diff --git a/BeWo/View/Detail/Accounting/ServiceInvoiceCreatePopUpView.xaml b/BeWo/View/Detail/Accounting/ServiceInvoiceCreatePopUpView.xaml
index 34c6c7f01..082070e1e 100644
--- a/BeWo/View/Detail/Accounting/ServiceInvoiceCreatePopUpView.xaml
+++ b/BeWo/View/Detail/Accounting/ServiceInvoiceCreatePopUpView.xaml
@@ -10,7 +10,7 @@
         HorizontalAlignment="Stretch" xmlns:s="clr-namespace:System;assembly=mscorlib" xmlns:r="clr-namespace:BeWo.Security"
         VerticalAlignment="Stretch" Focusable="True"
         xmlns:Microsoft_Windows_Themes="clr-namespace:Microsoft.Windows.Themes;assembly=PresentationFramework.Classic">
-    <GroupBox Width="850" Style="{StaticResource PopUpWindowStyle}">
+    <GroupBox Width="1100" Style="{StaticResource PopUpWindowStyle}">
         <GroupBox.Header>
             <StackPanel Orientation="Horizontal" VerticalAlignment="Center" Margin="0,0,0,0">
                 <Image Source="..\..\Ressources\Icons\CoinsDisabled.png" Height="28" />
@@ -22,6 +22,10 @@
         <Grid Background="{StaticResource ObjectEditBackgroundBrush}">
             <GroupBox Margin="10" Header="Rechnung(en) erstellen" Style="{StaticResource ObjectEditGroupBox}">
                 <Grid>
+                    <Grid.ColumnDefinitions>
+                        <ColumnDefinition />
+                        <ColumnDefinition />
+                    </Grid.ColumnDefinitions>
                     <Grid.RowDefinitions>
                         <RowDefinition Height="Auto" />
                         <RowDefinition Height="*" />
@@ -34,7 +38,9 @@
                             <AccessText Margin="2">Klicken Sie anschließend auf "Erstellen".</AccessText>
                         </StackPanel>
                     </Label>
-                    <dxg:GridControl x:Name="grid_newInvoices" Margin="3" Grid.Row="1" MinHeight="200">
+                    <TextBlock x:Name="txtWarnhinweis" Foreground="Red" Grid.Column="1" ></TextBlock>
+
+                        <dxg:GridControl x:Name="grid_newInvoices" Margin="3" Grid.Row="1" Grid.ColumnSpan="2" MinHeight="200">
                         <dxg:GridControl.Columns>
                             <dxg:GridColumn FieldName="Notice" Header="" FixedWidth="True" Width="24" ReadOnly="True">
                                 <dxg:GridColumn.CellTemplate>
@@ -52,12 +58,16 @@
                                     <dxe:TextEditSettings DisplayFormat="c" Mask="c" MaskType="Numeric"></dxe:TextEditSettings>
                                 </dxg:GridColumn.EditSettings>
                             </dxg:GridColumn>
+                            <dxg:GridColumn FieldName="InvoiceBase.Details" Header="Details"></dxg:GridColumn>
+                            <dxg:GridColumn FieldName="InvoiceBase.NeuErstellen" Header="Neu erstellen" ></dxg:GridColumn>
+                            <dxg:GridColumn FieldName="InvoiceBase.DiffErstellen" Header="{markup:Translate Diff.-Rg erstellen}"></dxg:GridColumn>
+                            <dxg:GridColumn FieldName="InvoiceBase.Hinweise" Header="Hinweise"></dxg:GridColumn>
                         </dxg:GridControl.Columns>
                         <dxg:GridControl.View>
-                            <dxg:TableView ShowGroupPanel="False" />
+                            <dxg:TableView ShowGroupPanel="False" CellValueChanging="TableView_CellValueChanging"/>
                         </dxg:GridControl.View>
                     </dxg:GridControl>
-                    <StackPanel HorizontalAlignment="Right" Orientation="Horizontal" Grid.Row="2">
+                    <StackPanel HorizontalAlignment="Right" Orientation="Horizontal" Grid.Row="2" Grid.ColumnSpan="2">
                         <Button Content="Erstellen" x:Name="btn_create" Click="btn_create_Click" Padding="5 0" Margin="3" />
                         <Button Content="Abbrechen" x:Name="btn_cancel" Click="btn_cancel_Click" Margin="3" Padding="5 0" />
                     </StackPanel>
diff --git a/BeWo/View/Detail/Accounting/ServiceInvoiceCreatePopUpView.xaml.cs b/BeWo/View/Detail/Accounting/ServiceInvoiceCreatePopUpView.xaml.cs
index 0b65dbbec..69f700742 100644
--- a/BeWo/View/Detail/Accounting/ServiceInvoiceCreatePopUpView.xaml.cs
+++ b/BeWo/View/Detail/Accounting/ServiceInvoiceCreatePopUpView.xaml.cs
@@ -8,7 +8,7 @@ using System.Windows.Input;
 using BS.Shared.Core;
 using BS.Shared.DataContracts;
 using BS.Shared.Extensions;
-
+using BS.Shared.Translation;
 using DevExpress.Xpf.Grid;
 
 namespace BeWo.View.Detail.Accounting
@@ -42,6 +42,16 @@ namespace BeWo.View.Detail.Accounting
                 this._InvoiceNumbers = value.Select(i => i.InvoiceBase.InvoiceNumber).ToList();
                 this._Dcs = new BindingList<ServiceInvoiceDC>(value);
                 this.grid_newInvoices.ItemsSource = this._Dcs;
+
+                SetzeWarnhinweis();
+            }
+        }
+
+        private void SetzeWarnhinweis()
+        {
+            if (_Dcs.Any(s => s.InvoiceBase.DiffErstellen))
+            {
+                txtWarnhinweis.Text = Translator.Translate("Es wurden bereits Rechnungen im gewählten Zeitraum erstellt.\nWenn Sie keine Differenzrechnungen erstellen möchten,\nentfernen Sie bitte die entsprechenden Häkchen.");
             }
         }
 
@@ -73,5 +83,26 @@ namespace BeWo.View.Detail.Accounting
         {
             this._Dcs.Remove(this.grid_newInvoices.GetCurrentValue<ServiceInvoiceDC>());
         }
+
+        private void TableView_CellValueChanging(object sender, CellValueChangedEventArgs e)
+        {
+            var si = e.Row as ServiceInvoiceDC;
+            if (e.Column.FieldName.Contains("NeuErstellen") && ((bool)e.Value))
+            {
+                if (si.InvoiceBase.DiffErstellen)
+                {
+                    si.InvoiceBase.DiffErstellen = false;
+                    grid_newInvoices.RefreshData();
+                }
+            }
+            else if (e.Column.FieldName.Contains("DiffErstellen") && ((bool)e.Value))
+            {
+                if (si.InvoiceBase.NeuErstellen)
+                {
+                    si.InvoiceBase.NeuErstellen = false;
+                    grid_newInvoices.RefreshData();
+                }
+            }
+        }
     }
 }
\ No newline at end of file
diff --git a/BeWo/ViewModel/InvoiceBaseVM.cs b/BeWo/ViewModel/InvoiceBaseVM.cs
index abae3fd1d..89be483a9 100644
--- a/BeWo/ViewModel/InvoiceBaseVM.cs
+++ b/BeWo/ViewModel/InvoiceBaseVM.cs
@@ -39,6 +39,10 @@ namespace BeWo.ViewModel
 
         public static string PropertyName_InvoiceTitle = "InvoiceTitle";
 
+        public static string PropertyName_NeuErstellen = "NeuErstellen";
+
+        public static string PropertyName_DiffErstellen = "DiffErstellen";
+
         public static string PropertyName_IsPaid = "IsPaid";
 
         public static string PropertyName_Notice = "Notice";
@@ -128,6 +132,10 @@ namespace BeWo.ViewModel
         private string _InvoiceTitle = string.Empty;
         internal bool _IsPaid;
 
+        internal bool _NeuErstellen;
+
+        internal bool _DiffErstellen;
+
         internal bool _IsChecked;
 
         private string _Notice = string.Empty;
@@ -406,6 +414,50 @@ namespace BeWo.ViewModel
             }
         }
 
+        public string Details
+        {
+            get { return DataContract.Details ; }
+
+            
+        }
+
+        public string Hinweise
+        {
+            get { return DataContract.Hinweise; }
+
+
+        }
+
+        public bool NeuErstellen
+        {
+            get { return _NeuErstellen; }
+
+            set
+            {
+                if (AreDifferent(_NeuErstellen, value))
+                {
+                    _NeuErstellen = value;
+                    StoreDirtyInformation(AreDifferent(DataContract.NeuErstellen, value), PropertyName_NeuErstellen);
+                    FirePropertyChanged(PropertyName_NeuErstellen);
+                }
+            }
+        }
+
+        public bool DiffErstellen
+        {
+            get { return _DiffErstellen; }
+
+            set
+            {
+                if (AreDifferent(_DiffErstellen, value))
+                {
+                    _DiffErstellen = value;
+                    StoreDirtyInformation(AreDifferent(DataContract.DiffErstellen, value), PropertyName_DiffErstellen);
+                    FirePropertyChanged(PropertyName_DiffErstellen);
+                }
+            }
+        }
+
         public bool IsPaid
         {
             get { return _IsPaid; }
@@ -847,10 +899,12 @@ namespace BeWo.ViewModel
             _RecipientCustomerOid     = pDataContract.RecipientCustomerOid;
             _RecipientCostBearerOid   = pDataContract.RecipientCostBearerOid;
             _RecipientStreet          = pDataContract.RecipientStreet;
-            _RecipientAddressLine1 = pDataContract.RecipientAddressLine1;
+            _RecipientAddressLine1    = pDataContract.RecipientAddressLine1;
             _RecipientTown            = pDataContract.RecipientTown;
             _RecipientPostCode        = pDataContract.RecipientPostCode;
             _IsPaid                   = pDataContract.IsPaid;
+            _NeuErstellen             = pDataContract.NeuErstellen;
+            _DiffErstellen            = pDataContract.DiffErstellen;
             _InvoiceTitle             = pDataContract.InvoiceTitle;
             _InvoiceNumber            = pDataContract.InvoiceNumber;
             _InvoiceDate              = pDataContract.InvoiceDate;
@@ -862,8 +916,8 @@ namespace BeWo.ViewModel
             _Notice                   = pDataContract.Notice;
             _DunningLetterCount       = pDataContract.DunningLetterCount;
             _TotalAmount              = pDataContract.TotalAmount;
-            _CustomerReferenceNumber = pDataContract.CustomerReferenceNumber;
-            BackgroundColor = pDataContract.BackgroundColor;
+            _CustomerReferenceNumber  = pDataContract.CustomerReferenceNumber;
+            BackgroundColor           = pDataContract.BackgroundColor;
 
             foreach (var iContactDC in pDataContract.SenderContactInformations)
             {
@@ -906,9 +960,11 @@ namespace BeWo.ViewModel
             pDataContract.RecipientCostBearerOid   = _RecipientCostBearerOid;
             pDataContract.RecipientPostCode        = _RecipientPostCode;
             pDataContract.RecipientStreet          = _RecipientStreet;
-            pDataContract.RecipientAddressLine1 = _RecipientAddressLine1;
+            pDataContract.RecipientAddressLine1    = _RecipientAddressLine1;
             pDataContract.RecipientTown            = _RecipientTown;
             pDataContract.IsPaid                   = _IsPaid;
+            pDataContract.NeuErstellen             = _NeuErstellen;
+            pDataContract.DiffErstellen            = _DiffErstellen;
             pDataContract.InvoiceTitle             = _InvoiceTitle;
             pDataContract.InvoiceNumber            = _InvoiceNumber;
             pDataContract.InvoiceDate              = _InvoiceDate;
@@ -920,7 +976,7 @@ namespace BeWo.ViewModel
             pDataContract.Notice                   = _Notice;
             pDataContract.DunningLetterCount       = _DunningLetterCount;
             pDataContract.TotalAmount              = _TotalAmount;
-            pDataContract.CustomerReferenceNumber = _CustomerReferenceNumber;
+            pDataContract.CustomerReferenceNumber  = _CustomerReferenceNumber;
             
             CommitSenderContact(_SenderFax, ContactType.business_Fax);
             CommitSenderContact(_SenderPhone, ContactType.business_Phone);
diff --git a/Service/Plugins/AccountingService.cs b/Service/Plugins/AccountingService.cs
index 1f0761714..19faca7e3 100644
--- a/Service/Plugins/AccountingService.cs
+++ b/Service/Plugins/AccountingService.cs
@@ -6,17 +6,178 @@ using BeWo.Data.Access;
 using BeWo.Data.Entities;
 using BeWo.Service.Core;
 using BeWo.Service.DCEntityMapper;
+using BeWo.Service.Invoicing;
 using BeWo.Service.ServiceContracts;
 using BS.Shared;
 using BS.Shared.Core;
 using BS.Shared.DataContracts;
+using BS.Shared.DataContracts.Compact;
 using BS.Shared.Extensions;
 
 namespace BeWo.Service.Plugins
 {
 	public class AccountingService : AbstractIDSpecificDefaultClass<AccountingService>
 	{
-		public virtual List<long> UpdateServiceInvoices(List<ServiceInvoiceDC> invoices)
+		public virtual List<ServiceInvoiceDC> GenerateInitialServiceInvoices(long costBearerOid, long? supportConceptOid, DateTimeSpan invoicePeriod)
+		{
+			var cs = PluginLoader.FindClass<CustomerService>();
+			IEnumerable<CompactSupportConceptDC> supportConcepts;
+			// GetAllActiveSupportConceptCostbearer returns a "Flat" SupportConcept List, one for each CostBearer2SupportConcept!
+			if (!supportConceptOid.HasValue)
+			{
+				supportConcepts = cs.GetAllActiveSupportConceptCostbearer(false, true, 0)
+					.Where(i => i.CostBearerOids2CostBearerRelOids.ContainsKey(costBearerOid));
+			}
+			else
+			{
+				supportConcepts = cs.GetCompactSupportConcepts(supportConceptOid.Value, null)
+					.Where(i => i.CostBearerOids2CostBearerRelOids.ContainsKey(costBearerOid));
+			}
+
+			DateTimeSpan newSpan = null;
+			if (invoicePeriod != null)
+			{
+				//invoicePeriod.StartDateTime = invoicePeriod.StartDateTime.Date;
+				//invoicePeriod.EndDateTime = invoicePeriod.EndDateTime.Date;
+				newSpan = new DateTimeSpan();
+				newSpan.StartDateTime = invoicePeriod.StartDateTime.Date;
+				newSpan.EndDateTime = invoicePeriod.EndDateTime.Date.AddDays(1).AddTicks(-1);
+				if (!supportConceptOid.HasValue)
+				{
+					supportConcepts =
+						supportConcepts.Where(sc => sc.StartDate < newSpan.EndDate && sc.EndDate >= newSpan.StartDate);
+				}
+			}
+			var supportConcepts2ServiceRecords = supportConcepts.ToDictionary(
+														i => i,
+														i => MapperFactory.ServiceRecordDC_ServiceRecord.MapToNewDCs(
+																													DAOFactory.SearchDAO.FindServiceRecordsInSpan(i.CostBearerRelOids[0], newSpan)));
+			var cb = DAOFactory.GenericDAO.LoadByID<CostBearer>(costBearerOid);
+			String tenant = PluginLoader.Tenant;
+			var factory = PluginLoader.FindClass<InvoiceFactory>(cb.ID);
+			if (factory == null)
+			{
+				factory = InvoiceFactory.GetInstance(cb.ID, tenant);
+			}
+
+			var creator = factory.CreateInvoiceCreator(cb.ID, tenant, supportConcepts2ServiceRecords);
+			var newInvoices = creator.GenerateServiceInvoices(costBearerOid, invoicePeriod, supportConcepts2ServiceRecords);
+
+			//Prüfe ob Rechnungen neu sind oder Diff vorhanden
+			var differenzRechnungChecks = GetNewInvoices(newInvoices, invoicePeriod.StartDate, invoicePeriod.EndDate);
+			var resultList = ErstelleNeueRechnungen(differenzRechnungChecks);
+
+			return resultList;
+		}
+
+		protected virtual List<ServiceInvoiceDC> ErstelleNeueRechnungen(List<DifferenzRechnungCheck> differenzRechnungChecks)
+        {
+			var rechnungen = new List<ServiceInvoiceDC>();
+			foreach (var item in differenzRechnungChecks)
+			{
+				if (item.VorhandeneRechungen.Count == 0)
+				{
+					item.NeueRechnung.InvoiceBase.NeuErstellen = true;
+					rechnungen.Add(item.NeueRechnung);
+				}
+				else
+				{
+					rechnungen.Add(ErstelleDifferenzRechnung(item));
+				}
+			}
+
+			return rechnungen;
+		}
+
+		protected virtual ServiceInvoiceDC ErstelleDifferenzRechnung(DifferenzRechnungCheck item)
+        {
+			ServiceInvoiceDC diffRechnung = null;
+			var alterBetrag = item.VorhandeneRechungen.Sum(i => i.ClaimSum ?? 0);
+
+            if (item.NeueRechnung.ClaimSum == alterBetrag)
+			{
+				diffRechnung = item.NeueRechnung;
+				diffRechnung.InvoiceBase.NeuErstellen = false;
+				diffRechnung.InvoiceBase.Hinweise = String.Format("Rechnung wurde bereits erstellt");
+			}
+			else
+            {
+				diffRechnung = new ServiceInvoiceDC();
+				diffRechnung.OriginalZurDifferenz = item.NeueRechnung;
+				diffRechnung.InvoiceBase = new InvoiceBaseDC();
+				CopyInvoiceBaseDC(item.NeueRechnung.InvoiceBase, diffRechnung);
+
+				var newItem = new InvoiceItemDC();
+				newItem.ItemPeriodStart = item.NeueRechnung.InvoiceBase.AccountingPeriodStart;
+				newItem.ItemPeriodEnd = item.NeueRechnung.InvoiceBase.AccountingPeriodEnd;
+				newItem.UnitCount = 1;
+				newItem.AmountPerUnit = item.NeueRechnung.ClaimSum - alterBetrag;
+				newItem.AmountTotal = newItem.AmountPerUnit;
+				newItem.GrossAmountTotal = newItem.AmountTotal;
+				newItem.ItemDescription = String.Format("Rechnungsdifferenz zu Rechnung {0} in Höhe von {1:c}", item.VorhandeneRechungen[0].InvoiceBase.InvoiceNumber, alterBetrag);
+				diffRechnung.InvoiceBase.Hinweise = String.Format("Rechnungsdifferenz zu Rechnung {0} in Höhe von {1:c}", item.VorhandeneRechungen[0].InvoiceBase.InvoiceNumber, alterBetrag);
+
+				var newSip = new ServiceInvoicePeriodDC();
+				newSip.Claim = newItem.AmountTotal;
+				newSip.Start = item.NeueRechnung.InvoiceBase.AccountingPeriodStart;
+				newSip.End = item.NeueRechnung.InvoiceBase.AccountingPeriodEnd;
+				diffRechnung.ServiceInvoicePeriods = new List<ServiceInvoicePeriodDC>();
+				diffRechnung.ServiceInvoicePeriods.Add(newSip);
+				newSip.InvoiceItems = new List<InvoiceItemDC>();
+				newSip.InvoiceItems.Add(newItem);
+            }
+			return diffRechnung;
+        }
+
+        protected virtual List<DifferenzRechnungCheck> GetNewInvoices(List<ServiceInvoiceDC> invoices, DateTime start, DateTime end)
+        {
+            List<DifferenzRechnungCheck> result = new List<DifferenzRechnungCheck>();
+            var existingInvoices = DAOFactory.SearchDAO.GetInvoiceBases(start, end, false);
+
+            foreach (var si in invoices)
+            {
+				var checkResult = new DifferenzRechnungCheck();
+				result.Add(checkResult);
+				checkResult.NeueRechnung = si;
+				checkResult.VorhandeneRechungen = new List<ServiceInvoiceDC>();
+
+                foreach (var i2 in existingInvoices.Where(i => i.Type == InvoiceType.Service))
+                {
+					if (si.InvoiceBase.SupportConceptCostBearerRelDc != null && si.InvoiceBase.SupportConceptCostBearerRelDc.CostBearer2SupportConceptOid == i2.CostBearer2SupportConceptOid)
+					{
+						var siAlt = DAOFactory.SearchDAO.GetServiceInvoiceByInvoiceBaseOid(i2.Oid.Value);
+						var siDCAlt = MapperFactory.ServiceInvoiceDC_ServiceInvoice.MapToNewDC(siAlt);
+
+						//InvoiceItems vergleichen?
+						//foreach (var sip in si.ServiceInvoicePeriods)
+						//{
+						//	foreach (var ii in sip.InvoiceItems)
+						//	{
+						//		typNeu = ii.ItemDescription;
+						//	}
+						//}
+
+						//foreach (var sip in siAlt.ServiceInvoicePeriodList)
+						//{
+						//	foreach (var ii in sip.InvoiceItemList)
+						//	{
+						//		typAlt = ii.ItemDescription;
+						//	}
+						//}
+
+						//if (typAlt == typNeu)
+						//{
+						//	exist = true;
+						//}
+
+						checkResult.VorhandeneRechungen.Add(siDCAlt);
+					}
+                }  
+            }
+            return result;
+        }
+
+        public virtual List<long> UpdateServiceInvoices(List<ServiceInvoiceDC> invoices)
 		{
 			//if (!Data.Security.UserRightHelper.LoggedInUserHasRight(UserRightType.AccountingTransactionView_Create))
 			//{
@@ -79,9 +240,6 @@ namespace BeWo.Service.Plugins
 				{
 					ErstelleStornoAllgemeineRechnung(item);
 				}
-
-
-
 			}
 		}
 
@@ -200,6 +358,7 @@ namespace BeWo.Service.Plugins
 	            CopyServiceInvoicePeriod(sip, copySip);
 	        }
         }
+
 		//private void CopySettlementInvoice(SettlementInvoice existingInvoice, SettlementInvoice copyInvoice)
 	 //   {
 	         
@@ -280,7 +439,53 @@ namespace BeWo.Service.Plugins
             
         }
 
-	    private Contact CreateCopyContact(Contact existingContact)
+		public void CopyInvoiceBaseDC(InvoiceBaseDC orgRechnung, ServiceInvoiceDC diffRechnung)
+		{
+			diffRechnung.InvoiceBase.DiffErstellen = true;
+			diffRechnung.InvoiceBase.AccountingPeriodStart = orgRechnung.AccountingPeriodStart;
+			diffRechnung.InvoiceBase.AccountingPeriodEnd = orgRechnung.AccountingPeriodEnd;
+			diffRechnung.InvoiceBase.CustomerLastName = orgRechnung.CustomerLastName;
+			diffRechnung.InvoiceBase.CustomerFirstName = orgRechnung.CustomerFirstName;
+			diffRechnung.InvoiceBase.CustomerReferenceNumber = orgRechnung.CustomerReferenceNumber;
+			diffRechnung.InvoiceBase.InvoiceBaseOid = orgRechnung.InvoiceBaseOid;
+			diffRechnung.InvoiceBase.InvoiceDate = orgRechnung.InvoiceDate;
+			diffRechnung.InvoiceBase.InvoiceId = orgRechnung.InvoiceId;
+			diffRechnung.InvoiceBase.InvoiceNumber = orgRechnung.InvoiceNumber;
+			diffRechnung.InvoiceBase.InvoiceTitle = orgRechnung.InvoiceTitle;
+			diffRechnung.InvoiceBase.InvoiceTypeText = orgRechnung.InvoiceTypeText;
+			diffRechnung.InvoiceBase.RecipientAddressLine1 = orgRechnung.RecipientAddressLine1;
+			diffRechnung.InvoiceBase.RecipientAddressOid = orgRechnung.RecipientAddressOid;
+			diffRechnung.InvoiceBase.RecipientAddressVersion = orgRechnung.RecipientAddressVersion;
+			diffRechnung.InvoiceBase.RecipientContactInformations = orgRechnung.RecipientContactInformations;
+			diffRechnung.InvoiceBase.RecipientCostBearerOid = orgRechnung.RecipientCostBearerOid;
+			diffRechnung.InvoiceBase.RecipientCustomerOid = orgRechnung.RecipientCustomerOid;
+			diffRechnung.InvoiceBase.RecipientDivision = orgRechnung.RecipientDivision;
+			diffRechnung.InvoiceBase.RecipientOrganisation = orgRechnung.RecipientOrganisation;
+			diffRechnung.InvoiceBase.RecipientOrganisationOid = orgRechnung.RecipientOrganisationOid;
+			diffRechnung.InvoiceBase.RecipientPersonFirstName = orgRechnung.RecipientPersonFirstName;
+			diffRechnung.InvoiceBase.RecipientPersonLastName = orgRechnung.RecipientPersonLastName;
+			diffRechnung.InvoiceBase.RecipientPersonOid = orgRechnung.RecipientPersonOid;
+			diffRechnung.InvoiceBase.RecipientPostCode = orgRechnung.RecipientPostCode;
+			diffRechnung.InvoiceBase.RecipientSalutationAddressField = orgRechnung.RecipientSalutationAddressField;
+			diffRechnung.InvoiceBase.RecipientStreet = orgRechnung.RecipientStreet;
+			diffRechnung.InvoiceBase.RecipientTown = orgRechnung.RecipientTown;
+			diffRechnung.InvoiceBase.SenderAddressOid = orgRechnung.SenderAddressOid;
+			diffRechnung.InvoiceBase.SenderAddressVersion = orgRechnung.SenderAddressVersion;
+			diffRechnung.InvoiceBase.SenderContactInformations = orgRechnung.SenderContactInformations;
+			diffRechnung.InvoiceBase.SenderDivision = orgRechnung.SenderDivision;
+			diffRechnung.InvoiceBase.SenderFirstName = orgRechnung.SenderFirstName;
+			diffRechnung.InvoiceBase.SenderLastName = orgRechnung.SenderLastName;
+			diffRechnung.InvoiceBase.SenderOrganisation = orgRechnung.SenderOrganisation;
+			diffRechnung.InvoiceBase.SenderPostCode = orgRechnung.SenderPostCode;
+			diffRechnung.InvoiceBase.SenderStreet = orgRechnung.SenderStreet;
+			diffRechnung.InvoiceBase.SenderTown = orgRechnung.SenderTown;
+			diffRechnung.InvoiceBase.SupportConceptCostBearerRelDc = orgRechnung.SupportConceptCostBearerRelDc;
+			diffRechnung.InvoiceBase.SupportConceptOid = orgRechnung.SupportConceptOid;
+			diffRechnung.InvoiceBase.TotalAmount = orgRechnung.TotalAmount;
+			diffRechnung.InvoiceBase.Type = orgRechnung.Type;
+		}
+
+		private Contact CreateCopyContact(Contact existingContact)
 	    {
 	        Contact newContact = new Contact();
 	        newContact.Value = existingContact.Value;
@@ -317,7 +522,6 @@ namespace BeWo.Service.Plugins
 	        copySip.ServiceUnitName = existingSip.ServiceUnitName;
 	        copySip.Start = existingSip.Start;
 	        copySip.Notice = existingSip.Notice;
-
             copySip.Customer = existingSip.Customer;
             copySip.SupportConceptApprovalPeriod = existingSip.SupportConceptApprovalPeriod;
 
@@ -350,8 +554,13 @@ namespace BeWo.Service.Plugins
 	        copyItem.UnitCount = existingItem.UnitCount;
 	        copyItem.UnitDescription = existingItem.UnitDescription;
 	        copyItem.Notice = existingItem.Notice;
-
             copyItem.ServiceRecord = existingItem.ServiceRecord;
         }
 	}
+
+	public class DifferenzRechnungCheck
+    {
+        public ServiceInvoiceDC NeueRechnung { get; set; }
+        public IList<ServiceInvoiceDC> VorhandeneRechungen { get; set; }
+    }
 }
\ No newline at end of file
diff --git a/Service/ServiceImplementations/AccountingServiceImp.cs b/Service/ServiceImplementations/AccountingServiceImp.cs
index 34854eefc..09f23dbf4 100644
--- a/Service/ServiceImplementations/AccountingServiceImp.cs
+++ b/Service/ServiceImplementations/AccountingServiceImp.cs
@@ -87,60 +87,9 @@ namespace BeWo.Service.ServiceImplementations
         {
             try
             {
-                var operationService = new OperationsServiceImp();
+                var acc = PluginLoader.FindClass<AccountingService>();
+                return acc.GenerateInitialServiceInvoices(costBearerOid, supportConceptOid, invoicePeriod);
 
-				IEnumerable<CompactSupportConceptDC> supportConcepts;
-                // GetAllActiveSupportConceptCostbearer returns a "Flat" SupportConcept List, one for each CostBearer2SupportConcept!
-				if (!supportConceptOid.HasValue)
-				{
-					supportConcepts = operationService.GetAllActiveSupportConceptCostbearer(false, true, 0)
-						.Where(i => i.CostBearerOids2CostBearerRelOids.ContainsKey(costBearerOid));
-				}
-				else
-				{
-					supportConcepts = operationService.GetCompactSupportConcepts(supportConceptOid.Value, null)
-						.Where(i => i.CostBearerOids2CostBearerRelOids.ContainsKey(costBearerOid));
-				}
-
-				DateTimeSpan newSpan = null;
-				if (invoicePeriod != null)
-				{
-					//invoicePeriod.StartDateTime = invoicePeriod.StartDateTime.Date;
-					//invoicePeriod.EndDateTime = invoicePeriod.EndDateTime.Date;
-					newSpan = new DateTimeSpan();
-					newSpan.StartDateTime = invoicePeriod.StartDateTime.Date;
-					newSpan.EndDateTime = invoicePeriod.EndDateTime.Date.AddDays(1).AddTicks(-1);
-					if (!supportConceptOid.HasValue)
-					{
-						supportConcepts =
-							supportConcepts.Where(sc => sc.StartDate < newSpan.EndDate && sc.EndDate >= newSpan.StartDate);
-					}
-				}
-				var supportConcepts2ServiceRecords = supportConcepts.ToDictionary(
-                                                                                      i => i,
-                                                                                      i => MapperFactory.ServiceRecordDC_ServiceRecord.MapToNewDCs(
-                                                                                                                                                   DAOFactory.SearchDAO.FindServiceRecordsInSpan(i.CostBearerRelOids[0], newSpan)));
-				var cb = DAOFactory.GenericDAO.LoadByID<CostBearer>(costBearerOid);
-				String tenant = null;
-
-				if (MultitenancyOperationContextExt.Current != null)
-					tenant = MultitenancyOperationContextExt.Current.Tenant;
-
-				var factory = PluginLoader.FindClass<InvoiceFactory>(cb.ID);
-
-	            if (factory == null)
-	            {
-		            factory = InvoiceFactory.GetInstance(cb.ID, tenant);
-	            }
-
-	            var creator = factory.CreateInvoiceCreator(cb.ID, tenant, supportConcepts2ServiceRecords);
-
-				//String text = String.Format("Tenant={0}, Context=Null? {1}, Factory = {2}", tenant,
-				//	MultitenancyOperationContextExt.Current == null, factory);
-
-				//Utils.SendErrorMail("CB DEBUG", text);
-
-                return creator.GenerateServiceInvoices(costBearerOid, invoicePeriod, supportConcepts2ServiceRecords);
             }
             catch (Exception e)
             {
@@ -434,7 +383,25 @@ namespace BeWo.Service.ServiceImplementations
         {
             try
             {
-                var newInvoices = MapperFactory.ServiceInvoiceDC_ServiceInvoice.MapToNewEntities(invoices);
+                //Prüfe Flags
+                var neueRechnungen = new List<ServiceInvoiceDC>();
+                var diffRechnungen = invoices.Where(i => i.InvoiceBase.DiffErstellen).ToList();
+
+                //Bei neuer Rechung prüfen, ob eine Diff Rechnung vorher generiert wurde.
+                foreach (var item in invoices.Where(i => i.InvoiceBase.NeuErstellen))
+                {
+                    if (item.OriginalZurDifferenz != null)
+                    {
+                        neueRechnungen.Add(item.OriginalZurDifferenz);
+                    }
+                    else
+                    {
+                        neueRechnungen.Add(item);
+                    }
+                }
+
+                var newInvoices = MapperFactory.ServiceInvoiceDC_ServiceInvoice.MapToNewEntities(neueRechnungen);
+                newInvoices.AddRange(MapperFactory.ServiceInvoiceDC_ServiceInvoice.MapToNewEntities(diffRechnungen));
 	            if (newInvoices.Count > 0)
 	            {
 		            int count = 0;
diff --git a/Shared/DataContracts/InvoiceBaseDC.cs b/Shared/DataContracts/InvoiceBaseDC.cs
index 59d1260ec..e78443c0c 100644
--- a/Shared/DataContracts/InvoiceBaseDC.cs
+++ b/Shared/DataContracts/InvoiceBaseDC.cs
@@ -61,10 +61,22 @@ namespace BS.Shared.DataContracts
         [DataMember]
         public bool IsPaid { get; set; }
 
+        [DataMember]
+        public bool NeuErstellen { get; set; }
+
+        [DataMember]
+        public bool DiffErstellen { get; set; }
+
         [DataMember]
         public string Notice { get; set; }
 
-		[DataMember]
+        [DataMember]
+        public string Details { get; set; }
+
+        [DataMember]
+        public string Hinweise { get; set; }
+
+        [DataMember]
 		public string InvoiceId { get; set; }
 
 		[DataMember]
diff --git a/Shared/DataContracts/ServiceInvoiceDC.cs b/Shared/DataContracts/ServiceInvoiceDC.cs
index 96d609a62..768fffb77 100644
--- a/Shared/DataContracts/ServiceInvoiceDC.cs
+++ b/Shared/DataContracts/ServiceInvoiceDC.cs
@@ -77,6 +77,9 @@ namespace BS.Shared.DataContracts
         [DataMember]
         public CostRatePeriodDC ServiceUnit { get; set; }
 
+        [DataMember]
+        public ServiceInvoiceDC OriginalZurDifferenz { get; set; }
+
         public decimal? ClaimSum
         {
             get { return ServiceInvoicePeriods.Sum(i => i.Claim); }