diff --git a/History.md b/History.md
index acad4361..44209a82 100644
--- a/History.md
+++ b/History.md
@@ -1,3 +1,9 @@
+#820/801/815
+#822
+#843
+add getCalculation on calculatedInvoice
+Transactioncalculator getTaxDetails to include correct percentage, calculated amounts
+
 2.16.5
 =======
 2025-05-22
diff --git a/doc/development_documentation.md b/doc/development_documentation.md
index dbdc8ed4..c08c457c 100644
--- a/doc/development_documentation.md
+++ b/doc/development_documentation.md
@@ -184,11 +184,11 @@ maybe not yet even existing new release version:
 
 ```
 cd validator/target
-mvn install:install-file -Dfile=validator-2.12.0-SNAPSHOT-shaded.jar -Dclassifier=shaded -DgroupId=org.mustangproject -DartifactId=validator -Dversion=2.12.0 -Dpackaging=jar -DgeneratePom=true
+mvn install:install-file -Dfile=validator-2.17.0-SNAPSHOT-shaded.jar -Dclassifier=shaded -DgroupId="org.mustangproject" -DartifactId=validator -Dversion="2.17.0" -Dpackaging=jar -DgeneratePom=true
 ```
 In gradle you can use something like
 ```
-implementation files('libs/validator-2.12.0-shaded.jar')
+implementation files('libs/validator-2.17.0-shaded.jar')
 ```
 
 
diff --git a/library/src/main/java/org/mustangproject/CalculatedInvoice.java b/library/src/main/java/org/mustangproject/CalculatedInvoice.java
index 194441b1..f993db83 100644
--- a/library/src/main/java/org/mustangproject/CalculatedInvoice.java
+++ b/library/src/main/java/org/mustangproject/CalculatedInvoice.java
@@ -19,9 +19,10 @@ public class CalculatedInvoice extends Invoice implements Serializable {
 	protected BigDecimal duePayable=null;
 	protected BigDecimal grandTotal=null;
 	protected BigDecimal taxBasis=null;
+	protected TransactionCalculator tc=null;
 
     public void calculate() {
-        TransactionCalculator tc=new TransactionCalculator(this);
+		tc=new TransactionCalculator(this);
         grandTotal=tc.getGrandTotal();
 		lineTotalAmount=tc.getValue();
 		duePayable=tc.getDuePayable();
@@ -33,6 +34,13 @@ public class CalculatedInvoice extends Invoice implements Serializable {
 		}
 		return grandTotal;
 	}
+
+
+	/***
+	 * usually one would use calculate, use only if the invoice is parsed
+	 * @param grand the gross total
+	 * @return fluent setter
+	 */
 	public CalculatedInvoice setGrandTotal(BigDecimal grand) {
 		grandTotal=grand;
 		return this;
@@ -43,6 +51,13 @@ public class CalculatedInvoice extends Invoice implements Serializable {
 		}
 		return taxBasis;
 	}
+
+
+	/***
+	 * usually one would use calculate, use only if the invoice is parsed
+	 * @param basis taxable net total
+	 * @return fluent setter
+	 */
 	public CalculatedInvoice setTaxBasis(BigDecimal basis) {
 		taxBasis=basis;
 		return this;
@@ -54,6 +69,13 @@ public class CalculatedInvoice extends Invoice implements Serializable {
 		}
 		return duePayable;
 	}
+
+
+	/***
+	 * usually one would use calculate, use only if the invoice is parsed
+	 * @param due the gross total minus prepaid
+	 * @return fluent setter
+	 */
 	public CalculatedInvoice setDuePayable(BigDecimal due) {
 		duePayable=due;
 		return this;
@@ -65,9 +87,24 @@ public class CalculatedInvoice extends Invoice implements Serializable {
 		}
 		return lineTotalAmount;
 	}
+
+	/***
+	 * usually one would use calculate, use only if the invoice is parsed
+	 * @param total the net total
+	 * @return fluent setter
+	 */
 	public CalculatedInvoice setLineTotalAmount(BigDecimal total) {
 		lineTotalAmount=total;
 		return this;
 	}
 
+	/**
+	 * this can be used to additionally e.g. access the VAT amounts
+	 * @return a updated transactioncalulator
+	 */
+	public TransactionCalculator getCalculation() {
+		calculate();
+		return tc;
+	}
+
 }
diff --git a/library/src/main/java/org/mustangproject/ZUGFeRD/TransactionCalculator.java b/library/src/main/java/org/mustangproject/ZUGFeRD/TransactionCalculator.java
index b8844b63..4f95773c 100644
--- a/library/src/main/java/org/mustangproject/ZUGFeRD/TransactionCalculator.java
+++ b/library/src/main/java/org/mustangproject/ZUGFeRD/TransactionCalculator.java
@@ -79,7 +79,7 @@ public class TransactionCalculator implements IAbsoluteValueProvider {
 					entry.getValue().getBasis(),
 					entry.getValue().getCalculated(),
 					entry.getValue().getCategoryCode()
-				).setCalculated(entry.getKey())
+				).setApplicablePercent(entry.getKey())
 			)
 			.collect(Collectors.toSet());
 	}
@@ -187,9 +187,8 @@ public class TransactionCalculator implements IAbsoluteValueProvider {
 
 		for (IZUGFeRDExportableItem currentItem : trans.getZFItems()) {
 			BigDecimal percent = null;
-			if (currentItem.getProduct()!=null)
-			{
-				percent=currentItem.getProduct().getVATPercent();
+			if (currentItem.getProduct() != null) {
+				percent = currentItem.getProduct().getVATPercent();
 			}
 			if (percent != null) {
 				LineCalculator lc = new LineCalculator(currentItem);