diff --git a/CHANGELOG.md b/CHANGELOG.md
index 16f27086b..17db7b366 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -28,6 +28,9 @@
   - [v0.3.0](services/cost/CHANGELOG.md#v030)
     - **Chore:** Bump minimum Python version to 3.10
     - **Chore:** Update dependencies
+  - [v0.4.0](services/cost/CHANGELOG.md#v040)
+    - **Feature:** Add attribute `total_quantity_decimal` to `DetailedServiceCost` model class
+    - **Feature:** Add attribute `quantity_decimal` to `ReportData` model class
 - `dns`
   - [v0.7.0](services/dns/CHANGELOG.md#v070)
     - **Chore:** Bump minimum Python version to 3.10
diff --git a/services/cost/CHANGELOG.md b/services/cost/CHANGELOG.md
index ed40ae2e0..689a708ca 100644
--- a/services/cost/CHANGELOG.md
+++ b/services/cost/CHANGELOG.md
@@ -1,3 +1,7 @@
+## v0.4.0
+- **Feature:** Add attribute `total_quantity_decimal` to `DetailedServiceCost` model class
+- **Feature:** Add attribute `quantity_decimal` to `ReportData` model class
+
 ## v0.3.0
 - **Chore:** Bump minimum Python version to 3.10
 - **Chore:** Update dependencies
diff --git a/services/cost/oas_commit b/services/cost/oas_commit
index c08a6770d..b687a3969 100644
--- a/services/cost/oas_commit
+++ b/services/cost/oas_commit
@@ -1 +1 @@
-4407196dbbef4e53e6798809e856725cbc84ae05
+f22dd14374388602d895c8892b3e5b110dc16582
diff --git a/services/cost/pyproject.toml b/services/cost/pyproject.toml
index 6a0b54c9d..efe6c5bbf 100644
--- a/services/cost/pyproject.toml
+++ b/services/cost/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "stackit-cost"
-version = "v0.3.0"
+version = "v0.4.0"
 description = "STACKIT Cost API"
 authors = [{name = "STACKIT Developer Tools", email = "developer-tools@stackit.cloud"}]
 requires-python = ">=3.10,<4.0"
diff --git a/services/cost/src/stackit/cost/models/detailed_service_cost.py b/services/cost/src/stackit/cost/models/detailed_service_cost.py
index 5bdc5c8a3..a79e3ab00 100644
--- a/services/cost/src/stackit/cost/models/detailed_service_cost.py
+++ b/services/cost/src/stackit/cost/models/detailed_service_cost.py
@@ -23,6 +23,7 @@
     Field,
     StrictFloat,
     StrictInt,
+    StrictStr,
 )
 from pydantic_core import to_jsonable_python
 from typing_extensions import Annotated, Self
@@ -56,6 +57,10 @@ class DetailedServiceCost(BaseModel):
         alias="totalDiscount",
     )
     total_quantity: StrictInt = Field(description="Total quantity", alias="totalQuantity")
+    total_quantity_decimal: StrictStr = Field(
+        description="Total quantity in decimal format, returned as string to preserve precision. NOTE: This field will be removed in future versions and `totalQuantity` will become a decimal. ",
+        alias="totalQuantityDecimal",
+    )
     unit_label: Annotated[str, Field(min_length=1, strict=True, max_length=64)] = Field(
         description="Label for unit", alias="unitLabel"
     )
@@ -67,6 +72,7 @@ class DetailedServiceCost(BaseModel):
         "totalCharge",
         "totalDiscount",
         "totalQuantity",
+        "totalQuantityDecimal",
         "unitLabel",
     ]
 
@@ -138,6 +144,7 @@ def from_dict(cls, obj: Optional[Dict[str, Any]]) -> Optional[Self]:
                 "totalCharge": obj.get("totalCharge"),
                 "totalDiscount": obj.get("totalDiscount"),
                 "totalQuantity": obj.get("totalQuantity"),
+                "totalQuantityDecimal": obj.get("totalQuantityDecimal"),
                 "unitLabel": obj.get("unitLabel"),
             }
         )
diff --git a/services/cost/src/stackit/cost/models/report_data.py b/services/cost/src/stackit/cost/models/report_data.py
index 309f2fa93..85cfa2519 100644
--- a/services/cost/src/stackit/cost/models/report_data.py
+++ b/services/cost/src/stackit/cost/models/report_data.py
@@ -23,6 +23,7 @@
     Field,
     StrictFloat,
     StrictInt,
+    StrictStr,
 )
 from pydantic_core import to_jsonable_python
 from typing_extensions import Self
@@ -38,8 +39,12 @@ class ReportData(BaseModel):
     charge: Union[StrictFloat, StrictInt] = Field(description="Charge, value in cents")
     discount: Union[StrictFloat, StrictInt] = Field(description="Discount, value in cents")
     quantity: StrictInt = Field(description="Quantity")
+    quantity_decimal: StrictStr = Field(
+        description="Quantity in decimal format, returned as string to preserve precision. NOTE: This field will be removed in future versions and `totalQuantity` will become a decimal. ",
+        alias="quantityDecimal",
+    )
     time_period: ReportDataTimePeriod = Field(alias="timePeriod")
-    __properties: ClassVar[List[str]] = ["charge", "discount", "quantity", "timePeriod"]
+    __properties: ClassVar[List[str]] = ["charge", "discount", "quantity", "quantityDecimal", "timePeriod"]
 
     model_config = ConfigDict(
         validate_by_name=True,
@@ -97,6 +102,7 @@ def from_dict(cls, obj: Optional[Dict[str, Any]]) -> Optional[Self]:
                 "charge": obj.get("charge"),
                 "discount": obj.get("discount"),
                 "quantity": obj.get("quantity"),
+                "quantityDecimal": obj.get("quantityDecimal"),
                 "timePeriod": (
                     ReportDataTimePeriod.from_dict(obj["timePeriod"]) if obj.get("timePeriod") is not None else None
                 ),