        self.search_opts['tags'] = 'tag1,tag2'
 
         self.servers_mock.list.assert_called_with(**self.kwargs)
 
@@ -4312,7 +4312,7 @@ class TestServerList(TestServer):
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
         columns, data = self.cmd.take_action(parsed_args)
 
-        self.search_opts['not-tags'] = ['tag1', 'tag2']
+        self.search_opts['not-tags'] = 'tag1,tag2'
 
         self.servers_mock.list.assert_called_with(**self.kwargs)
 
diff --git a/releasenotes/notes/bug-1946816-7665858605453578.yaml b/releasenotes/notes/bug-1946816-7665858605453578.yaml
new file mode 100644
index 0000000000..f9e8406a9e
--- /dev/null
+++ b/releasenotes/notes/bug-1946816-7665858605453578.yaml
@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Filtering servers by tags (``server list --tag``,
+    ``server list --not-tag``) now works correctly.
+    [Bug `1946816 <https://bugs.launchpad.net/bugs/1946816>`_]