diff --git a/Elwig/Helpers/Billing/PaymentBillingData.cs b/Elwig/Helpers/Billing/PaymentBillingData.cs
index 696258d..bf45ef1 100644
--- a/Elwig/Helpers/Billing/PaymentBillingData.cs
+++ b/Elwig/Helpers/Billing/PaymentBillingData.cs
@@ -70,6 +70,7 @@ namespace Elwig.Helpers.Billing {
         protected Dictionary<string, Curve> GetQualityData() {
             Dictionary<string, Curve> dict = [];
             var q = GetQualityEntry();
+            if (q == null) return dict;
 
             foreach (var (qualid, data) in q) {
                 Dictionary<string, Curve> qualDict;
diff --git a/Tests/Helpers/BillingDataTest.cs b/Tests/Helpers/BillingDataTest.cs
index 79f260e..dd6dfac 100644
--- a/Tests/Helpers/BillingDataTest.cs
+++ b/Tests/Helpers/BillingDataTest.cs
@@ -26,14 +26,14 @@ namespace Tests.Helpers {
             };
         }
 
-        private static void TestCalcOe(BillingData data, string bucket, double oe, decimal expected, string? qualid = null, bool geb = false) {
+        private static void TestCalcOe(PaymentBillingData data, string bucket, double oe, decimal expected, string? qualid = null, bool geb = false) {
             var (sortid, attrid) = GetSortIdAttrId(bucket);
             var kmw = Utils.OeToKmw(oe);
             var v = data.CalculatePrice(sortid, attrid, qualid ?? GetQualId(kmw), geb, oe, kmw);
             Assert.That(Math.Round(v, 6), Is.EqualTo(expected));
         }
 
-        private static void TestCalcKmw(BillingData data, string bucket, double kmw, decimal expected, string? qualid = null, bool geb = false) {
+        private static void TestCalcKmw(PaymentBillingData data, string bucket, double kmw, decimal expected, string? qualid = null, bool geb = false) {
             var (sortid, attrid) = GetSortIdAttrId(bucket);
             var oe = Utils.KmwToOe(kmw);
             var v = data.CalculatePrice(sortid, attrid, qualid ?? GetQualId(kmw), geb, oe, kmw);
@@ -42,7 +42,7 @@ namespace Tests.Helpers {
 
         [Test]
         public void Test_01_Flatrate() {
-            var data = BillingData.FromJson("""
+            var data = PaymentBillingData.FromJson("""
                 {
                   "mode": "elwig",
                   "version": 1,
@@ -58,7 +58,7 @@ namespace Tests.Helpers {
 
         [Test]
         public void Test_02_Simple() {
-            var data = BillingData.FromJson("""
+            var data = PaymentBillingData.FromJson("""
                 {
                   "mode": "elwig",
                   "version": 1,
@@ -93,7 +93,7 @@ namespace Tests.Helpers {
 
         [Test]
         public void Test_03_GreaterThanAndLessThan() {
-            var data = BillingData.FromJson("""
+            var data = PaymentBillingData.FromJson("""
                 {
                   "mode": "elwig",
                   "version": 1,
@@ -132,7 +132,7 @@ namespace Tests.Helpers {
 
         [Test]
         public void Test_04_VariantsAndAttributes() {
-            var data = BillingData.FromJson("""
+            var data = PaymentBillingData.FromJson("""
                 {
                   "mode": "elwig",
                   "version": 1,
@@ -162,7 +162,7 @@ namespace Tests.Helpers {
 
         [Test]
         public void Test_05_QualityLevel() {
-            var data = BillingData.FromJson("""
+            var data = PaymentBillingData.FromJson("""
                 {
                   "mode": "elwig",
                   "version": 1,
@@ -193,7 +193,7 @@ namespace Tests.Helpers {
 
         [Test]
         public void Test_06_ModeOeAndKmw() {
-            var data = BillingData.FromJson("""
+            var data = PaymentBillingData.FromJson("""
                 {
                   "mode": "elwig",
                   "version": 1,
@@ -235,7 +235,7 @@ namespace Tests.Helpers {
 
         [Test]
         public void Test_07_MultipleCurves() {
-            var data = BillingData.FromJson("""
+            var data = PaymentBillingData.FromJson("""
                 {
                   "mode": "elwig",
                   "version": 1,
@@ -304,7 +304,7 @@ namespace Tests.Helpers {
 
         [Test]
         public void Test_08_WgMaster() {
-            var data = BillingData.FromJson("""
+            var data = PaymentBillingData.FromJson("""
                 {
                   "mode": "wgmaster",
                   "Grundbetrag": 0.033,