diff --git a/ZUGFeRD.Test/XRechnungUBLTests.cs b/ZUGFeRD.Test/XRechnungUBLTests.cs
index 93c30c3d..fbfb2cd8 100644
--- a/ZUGFeRD.Test/XRechnungUBLTests.cs
+++ b/ZUGFeRD.Test/XRechnungUBLTests.cs
@@ -127,6 +127,36 @@ public void TestParentLineId()
         }
 
 
+        [TestMethod]
+        public void TestTaxRepresentativePartyNoNestedPartyElement()
+        {
+            InvoiceDescriptor desc = this._InvoiceProvider.CreateInvoice();
+            desc.SellerTaxRepresentative = new Party()
+            {
+                Name = "Tax Rep GmbH",
+                Postcode = "12345",
+                City = "Berlin",
+                Country = CountryCodes.DE
+            };
+            desc.AddSellerTaxRepresentativeTaxRegistration("DE999999999", TaxRegistrationSchemeID.VA);
+
+            MemoryStream ms = new MemoryStream();
+            desc.Save(ms, ZUGFeRDVersion.Version23, Profile.XRechnung, ZUGFeRDFormats.UBL);
+
+            // Verify XML structure: TaxRepresentativeParty must NOT contain nested cac:Party
+            string content = Encoding.UTF8.GetString(ms.ToArray());
+            Assert.IsTrue(content.Contains("<cac:TaxRepresentativeParty>"), "TaxRepresentativeParty element should exist");
+            Assert.IsFalse(Regex.IsMatch(content, @"<cac:TaxRepresentativeParty>\s*<cac:Party>"),
+                "TaxRepresentativeParty must not contain nested cac:Party element (UBL schema)");
+
+            // Verify roundtrip
+            ms.Seek(0, SeekOrigin.Begin);
+            InvoiceDescriptor loadedInvoice = InvoiceDescriptor.Load(ms);
+            Assert.IsNotNull(loadedInvoice.SellerTaxRepresentative);
+            Assert.AreEqual("Tax Rep GmbH", loadedInvoice.SellerTaxRepresentative.Name);
+        }
+
+
         [TestMethod]
         public void TestInvoiceCreation()
         {
diff --git a/ZUGFeRD/InvoiceDescriptor22UBLWriter.cs b/ZUGFeRD/InvoiceDescriptor22UBLWriter.cs
index 9f89983e..2c6d3866 100644
--- a/ZUGFeRD/InvoiceDescriptor22UBLWriter.cs
+++ b/ZUGFeRD/InvoiceDescriptor22UBLWriter.cs
@@ -956,7 +956,9 @@ private void _writeOptionalParty(ProfileAwareXmlTextWriter writer, PartyTypes pa
                         //    break;
                 }
 
-                writer.WriteStartElement("cac", "Party", this._Descriptor.Profile);
+                // TaxRepresentativeParty is already of type PartyType in UBL, no nested cac:Party needed
+                if (partyType != PartyTypes.SellerTaxRepresentativeTradeParty)
+                    writer.WriteStartElement("cac", "Party", this._Descriptor.Profile);
 
                 if (ElectronicAddress != null)
                 {
@@ -1096,8 +1098,9 @@ private void _writeOptionalParty(ProfileAwareXmlTextWriter writer, PartyTypes pa
                     writer.WriteEndElement(); // !Contact
                 }
 
-                writer.WriteEndElement(); //!Party
-                _Writer.WriteEndElement(); //Invoice
+                if (partyType != PartyTypes.SellerTaxRepresentativeTradeParty)
+                    writer.WriteEndElement(); //!Party
+                _Writer.WriteEndElement(); //!*TradeParty
             }
         } // !_writeOptionalParty()
 
diff --git a/ZUGFeRD/InvoiceDescriptor22UblReader.cs b/ZUGFeRD/InvoiceDescriptor22UblReader.cs
index 3e00132d..f086056d 100644
--- a/ZUGFeRD/InvoiceDescriptor22UblReader.cs
+++ b/ZUGFeRD/InvoiceDescriptor22UblReader.cs
@@ -197,7 +197,8 @@ public override InvoiceDescriptor Load(Stream stream)
                 };
             }
 
-            retval.SellerTaxRepresentative = _nodeAsParty(doc.DocumentElement, "//cac:TaxRepresentativeParty/cac:Party", nsmgr);
+            // TaxRepresentativeParty is directly of type PartyType in UBL, no nested cac:Party
+            retval.SellerTaxRepresentative = _nodeAsParty(doc.DocumentElement, "//cac:TaxRepresentativeParty", nsmgr);
 
             //Get all referenced and embedded documents (BG-24)
             // TODO //XmlNodeList referencedDocNodes = doc.SelectNodes(".//ram:ApplicableHeaderTradeAgreement/ram:AdditionalReferencedDocument", nsmgr);
@@ -732,9 +733,10 @@ private static List<TradeLineItem> _parseTradeLineItem(XmlNode tradeLineItem, Xm
             //Add main item to result list
             resultList.Add(item);
 
-            //Find sub invoice lines recursively
-            //Note that selectnodes also select the sub invoice line from other nodes
-            XmlNodeList subInvoiceLineNodes = tradeLineItem.SelectNodes(".//cac:SubInvoiceLine", nsmgr);
+            //Find sub invoice lines recursively - use direct children only (not .//)
+            //to avoid capturing grandchildren which would cause duplicate entries with wrong ParentLineIDs
+            string subSelector = isInvoice ? "cac:SubInvoiceLine" : "cac:SubCreditNoteLine";
+            XmlNodeList subInvoiceLineNodes = tradeLineItem.SelectNodes(subSelector, nsmgr);
             foreach (XmlNode subInvoiceLineNode in subInvoiceLineNodes)
             {
                 List<TradeLineItem> parseResultList = _parseTradeLineItem(subInvoiceLineNode, nsmgr, item.AssociatedDocument.LineID);