diff --git a/ReportImp/SBBMainzReports/Invoicing/CustomInvoiceCreationQA.cs b/ReportImp/SBBMainzReports/Invoicing/CustomInvoiceCreationQA.cs
index 3bc990e23..0ca490ca9 100644
--- a/ReportImp/SBBMainzReports/Invoicing/CustomInvoiceCreationQA.cs
+++ b/ReportImp/SBBMainzReports/Invoicing/CustomInvoiceCreationQA.cs
@@ -116,25 +116,41 @@ namespace SBBMainzReports.Invoicing
             {
                 decimal? hourlyRate = cr.CostRateValue.Value;
                 decimal weeklyFactor = 4.33m;
-                if (scap.StartDate.HasValue && scap.StartDate.Value.Day > 7)
+                // Anteilige Berechnung nur in dem Monat, in dem der HP tatsächlich beginnt bzw. endet -
+                // in allen anderen (vollen) Monaten wird der volle Monatsfaktor berechnet
+                if (scap.StartDate.HasValue && scap.StartDate.Value.Day > 7 && serviceInvoicePeriod.Start.HasValue
+                    && scap.StartDate.Value.Year == serviceInvoicePeriod.Start.Value.Year && scap.StartDate.Value.Month == serviceInvoicePeriod.Start.Value.Month)
                 {
                     int startDay = scap.StartDate.Value.Day;
                     if (startDay <= 14)
+                    {
                         weeklyFactor = Math.Min(weeklyFactor, 3m);
+                    }
                     else if (startDay <= 21)
+                    {
                         weeklyFactor = Math.Min(weeklyFactor, 2m);
+                    }
                     else
+                    {
                         weeklyFactor = Math.Min(weeklyFactor, 1m);
+                    }
                 }
-                if (scap.EndDate.HasValue && scap.EndDate.Value.Day < 22)
+                if (scap.EndDate.HasValue && scap.EndDate.Value.Day < 22 && serviceInvoicePeriod.End.HasValue
+                    && scap.EndDate.Value.Year == serviceInvoicePeriod.End.Value.Year && scap.EndDate.Value.Month == serviceInvoicePeriod.End.Value.Month)
                 {
                     int endDay = scap.EndDate.Value.Day;
                     if (endDay >= 15)
+                    {
                         weeklyFactor = Math.Min(weeklyFactor, 3m);
+                    }
                     else if (endDay >= 8)
+                    {
                         weeklyFactor = Math.Min(weeklyFactor, 2m);
+                    }
                     else
+                    {
                         weeklyFactor = Math.Min(weeklyFactor, 1m);
+                    }
                 }
 
                 decimal approvedHours = 0;
@@ -142,7 +158,7 @@ namespace SBBMainzReports.Invoicing
                 if (scap.ApprovedBEInterval.HasValue && scap.ApprovedBEInterval.Value == SupportConceptApprovalInterval.Weekly && scap.ApprovedBEPerInterval.HasValue)
                 {
                     approvedHours = scap.ApprovedBEPerInterval.Value;
-                    approvedHoursMonth = Math.Round(weeklyFactor * scap.ApprovedBEPerInterval.Value, 2, MidpointRounding.AwayFromZero);
+                    approvedHoursMonth = weeklyFactor * scap.ApprovedBEPerInterval.Value;
                 }
                 decimal amount = approvedHoursMonth * hourlyRate.Value;
                 serviceInvoicePeriod.InvoiceItemList.Add(new InvoiceItem