diff --git a/src/pytorch_ie/core/metric.py b/src/pytorch_ie/core/metric.py
index d7046202..54febd85 100644
--- a/src/pytorch_ie/core/metric.py
+++ b/src/pytorch_ie/core/metric.py
@@ -1,28 +1,19 @@
 from abc import ABC, abstractmethod
-from typing import Dict, Generic, Iterable, Optional, Type, TypeVar, Union
+from typing import Dict, Generic, Iterable, Optional, TypeVar, Union
 
 from pytorch_ie.core.document import Document
+from pytorch_ie.core.module_mixins import RequiresDocumentTypeMixin
 
 T = TypeVar("T")
 
 
-class DocumentMetric(ABC, Generic[T]):
+class DocumentMetric(ABC, RequiresDocumentTypeMixin, Generic[T]):
     """This defines the interface for a document metric."""
 
-    # The document type that this metric can process. Will be used for auto-conversion, if available.
-    # Overwrite this if the metric requires a specific document type, e.g. a TextBasedDocument.
-    DOCUMENT_TYPE: Optional[Type[Document]] = None
-
     def __init__(self):
         self.reset()
         self._current_split: Optional[str] = None
 
-    @property
-    def document_type(self) -> Optional[Type[Document]]:
-        """The document type that this metric can process. Will be used for auto-conversion, if available.
-        Overwrite this if the document type depends on some parameters of the metric."""
-        return self.DOCUMENT_TYPE
-
     @abstractmethod
     def reset(self) -> None:
         """Any reset logic that needs to be performed before the metric is called again."""
diff --git a/src/pytorch_ie/core/taskmodule.py b/src/pytorch_ie/core/taskmodule.py
index 3f055352..e137ef5e 100644
--- a/src/pytorch_ie/core/taskmodule.py
+++ b/src/pytorch_ie/core/taskmodule.py
@@ -12,7 +12,6 @@
     Optional,
     Sequence,
     Tuple,
-    Type,
     TypeVar,
     Union,
     overload,
@@ -24,6 +23,7 @@
 
 from pytorch_ie.core.document import Annotation, Document
 from pytorch_ie.core.hf_hub_mixin import PieTaskModuleHFHubMixin
+from pytorch_ie.core.module_mixins import RequiresDocumentTypeMixin
 from pytorch_ie.core.registrable import Registrable
 from pytorch_ie.data import Dataset, IterableDataset
 
@@ -149,6 +149,7 @@ class TaskModule(
     PieTaskModuleHFHubMixin,
     HyperparametersMixin,
     Registrable,
+    RequiresDocumentTypeMixin,
     Generic[
         DocumentType,
         InputEncoding,
@@ -159,16 +160,11 @@ class TaskModule(
     ],
 ):
     PREPARED_ATTRIBUTES: List[str] = []
-    DOCUMENT_TYPE: Optional[Type[DocumentType]] = None
 
     def __init__(self, encode_document_batch_size: Optional[int] = None, **kwargs):
         super().__init__(**kwargs)
         self.encode_document_batch_size = encode_document_batch_size
 
-    @property
-    def document_type(self) -> Optional[Type[DocumentType]]:
-        return self.DOCUMENT_TYPE
-
     @property
     def is_prepared(self):
         """