diff --git a/end_to_end_tests/golden-record/my_test_api_client/models/body_upload_file_tests_upload_post.py b/end_to_end_tests/golden-record/my_test_api_client/models/body_upload_file_tests_upload_post.py
index 85bd57118..4863298fc 100644
--- a/end_to_end_tests/golden-record/my_test_api_client/models/body_upload_file_tests_upload_post.py
+++ b/end_to_end_tests/golden-record/my_test_api_client/models/body_upload_file_tests_upload_post.py
@@ -1,8 +1,10 @@
+import datetime
 import json
 from io import BytesIO
 from typing import Any, Dict, List, Optional, Tuple, Type, TypeVar, Union, cast
 
 import attr
+from dateutil.parser import isoparse
 
 from ..models.body_upload_file_tests_upload_post_additional_property import (
     BodyUploadFileTestsUploadPostAdditionalProperty,
@@ -28,6 +30,8 @@ class BodyUploadFileTestsUploadPost:
         some_object (BodyUploadFileTestsUploadPostSomeObject):
         some_optional_file (Union[Unset, File]):
         some_string (Union[Unset, str]):  Default: 'some_default_string'.
+        a_datetime (Union[Unset, datetime.datetime]):
+        a_date (Union[Unset, datetime.date]):
         some_number (Union[Unset, float]):
         some_array (Union[Unset, List[float]]):
         some_optional_object (Union[Unset, BodyUploadFileTestsUploadPostSomeOptionalObject]):
@@ -40,6 +44,8 @@ class BodyUploadFileTestsUploadPost:
     some_nullable_object: Optional[BodyUploadFileTestsUploadPostSomeNullableObject]
     some_optional_file: Union[Unset, File] = UNSET
     some_string: Union[Unset, str] = "some_default_string"
+    a_datetime: Union[Unset, datetime.datetime] = UNSET
+    a_date: Union[Unset, datetime.date] = UNSET
     some_number: Union[Unset, float] = UNSET
     some_array: Union[Unset, List[float]] = UNSET
     some_optional_object: Union[Unset, BodyUploadFileTestsUploadPostSomeOptionalObject] = UNSET
@@ -58,6 +64,14 @@ def to_dict(self) -> Dict[str, Any]:
             some_optional_file = self.some_optional_file.to_tuple()
 
         some_string = self.some_string
+        a_datetime: Union[Unset, str] = UNSET
+        if not isinstance(self.a_datetime, Unset):
+            a_datetime = self.a_datetime.isoformat()
+
+        a_date: Union[Unset, str] = UNSET
+        if not isinstance(self.a_date, Unset):
+            a_date = self.a_date.isoformat()
+
         some_number = self.some_number
         some_array: Union[Unset, List[float]] = UNSET
         if not isinstance(self.some_array, Unset):
@@ -88,6 +102,10 @@ def to_dict(self) -> Dict[str, Any]:
             field_dict["some_optional_file"] = some_optional_file
         if some_string is not UNSET:
             field_dict["some_string"] = some_string
+        if a_datetime is not UNSET:
+            field_dict["a_datetime"] = a_datetime
+        if a_date is not UNSET:
+            field_dict["a_date"] = a_date
         if some_number is not UNSET:
             field_dict["some_number"] = some_number
         if some_array is not UNSET:
@@ -113,6 +131,14 @@ def to_multipart(self) -> Dict[str, Any]:
             if isinstance(self.some_string, Unset)
             else (None, str(self.some_string).encode(), "text/plain")
         )
+        a_datetime: Union[Unset, bytes] = UNSET
+        if not isinstance(self.a_datetime, Unset):
+            a_datetime = self.a_datetime.isoformat().encode()
+
+        a_date: Union[Unset, bytes] = UNSET
+        if not isinstance(self.a_date, Unset):
+            a_date = self.a_date.isoformat().encode()
+
         some_number = (
             self.some_number
             if isinstance(self.some_number, Unset)
@@ -152,6 +178,10 @@ def to_multipart(self) -> Dict[str, Any]:
             field_dict["some_optional_file"] = some_optional_file
         if some_string is not UNSET:
             field_dict["some_string"] = some_string
+        if a_datetime is not UNSET:
+            field_dict["a_datetime"] = a_datetime
+        if a_date is not UNSET:
+            field_dict["a_date"] = a_date
         if some_number is not UNSET:
             field_dict["some_number"] = some_number
         if some_array is not UNSET:
@@ -179,6 +209,20 @@ def from_dict(cls: Type[T], src_dict: Dict[str, Any]) -> T:
 
         some_string = d.pop("some_string", UNSET)
 
+        _a_datetime = d.pop("a_datetime", UNSET)
+        a_datetime: Union[Unset, datetime.datetime]
+        if isinstance(_a_datetime, Unset):
+            a_datetime = UNSET
+        else:
+            a_datetime = isoparse(_a_datetime)
+
+        _a_date = d.pop("a_date", UNSET)
+        a_date: Union[Unset, datetime.date]
+        if isinstance(_a_date, Unset):
+            a_date = UNSET
+        else:
+            a_date = isoparse(_a_date).date()
+
         some_number = d.pop("some_number", UNSET)
 
         some_array = cast(List[float], d.pop("some_array", UNSET))
@@ -209,6 +253,8 @@ def from_dict(cls: Type[T], src_dict: Dict[str, Any]) -> T:
             some_object=some_object,
             some_optional_file=some_optional_file,
             some_string=some_string,
+            a_datetime=a_datetime,
+            a_date=a_date,
             some_number=some_number,
             some_array=some_array,
             some_optional_object=some_optional_object,
diff --git a/end_to_end_tests/openapi.json b/end_to_end_tests/openapi.json
index 22e095511..b958e530b 100644
--- a/end_to_end_tests/openapi.json
+++ b/end_to_end_tests/openapi.json
@@ -1309,6 +1309,16 @@
             "type": "string",
             "default": "some_default_string"
           },
+          "a_datetime": {
+            "title": "A Datetime",
+            "type": "string",
+            "format": "date-time"
+          },
+          "a_date": {
+            "title": "A Date",
+            "type": "string",
+            "format": "date"
+          },
           "some_number": {
             "title": "Some Number",
             "type": "number"
diff --git a/openapi_python_client/templates/property_templates/date_property.py.jinja b/openapi_python_client/templates/property_templates/date_property.py.jinja
index f0dd00ba9..2107c5cb5 100644
--- a/openapi_python_client/templates/property_templates/date_property.py.jinja
+++ b/openapi_python_client/templates/property_templates/date_property.py.jinja
@@ -18,7 +18,13 @@ isoparse({{ source }}).date()
 {% if property.required %}
 {{ destination }} = {{ transformed }} {% if property.nullable %}if {{ source }} else None {%endif%}
 {% else %}
-{{ destination }}{% if declare_type %}: {{ property.get_type_string(json=True) }}{% endif %} = UNSET
+{% if declare_type %}
+{% set type_annotation = property.get_type_string(json=True) %}
+{% if multipart %}{% set type_annotation = type_annotation | replace("str", "bytes") %}{% endif %}
+{{ destination }}: {{ type_annotation }} = UNSET
+{% else %}
+{{ destination }} = UNSET
+{% endif %}
 if not isinstance({{ source }}, Unset):
 {% if property.nullable %}
     {{ destination }} = {{ transformed }} if {{ source }} else None
diff --git a/openapi_python_client/templates/property_templates/datetime_property.py.jinja b/openapi_python_client/templates/property_templates/datetime_property.py.jinja
index 6653a6134..29a2b417d 100644
--- a/openapi_python_client/templates/property_templates/datetime_property.py.jinja
+++ b/openapi_python_client/templates/property_templates/datetime_property.py.jinja
@@ -22,7 +22,13 @@ isoparse({{ source }})
 {{ destination }} = {{ transformed }}
 {% endif %}
 {% else %}
-{{ destination }}{% if declare_type %}: {{ property.get_type_string(json=True) }}{% endif %} = UNSET
+{% if declare_type %}
+{% set type_annotation = property.get_type_string(json=True) %}
+{% if multipart %}{% set type_annotation = type_annotation | replace("str", "bytes") %}{% endif %}
+{{ destination }}: {{ type_annotation }} = UNSET
+{% else %}
+{{ destination }} = UNSET
+{% endif %}
 if not isinstance({{ source }}, Unset):
 {% if property.nullable %}
     {{ destination }} = {{ transformed }} if {{ source }} else None