diff --git a/aleph_message/models/__init__.py b/aleph_message/models/__init__.py
index 8dcfb29..8afec37 100644
--- a/aleph_message/models/__init__.py
+++ b/aleph_message/models/__init__.py
@@ -215,9 +215,6 @@ class BaseMessage(BaseModel):
     )
     item_hash: ItemHash = Field(description="Hash of the content (sha256 by default)")
     content: BaseContent = Field(description="Content of the message, ready to be used")
-    tags: Optional[List[str]] = Field(
-        default=None, description="Tags associated with the message"
-    )
 
     forgotten_by: Optional[List[str]]
 
diff --git a/aleph_message/models/abstract.py b/aleph_message/models/abstract.py
index f272dbd..0a66dc7 100644
--- a/aleph_message/models/abstract.py
+++ b/aleph_message/models/abstract.py
@@ -1,4 +1,6 @@
-from pydantic import BaseModel, Extra
+from typing import List, Optional
+
+from pydantic import BaseModel, Extra, Field
 
 
 def hashable(obj):
@@ -23,6 +25,9 @@ class BaseContent(BaseModel):
 
     address: str
     time: float
+    tags: Optional[List[str]] = Field(
+        default=None, description="Tags associated with the message"
+    )
 
     class Config:
         extra = Extra.forbid