diff --git a/Elwig/Helpers/Billing/BillingData.cs b/Elwig/Helpers/Billing/BillingData.cs
index 94bc815..d59e4e4 100644
--- a/Elwig/Helpers/Billing/BillingData.cs
+++ b/Elwig/Helpers/Billing/BillingData.cs
@@ -124,6 +124,7 @@ namespace Elwig.Helpers.Billing {
                 var obj = c?.AsObject() ?? throw new InvalidOperationException();
                 var id = obj["id"]?.GetValue<int>() ?? throw new InvalidOperationException();
                 var cMode = (obj["mode"]?.GetValue<string>() == "kmw") ? CurveMode.Kmw : CurveMode.Oe;
+                double quw = cMode == CurveMode.Oe ? 73 : 15;
 
                 Dictionary<double, decimal> c1;
                 Dictionary<double, decimal>? c2 = null;
@@ -131,7 +132,7 @@ namespace Elwig.Helpers.Billing {
                 if (norm is JsonObject) {
                     c1 = GetCurveData(norm.AsObject(), cMode);
                 } else if (norm?.AsValue().TryGetValue(out decimal v) == true) {
-                    c1 = new() { { cMode == CurveMode.Oe ? 73 : 15, v } };
+                    c1 = new() { { quw, v } };
                 } else {
                     throw new InvalidOperationException();
                 }
@@ -139,7 +140,10 @@ namespace Elwig.Helpers.Billing {
                 if (geb is JsonObject) {
                     c2 = GetCurveData(geb.AsObject(), cMode);
                 } else if (geb?.AsValue().TryGetValue(out decimal v) == true) {
-                    c2 = c1.ToDictionary(e => e.Key, e => e.Value + v);
+                    var splitVal = GetCurveValueAt(c1, quw);
+                    c2 = c1.ToDictionary(e => e.Key, e => e.Value + (e.Key >= quw ? v : 0));
+                    c2[quw] = splitVal + v;
+                    c2[Math.BitDecrement(quw)] = splitVal;
                 }
                 dict.Add(id, new(cMode, c1, c2));
             }
@@ -181,5 +185,25 @@ namespace Elwig.Helpers.Billing {
 
             return dict;
         }
+
+        public static decimal GetCurveValueAt(Dictionary<double, decimal> curve, double key) {
+            if (curve.Count == 1) return curve.First().Value;
+
+            var lt = curve.Keys.Where(v => v <= key);
+            var gt = curve.Keys.Where(v => v >= key);
+            if (!lt.Any()) {
+                return curve[gt.Min()];
+            } else if (!gt.Any()) {
+                return curve[lt.Max()];
+            }
+
+            var max = lt.Max();
+            var min = gt.Min();
+            if (max == min) return curve[key];
+
+            var p1 = ((decimal)key - (decimal)min) / ((decimal)max - (decimal)min);
+            var p2 = 1 - p1;
+            return curve[min] * p2 + curve[max] * p1;
+        }
     }
 }
diff --git a/Elwig/Helpers/Billing/PaymentBillingData.cs b/Elwig/Helpers/Billing/PaymentBillingData.cs
index 0c1535d..75f622a 100644
--- a/Elwig/Helpers/Billing/PaymentBillingData.cs
+++ b/Elwig/Helpers/Billing/PaymentBillingData.cs
@@ -49,25 +49,7 @@ namespace Elwig.Helpers.Billing {
 
         public decimal CalculatePrice(string sortid, string? attrid, string qualid, bool gebunden, double oe, double kmw) {
             var curve = GetQualityCurve(qualid, sortid, attrid) ?? GetCurve(sortid, attrid);
-            var d = (gebunden ? curve.Gebunden : null) ?? curve.Normal;
-            if (d.Count == 1) return d.First().Value;
-
-            var r = curve.Mode == CurveMode.Oe ? oe : kmw;
-            var lt = d.Keys.Where(v => v <= r);
-            var gt = d.Keys.Where(v => v >= r);
-            if (!lt.Any()) {
-                return d[gt.Min()];
-            } else if (!gt.Any()) {
-                return d[lt.Max()];
-            }
-
-            var max = lt.Max();
-            var min = gt.Min();
-            if (max == min) return d[r];
-
-            var p1 = ((decimal)r - (decimal)min) / ((decimal)max - (decimal)min);
-            var p2 = 1 - p1;
-            return d[min] * p2 + d[max] * p1;
+            return GetCurveValueAt((gebunden ? curve.Gebunden : null) ?? curve.Normal, curve.Mode == CurveMode.Oe ? oe : kmw);
         }
 
         private Curve LookupCurve(JsonValue val) {