diff --git a/changelog_entry.yaml b/changelog_entry.yaml
index e69de29b..039c5fd3 100644
--- a/changelog_entry.yaml
+++ b/changelog_entry.yaml
@@ -0,0 +1,4 @@
+- bump: patch
+  changes:
+    added:
+    - Output storage for household simulation calculations in simulations table
diff --git a/policyengine_api/data/initialise.sql b/policyengine_api/data/initialise.sql
index 117045cf..01cd0d7d 100644
--- a/policyengine_api/data/initialise.sql
+++ b/policyengine_api/data/initialise.sql
@@ -111,7 +111,10 @@ CREATE TABLE IF NOT EXISTS simulations (
     -- VARCHAR(255) to accommodate both household IDs and geography codes
     population_id VARCHAR(255) NOT NULL,
     population_type VARCHAR(50) NOT NULL,
-    policy_id INT NOT NULL
+    policy_id INT NOT NULL,
+    -- output_json stores calculation results for household simulations only
+    -- For geography simulations, outputs are stored in report_outputs table
+    output_json JSON DEFAULT NULL
 );
 
 CREATE TABLE IF NOT EXISTS report_outputs (
diff --git a/policyengine_api/data/initialise_local.sql b/policyengine_api/data/initialise_local.sql
index 13bc68ff..42f78c35 100644
--- a/policyengine_api/data/initialise_local.sql
+++ b/policyengine_api/data/initialise_local.sql
@@ -120,7 +120,10 @@ CREATE TABLE IF NOT EXISTS simulations (
     -- VARCHAR(255) to accommodate both household IDs and geography codes
     population_id VARCHAR(255) NOT NULL,
     population_type VARCHAR(50) NOT NULL,
-    policy_id INT NOT NULL
+    policy_id INT NOT NULL,
+    -- output_json stores calculation results for household simulations only
+    -- For geography simulations, outputs are stored in report_outputs table
+    output_json JSON DEFAULT NULL
 );
 
 CREATE TABLE IF NOT EXISTS report_outputs (
diff --git a/policyengine_api/routes/simulation_routes.py b/policyengine_api/routes/simulation_routes.py
index 6669ef89..986a97b1 100644
--- a/policyengine_api/routes/simulation_routes.py
+++ b/policyengine_api/routes/simulation_routes.py
@@ -133,3 +133,78 @@ def get_simulation(country_id: str, simulation_id: int) -> Response:
         status=200,
         mimetype="application/json",
     )
+
+
+@simulation_bp.route("/<country_id>/simulation", methods=["PATCH"])
+@validate_country
+def update_simulation(country_id: str) -> Response:
+    """
+    Update a simulation record with calculation output.
+
+    Args:
+        country_id (str): The country ID.
+
+    Request body can contain:
+        - id (int): The simulation ID.
+        - output_json (str): The calculation output as JSON string (for household simulations)
+    """
+
+    payload = request.json
+    if payload is None:
+        raise BadRequest("Payload missing from request")
+
+    # Extract fields
+    simulation_id = payload.get("id")
+    output_json = payload.get("output_json")
+    print(f"Updating simulation #{simulation_id} for country {country_id}")
+
+    # Validate that id is provided
+    if simulation_id is None:
+        raise BadRequest("id is required")
+    if not isinstance(simulation_id, int):
+        raise BadRequest("id must be an integer")
+
+    # Validate that at least one field is being updated
+    if output_json is None:
+        raise BadRequest("output_json must be provided for update")
+
+    try:
+        # First check if the simulation exists
+        existing_simulation = simulation_service.get_simulation(
+            country_id, simulation_id
+        )
+        if existing_simulation is None:
+            raise NotFound(f"Simulation #{simulation_id} not found.")
+
+        # Update the simulation
+        success = simulation_service.update_simulation_output(
+            country_id=country_id,
+            simulation_id=simulation_id,
+            output_json=output_json,
+        )
+
+        if not success:
+            raise BadRequest("No fields to update")
+
+        # Get the updated record
+        updated_simulation = simulation_service.get_simulation(
+            country_id, simulation_id
+        )
+
+        response_body = dict(
+            status="ok",
+            message="Simulation updated successfully",
+            result=updated_simulation,
+        )
+
+        return Response(
+            json.dumps(response_body),
+            status=200,
+            mimetype="application/json",
+        )
+
+    except NotFound:
+        raise
+    except Exception as e:
+        print(f"Error updating simulation: {str(e)}")
+        raise BadRequest(f"Failed to update simulation: {str(e)}")
diff --git a/policyengine_api/services/simulation_service.py b/policyengine_api/services/simulation_service.py
index efa4d0b7..39027691 100644
--- a/policyengine_api/services/simulation_service.py
+++ b/policyengine_api/services/simulation_service.py
@@ -134,3 +134,58 @@ def get_simulation(
                 f"Error fetching simulation #{simulation_id}. Details: {str(e)}"
             )
             raise e
+
+    def update_simulation_output(
+        self,
+        country_id: str,
+        simulation_id: int,
+        output_json: str | None = None,
+    ) -> bool:
+        """
+        Update a simulation record with calculation output.
+
+        Args:
+            country_id (str): The country ID.
+            simulation_id (int): The simulation ID.
+            output_json (str | None): The output as JSON string (for household simulations).
+
+        Returns:
+            bool: True if update was successful.
+        """
+        print(f"Updating simulation {simulation_id} with output")
+        # Automatically update api_version on every update to latest
+        api_version: str = COUNTRY_PACKAGE_VERSIONS.get(country_id)
+
+        try:
+            # Build the update query dynamically based on provided fields
+            update_fields = []
+            update_values = []
+
+            if output_json is not None:
+                update_fields.append("output_json = ?")
+                # Output is already a JSON string from frontend
+                update_values.append(output_json)
+
+            # Always update API version
+            update_fields.append("api_version = ?")
+            update_values.append(api_version)
+
+            if not update_fields:
+                print("No fields to update")
+                return False
+
+            # Add simulation_id to the end of values for WHERE clause
+            update_values.append(simulation_id)
+
+            query = f"UPDATE simulations SET {', '.join(update_fields)} WHERE id = ?"
+
+            database.query(query, tuple(update_values))
+
+            print(f"Successfully updated simulation #{simulation_id}")
+            return True
+
+        except Exception as e:
+            print(
+                f"Error updating simulation #{simulation_id}. Details: {str(e)}"
+            )
+            raise e