diff --git a/novem/cli/setup.py b/novem/cli/setup.py
index 9d88b35..2c17edb 100644
--- a/novem/cli/setup.py
+++ b/novem/cli/setup.py
@@ -226,7 +226,7 @@ def setup(raw_args: Any = None) -> Tuple[Any, Dict[str, str]]:
         required=False,
         default="",
         nargs="?",
-        help="select a tag to operate on (fav, like, ignore, wip, archived, or +usertag), "
+        help="select a tag to operate on (fav, like, ignore, wip, archived, +usertag, or =categorytag), "
         "no parameter will list all current tags",
     )
 
diff --git a/novem/cli/vis.py b/novem/cli/vis.py
index b9c5837..90281eb 100644
--- a/novem/cli/vis.py
+++ b/novem/cli/vis.py
@@ -348,6 +348,9 @@ def tag_pretty_print(iplist: List[Dict[str, str]], striped: bool = False) -> Non
         elif tag_name.startswith("+"):
             p["summary"] = "User-defined tag"
             p["type"] = "user"
+        elif tag_name.startswith("="):
+            p["summary"] = "Category tag"
+            p["type"] = "category"
         else:
             p["summary"] = "Custom tag"
             p["type"] = "custom"
diff --git a/novem/tags/__init__.py b/novem/tags/__init__.py
index cfcf4f8..53a6744 100644
--- a/novem/tags/__init__.py
+++ b/novem/tags/__init__.py
@@ -17,10 +17,11 @@ def is_valid_tag(tag: str) -> bool:
     Valid tags are:
     - One of: fav, like, ignore, wip, archived
     - Any string starting with + (user tag)
+    - Any string starting with = (category tag)
     """
     if not tag:
         return False
-    return tag in VALID_TAGS or tag.startswith("+")
+    return tag in VALID_TAGS or tag.startswith("+") or tag.startswith("=")
 
 
 class NovemTags:
@@ -30,7 +31,7 @@ class NovemTags:
     Novem tags are exposed at:
       f"{api._api_root}{tag_path}/tags"
 
-    Valid tags are: fav, like, ignore, wip, archived, or any tag starting with + (user tag)
+    Valid tags are: fav, like, ignore, wip, archived, +usertag, or =categorytag
     """
 
     def __init__(self, api: "NovemAPI", tag_path: str) -> None: