diff --git a/VERSION b/VERSION
index f7fb770..1e71de9 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.3.28
+2.3.29
diff --git a/app/modules/invoice_error_finder/services/economic_import_service.py b/app/modules/invoice_error_finder/services/economic_import_service.py
index 7270eb5..a67cabc 100644
--- a/app/modules/invoice_error_finder/services/economic_import_service.py
+++ b/app/modules/invoice_error_finder/services/economic_import_service.py
@@ -215,10 +215,10 @@ class EconomicImportService:
                     self._safe_str(product.get("productNumber"), 100),
                     self._safe_str(product.get("name"), 500),
                     line.get("description"),
-                    self._parse_amount(line.get("quantity")),
-                    self._parse_amount(line.get("unitNetPrice")),
-                    self._parse_amount(line.get("totalNetAmount")),
-                    self._parse_amount(line.get("discountPercentage")),
+                    self._parse_amount(line.get("quantity"), default=0.0),
+                    self._parse_amount(line.get("unitNetPrice"), default=0.0),
+                    self._parse_amount(line.get("totalNetAmount"), default=0.0),
+                    self._parse_amount(line.get("discountPercentage"), default=0.0),
                     json.dumps(line, ensure_ascii=False, default=str),
                 ),
             )
@@ -274,13 +274,13 @@ class EconomicImportService:
             return None
 
     @staticmethod
-    def _parse_amount(value: Any) -> Optional[float]:
+    def _parse_amount(value: Any, default: Optional[float] = None) -> Optional[float]:
         if value is None or value == "":
-            return None
+            return default
         try:
             return float(value)
         except (TypeError, ValueError):
-            return None
+            return default
 
     @staticmethod
     def _safe_str(value: Any, max_length: int) -> Optional[str]:
diff --git a/tests/test_invoice_error_finder.py b/tests/test_invoice_error_finder.py
index 5d8a30e..0c82ee8 100644
--- a/tests/test_invoice_error_finder.py
+++ b/tests/test_invoice_error_finder.py
@@ -74,6 +74,43 @@ def test_economic_import_service_persists_valid_json(monkeypatch):
     assert json.loads(captured["invoice_raw"])["bookedInvoiceNumber"] == 123
 
 
+def test_economic_import_service_defaults_missing_line_amounts(monkeypatch):
+    from app.modules.invoice_error_finder.services.economic_import_service import EconomicImportService
+
+    captured = []
+
+    def fake_execute_query(query, params=None):
+        if "INSERT INTO invoice_error_finder_economic_invoice_lines" in query:
+            captured.append(params)
+        return []
+
+    monkeypatch.setattr(
+        "app.modules.invoice_error_finder.services.economic_import_service.execute_query",
+        fake_execute_query,
+    )
+
+    service = EconomicImportService()
+    service._persist_lines(
+        99,
+        [
+            {
+                "lineNumber": 1,
+                "description": "Mobilnummer",
+                "quantity": None,
+                "unitNetPrice": None,
+                "totalNetAmount": None,
+                "discountPercentage": None,
+            }
+        ],
+    )
+
+    assert len(captured) == 1
+    assert captured[0][5] == 0.0
+    assert captured[0][6] == 0.0
+    assert captured[0][7] == 0.0
+    assert captured[0][8] == 0.0
+
+
 def test_detection_service_keeps_customers_without_subscriptions(monkeypatch):
     from app.modules.invoice_error_finder.services.detection_service import DetectionService