diff --git a/dev/generate_filter.py b/dev/generate_filter.py
index 0188187..19f4f73 100644
--- a/dev/generate_filter.py
+++ b/dev/generate_filter.py
@@ -1,6 +1,7 @@
 """
 Helper script to automatically generate pydantic models from a swagger spec
 """
+
 import json
 import sys
 from pathlib import Path
diff --git a/easyverein/api.py b/easyverein/api.py
index 266f7af..06e500a 100644
--- a/easyverein/api.py
+++ b/easyverein/api.py
@@ -1,6 +1,7 @@
 """
 Main EasyVerein API class
 """
+
 import logging
 
 from .core.client import EasyvereinClient
diff --git a/easyverein/core/client.py b/easyverein/core/client.py
index 86b6869..2845c81 100644
--- a/easyverein/core/client.py
+++ b/easyverein/core/client.py
@@ -1,6 +1,7 @@
 """
 Main EasyVerein API class
 """
+
 from __future__ import annotations
 
 import logging
diff --git a/easyverein/core/protocol.py b/easyverein/core/protocol.py
index c3fb4bf..39a42b3 100644
--- a/easyverein/core/protocol.py
+++ b/easyverein/core/protocol.py
@@ -9,21 +9,16 @@
 # noinspection PyPropertyDefinition
 class IsEVClientProtocol(Protocol):
     @property
-    def logger(self) -> logging.Logger:
-        ...
+    def logger(self) -> logging.Logger: ...
 
     @property
-    def c(self) -> EasyvereinClient:
-        ...
+    def c(self) -> EasyvereinClient: ...
 
     @property
-    def endpoint_name(self) -> str:
-        ...
+    def endpoint_name(self) -> str: ...
 
     @property
-    def model_class(self) -> TypeVar:
-        ...
+    def model_class(self) -> TypeVar: ...
 
     @property
-    def return_type(self) -> Type[BaseModel]:
-        ...
+    def return_type(self) -> Type[BaseModel]: ...
diff --git a/easyverein/core/types.py b/easyverein/core/types.py
index 5c0d6dc..f5adafb 100644
--- a/easyverein/core/types.py
+++ b/easyverein/core/types.py
@@ -1,6 +1,7 @@
 """
 Custom types used for model validation
 """
+
 import datetime
 import json
 from typing import Annotated
diff --git a/easyverein/models/contact_details.py b/easyverein/models/contact_details.py
index ab594be..739f1f4 100644
--- a/easyverein/models/contact_details.py
+++ b/easyverein/models/contact_details.py
@@ -1,6 +1,7 @@
 """
 Contact Details related models
 """
+
 from __future__ import annotations
 
 from typing import Any, Literal
diff --git a/easyverein/models/custom_field.py b/easyverein/models/custom_field.py
index ca99e8b..5500fab 100644
--- a/easyverein/models/custom_field.py
+++ b/easyverein/models/custom_field.py
@@ -1,6 +1,7 @@
 """
 Member related models
 """
+
 from __future__ import annotations
 
 from typing import Literal
@@ -36,9 +37,9 @@ class CustomFieldBase(EasyVereinBase):
     color: HexColor = None
     short: str | None = Field(default=None, max_length=4)
     orderSequence: PositiveIntWithZero | None = None
-    settings_type: Literal[
-        "t", "f", "z", "d", "c", "r", "s", "a", "b", "m"
-    ] | None = None
+    settings_type: Literal["t", "f", "z", "d", "c", "r", "s", "a", "b", "m"] | None = (
+        None
+    )
     """
     Settings type defines which type of field this custom field should be. Possible values:
 
@@ -55,9 +56,12 @@ class CustomFieldBase(EasyVereinBase):
 
     If type is set to s or a, the possible options need to be defined in the additional field
     """
-    kind: Literal[
-        "a", "b", "ba", "ca", "iv", "t", "u", "ic", "c", "e", "h", "j", "i", "k"
-    ] | None = None
+    kind: (
+        Literal[
+            "a", "b", "ba", "ca", "iv", "t", "u", "ic", "c", "e", "h", "j", "i", "k"
+        ]
+        | None
+    ) = None
     """
     Kind defines in which context this custom field is used. Unfortunately only some possible values are
     documented in the API spec:
diff --git a/easyverein/models/invoice.py b/easyverein/models/invoice.py
index 1a5f640..73c1afb 100644
--- a/easyverein/models/invoice.py
+++ b/easyverein/models/invoice.py
@@ -1,6 +1,7 @@
 """
 Invoice related models
 """
+
 from __future__ import annotations
 
 from typing import Literal
@@ -42,9 +43,18 @@ class InvoiceBase(EasyVereinBase):
     taxName: str | None = None
     relatedAddress: ContactDetails | EasyVereinReference | None = None
     path: EasyVereinReference | None = None
-    kind: Literal[
-        "balance", "donation", "membership", "revenue", "expense", "cancel", "credit"
-    ] | None = None
+    kind: (
+        Literal[
+            "balance",
+            "donation",
+            "membership",
+            "revenue",
+            "expense",
+            "cancel",
+            "credit",
+        ]
+        | None
+    ) = None
     # TODO: Add reference to BillingAccount once implemented
     selectionAcc: EasyVereinReference | None = None
     refNumber: str | None = None
diff --git a/easyverein/models/invoice_item.py b/easyverein/models/invoice_item.py
index 61caa39..84b5b97 100644
--- a/easyverein/models/invoice_item.py
+++ b/easyverein/models/invoice_item.py
@@ -1,6 +1,7 @@
 """
 Invoice Item model
 """
+
 from __future__ import annotations
 
 from typing import Annotated
diff --git a/easyverein/models/member.py b/easyverein/models/member.py
index 4e640ba..585f84d 100644
--- a/easyverein/models/member.py
+++ b/easyverein/models/member.py
@@ -1,6 +1,7 @@
 """
 Member related models
 """
+
 from __future__ import annotations
 
 from typing import Literal
diff --git a/easyverein/models/mixins/empty_strings_mixin.py b/easyverein/models/mixins/empty_strings_mixin.py
index c4a46c9..dfb49bf 100644
--- a/easyverein/models/mixins/empty_strings_mixin.py
+++ b/easyverein/models/mixins/empty_strings_mixin.py
@@ -2,6 +2,7 @@
 This module contains a generic plugin for Pydantic models that removes
 empty strings and converts them to None.
 """
+
 from typing import Any
 
 from pydantic import model_validator
diff --git a/easyverein/models/mixins/required_attributes.py b/easyverein/models/mixins/required_attributes.py
index fb8d99b..a77e86c 100644
--- a/easyverein/models/mixins/required_attributes.py
+++ b/easyverein/models/mixins/required_attributes.py
@@ -1,6 +1,7 @@
 """
 This module contains a class factory returning a Mixin class
 """
+
 from typing import Self
 
 from pydantic import BaseModel, model_validator
diff --git a/easyverein/modules/contact_details.py b/easyverein/modules/contact_details.py
index ebaa30b..98eb2ea 100644
--- a/easyverein/modules/contact_details.py
+++ b/easyverein/modules/contact_details.py
@@ -1,6 +1,7 @@
 """
 All methods related to contact details
 """
+
 import logging
 
 from ..core.client import EasyvereinClient
diff --git a/easyverein/modules/custom_field.py b/easyverein/modules/custom_field.py
index 65f95ec..fffafce 100644
--- a/easyverein/modules/custom_field.py
+++ b/easyverein/modules/custom_field.py
@@ -1,6 +1,7 @@
 """
 All methods related to custom fields
 """
+
 import logging
 
 from ..core.client import EasyvereinClient
diff --git a/easyverein/modules/invoice_item.py b/easyverein/modules/invoice_item.py
index 5aade84..5eecd30 100644
--- a/easyverein/modules/invoice_item.py
+++ b/easyverein/modules/invoice_item.py
@@ -1,6 +1,7 @@
 """
 All methods related to invoices
 """
+
 import logging
 
 from ..core.client import EasyvereinClient
diff --git a/easyverein/modules/member.py b/easyverein/modules/member.py
index 6104250..8d8f6e8 100644
--- a/easyverein/modules/member.py
+++ b/easyverein/modules/member.py
@@ -1,6 +1,7 @@
 """
 All methods related to invoices
 """
+
 import logging
 
 from ..core.client import EasyvereinClient
diff --git a/easyverein/modules/member_custom_field.py b/easyverein/modules/member_custom_field.py
index 3ea6f40..d48da90 100644
--- a/easyverein/modules/member_custom_field.py
+++ b/easyverein/modules/member_custom_field.py
@@ -1,6 +1,7 @@
 """
 All methods related to invoices
 """
+
 import logging
 
 from ..core.client import EasyvereinClient