diff --git a/Makefile b/Makefile
index ac4e9a5..f5b272b 100644
--- a/Makefile
+++ b/Makefile
@@ -17,7 +17,7 @@ pylint:
 	poetry run pylint chili
 
 mypy:
-	poetry run mypy --install-types --non-interactive .
+	poetry run mypy --install-types --non-interactive chili
 
 bandit:
 	poetry run bandit -r . -x ./tests,./test,./.venv
diff --git a/chili/decoder.py b/chili/decoder.py
index 056eb0b..207009f 100644
--- a/chili/decoder.py
+++ b/chili/decoder.py
@@ -40,6 +40,7 @@
     UNDEFINED,
     TypeSchema,
     create_schema,
+    get_non_optional_fields,
     get_origin_type,
     get_parameters_map,
     get_type_args,
@@ -286,7 +287,7 @@ class UnionDecoder(TypeDecoder):
     }
     _CASTABLES_TYPES = {decimal.Decimal}
 
-    def __init__(self, valid_types: List[Type]):
+    def __init__(self, valid_types: List[Type], extra_decoders: TypeDecoders = None, force: bool = False):
         self.valid_types = valid_types
         self._type_decoders = {}
 
@@ -294,7 +295,11 @@ def __init__(self, valid_types: List[Type]):
             if a_type in self._PRIMITIVE_TYPES:
                 self._type_decoders[a_type] = a_type
                 continue
-            self._type_decoders[a_type] = build_type_decoder(a_type)  # type: ignore
+            self._type_decoders[a_type] = build_type_decoder(
+                a_type, extra_decoders=extra_decoders, force=force  # type: ignore
+            )
+
+        self.force = force
 
     def decode(self, value: Any) -> Any:
         passed_type = type(value)
@@ -317,13 +322,15 @@ def decode(self, value: Any) -> Any:
                     continue
 
         if passed_type is dict:
-            value_keys = value.keys()
-            for decodable, decoder in self._type_decoders.items():
+            provided_fields = set(value.keys())
+            for class_name, decoder in self._type_decoders.items():
                 try:
-                    if not is_decodable(decodable) and value_keys == get_type_hints(decodable).keys():
-                        return decoder.decode(value)
-                    if is_decodable(decodable) and value_keys == getattr(decodable, _PROPERTIES, {}).keys():
-                        return decoder.decode(value)
+                    if is_decodable(class_name) or is_dataclass(class_name) or self.force:
+                        expected_fields = set(get_non_optional_fields(class_name))
+                        if provided_fields.issubset(expected_fields):
+                            return decoder.decode(value)
+                        continue
+                    continue
                 except Exception:
                     continue
 
@@ -497,7 +504,7 @@ def build_type_decoder(
             return OptionalTypeDecoder(
                 build_type_decoder(a_type=type_args[0], extra_decoders=extra_decoders)  # type: ignore
             )
-        return UnionDecoder(type_args)
+        return UnionDecoder(type_args, extra_decoders=extra_decoders, force=force)
 
     if isinstance(a_type, typing.ForwardRef) and module is not None:
         resolved_reference = resolve_forward_reference(module, a_type)
diff --git a/chili/encoder.py b/chili/encoder.py
index f730730..ecd3b4e 100644
--- a/chili/encoder.py
+++ b/chili/encoder.py
@@ -40,7 +40,6 @@
     unpack_optional,
 )
 
-
 if sys.version_info >= (3, 10):
     from types import UnionType
 else:
@@ -341,16 +340,17 @@ def encode(self, value: Any) -> Any:
 
 
 class UnionEncoder(TypeEncoder):
-    def __init__(self, supported_types: List[Type], extra_encoders: TypeEncoders = None):
+    def __init__(self, supported_types: List[Type], extra_encoders: TypeEncoders = None, force: bool = False):
         self.supported_types = supported_types
         self._extra_encoders = extra_encoders
+        self.force = force
 
     def encode(self, value: Any) -> Any:
         value_type = type(value)
         if value_type not in self.supported_types:
             raise EncoderError.invalid_input
 
-        return build_type_encoder(value_type, self._extra_encoders).encode(value)  # type: ignore
+        return build_type_encoder(value_type, self._extra_encoders, force=self.force).encode(value)  # type: ignore
 
 
 _supported_generics = {
@@ -405,7 +405,7 @@ def build_type_encoder(
         type_args = get_type_args(a_type)
         if len(type_args) == 2 and type_args[-1] is type(None):
             return OptionalTypeEncoder(build_type_encoder(type_args[0], extra_encoders))  # type: ignore
-        return UnionEncoder(type_args, extra_encoders)
+        return UnionEncoder(type_args, extra_encoders, force=force)
 
     if isinstance(a_type, typing.ForwardRef) and module is not None:
         resolved_reference = resolve_forward_reference(module, a_type)
diff --git a/chili/typing.py b/chili/typing.py
index d489038..a4505fc 100644
--- a/chili/typing.py
+++ b/chili/typing.py
@@ -7,7 +7,7 @@
 from enum import Enum
 from functools import lru_cache
 from inspect import isclass as is_class
-from typing import Any, Callable, ClassVar, Dict, List, NewType, Optional, Type, Union
+from typing import Any, Callable, ClassVar, Dict, List, NewType, Optional, Type, Union, get_type_hints
 
 from chili.error import SerialisationError
 
@@ -27,6 +27,7 @@
     "get_origin_type",
     "get_parameters_map",
     "get_type_args",
+    "get_type_hints",
     "get_type_parameters",
     "is_class",
     "is_dataclass",
@@ -43,6 +44,15 @@
 ]
 
 
+def get_non_optional_fields(type_name: Type) -> List[str]:
+    if is_encodable(type_name):
+        schema = getattr(type_name, _ENCODABLE)
+    else:
+        schema = create_schema(type_name)  # type: ignore
+
+    return [field.name for field in schema.values() if not is_optional(field.type)]
+
+
 def get_origin_type(type_name: Type) -> Optional[Type]:
     return getattr(type_name, "__origin__", None)
 
diff --git a/pyproject.toml b/pyproject.toml
index 70ca4b1..16aef60 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -22,7 +22,7 @@ license = "MIT"
 name = "chili"
 readme = "README.md"
 repository = "https://github.com/kodemore/chili"
-version = "2.8.0"
+version = "2.8.1"
 
 [tool.poetry.dependencies]
 gaffe = ">=0.3.0"
diff --git a/tests/test_typing.py b/tests/test_typing.py
new file mode 100644
index 0000000..0a97995
--- /dev/null
+++ b/tests/test_typing.py
@@ -0,0 +1,34 @@
+from dataclasses import dataclass
+from typing import Optional
+
+from chili.typing import get_non_optional_fields
+
+
+def test_get_non_optional_fields_from_data_class() -> None:
+    # given
+    @dataclass
+    class Person:
+        name: str
+        age: int
+        street_name: Optional[str]
+        street_number: Optional[int]
+
+    # when
+    fields = get_non_optional_fields(Person)
+
+    # then
+    assert fields == ["name", "age"]
+
+
+def test_get_non_optional_fields_from_class() -> None:
+    class Person:
+        name: str
+        age: int
+        street_name: Optional[str]
+        street_number: Optional[int]
+
+    # when
+    fields = get_non_optional_fields(Person)
+
+    # then
+    assert fields == ["name", "age"]
diff --git a/tests/usecases/newtype_test.py b/tests/usecases/newtype_test.py
index 8b437e9..2fd10b6 100644
--- a/tests/usecases/newtype_test.py
+++ b/tests/usecases/newtype_test.py
@@ -1,6 +1,7 @@
+import sys
 from typing import NewType
+
 from chili import Decoder, Encoder, decodable, encodable
-import sys
 
 
 def test_can_encode_newtype_type() -> None:
diff --git a/tests/usecases/union_usecase.py b/tests/usecases/union_usecase.py
index 6f711e0..5f10924 100644
--- a/tests/usecases/union_usecase.py
+++ b/tests/usecases/union_usecase.py
@@ -1,5 +1,5 @@
 from dataclasses import dataclass
-from typing import List, Union
+from typing import List, Optional, Union
 
 from chili import decode, encode
 
@@ -88,3 +88,48 @@ class EmailAddress:
 
     # then
     assert result == {"address": "simple@email.com", "label": ""}
+
+
+def test_can_decode_nested_union() -> None:
+    # given
+    @dataclass
+    class HomeAddress:
+        home_street: str
+        number: Optional[int] = 0
+
+    @dataclass
+    class OfficeAddress:
+        office_street: str
+        number: Optional[int] = 0
+
+    @dataclass
+    class Address:
+        street: str
+        number: Optional[int] = 0
+
+    @dataclass
+    class Person:
+        name: str
+        address: HomeAddress | OfficeAddress | Address
+
+    data_office = {
+        "name": "Bob",
+        "address": {"office_street": "street"},
+    }
+
+    data_home = {
+        "name": "Bob",
+        "address": {"home_street": "home"},
+    }
+
+    # when
+    decoded = decode(data_office, Person)
+
+    # then
+    assert isinstance(decoded.address, OfficeAddress)
+
+    # when
+    decoded = decode(data_home, Person)
+
+    # then
+    assert isinstance(decoded.address, HomeAddress)