diff --git a/library/src/main/java/org/mustangproject/Invoice.java b/library/src/main/java/org/mustangproject/Invoice.java
index 583c406a..f09a2344 100644
--- a/library/src/main/java/org/mustangproject/Invoice.java
+++ b/library/src/main/java/org/mustangproject/Invoice.java
@@ -33,6 +33,7 @@ public class Invoice implements IExportableTransaction {
 	protected BigDecimal totalPrepaidAmount = null;
 	protected IZUGFeRDExportableContact ownContact = null, recipient = null, deliveryAddress = null;
 	protected ArrayList<IZUGFeRDExportableItem> ZFItems = null;
+	protected String contractReferencedDocument = null;
 
 	protected ArrayList<IZUGFeRDAllowanceCharge> Allowances = new ArrayList<IZUGFeRDAllowanceCharge>(),
 			Charges = new ArrayList<IZUGFeRDAllowanceCharge>(), LogisticsServiceCharges = new ArrayList<IZUGFeRDAllowanceCharge>();
@@ -50,6 +51,8 @@ public class Invoice implements IExportableTransaction {
 		return documentName;
 	}
 
+	public String getContractReferencedDocument() { return contractReferencedDocument; }
+
 	public Invoice setDocumentName(String documentName) {
 		this.documentName = documentName;
 		return this;
@@ -419,4 +422,9 @@ public class Invoice implements IExportableTransaction {
 		Allowances.add(izac);
 		return this;
 	}
+
+	public Invoice setContractReferencedDocument(String s) {
+		contractReferencedDocument=s;
+		return this;
+	}
 }
diff --git a/library/src/main/java/org/mustangproject/ZUGFeRD/IExportableTransaction.java b/library/src/main/java/org/mustangproject/ZUGFeRD/IExportableTransaction.java
index e4c89071..37b3970e 100644
--- a/library/src/main/java/org/mustangproject/ZUGFeRD/IExportableTransaction.java
+++ b/library/src/main/java/org/mustangproject/ZUGFeRD/IExportableTransaction.java
@@ -95,6 +95,10 @@ public interface IExportableTransaction {
 		return null;
 	}
 
+	default String getContractReferencedDocument() {
+		return null;
+	}
+
 
 	/**
 	 * who processed the order
diff --git a/library/src/test/java/org/mustangproject/ZUGFeRD/ZF2PushTest.java b/library/src/test/java/org/mustangproject/ZUGFeRD/ZF2PushTest.java
index e4ad96a6..57d15585 100644
--- a/library/src/test/java/org/mustangproject/ZUGFeRD/ZF2PushTest.java
+++ b/library/src/test/java/org/mustangproject/ZUGFeRD/ZF2PushTest.java
@@ -51,7 +51,7 @@ public class ZF2PushTest extends TestCase {
 					 .setCreator(System.getProperty("user.name")).setZUGFeRDVersion(2).ignorePDFAErrors()
 					 .load(SOURCE_PDF)) {
 
-			ze.setTransaction(new Invoice().setDueDate(new Date()).setIssueDate(new Date()).setDeliveryDate(new Date()).setOwnOrganisationName(orgname).setOwnStreet("teststr").setOwnZIP("55232").setOwnLocation("teststadt").setOwnCountry("DE").setOwnTaxID("4711").setOwnVATID("DE19990815").setRecipient(new Contact("Franz Müller", "0177123456", "fmueller@test.com", "teststr.12", "55232", "Entenhausen", "DE")).setNumber(number).addItem(new Item(new Product("Testprodukt", "", "C62", new BigDecimal(0)), amount, new BigDecimal(1.0))));
+			ze.setTransaction(new Invoice().setDueDate(new Date()).setIssueDate(new Date()).setDeliveryDate(new Date()).setContractReferencedDocument("0815").setOwnOrganisationName(orgname).setOwnStreet("teststr").setOwnZIP("55232").setOwnLocation("teststadt").setOwnCountry("DE").setOwnTaxID("4711").setOwnVATID("DE19990815").setRecipient(new Contact("Franz Müller", "0177123456", "fmueller@test.com", "teststr.12", "55232", "Entenhausen", "DE")).setNumber(number).addItem(new Item(new Product("Testprodukt", "", "C62", new BigDecimal(0)), amount, new BigDecimal(1.0))));
 			String theXML = new String(ze.getProvider().getXML());
 			assertTrue(theXML.contains("<rsm:CrossIndustryInvoice"));
 			ze.export(TARGET_PDF);
@@ -63,6 +63,7 @@ public class ZF2PushTest extends TestCase {
 		ZUGFeRDImporter zi = new ZUGFeRDImporter(TARGET_PDF);
 
 		assertTrue(zi.getUTF8().contains("EUR"));
+		assertTrue(zi.getUTF8().contains("0815"));
 
 		// Reading ZUGFeRD
 		assertEquals(amountStr, zi.getAmount());