diff --git a/BeWo/DebugConfig.cs b/BeWo/DebugConfig.cs
index c7dde3a75..134fbe7fe 100644
--- a/BeWo/DebugConfig.cs
+++ b/BeWo/DebugConfig.cs
@@ -24,7 +24,7 @@ namespace BeWo
             {
                 #if DEBUG
 
-                return _CurrentConfig ?? (_CurrentConfig = SimpleAutoLogin);
+                return _CurrentConfig ?? (_CurrentConfig = Feature_Dakota);
 
                 #endif
 
diff --git a/BeWo/ServiceProxy/Generated.cs b/BeWo/ServiceProxy/Generated.cs
index 82b7f3448..b01b4c42a 100644
--- a/BeWo/ServiceProxy/Generated.cs
+++ b/BeWo/ServiceProxy/Generated.cs
@@ -9596,6 +9596,12 @@ namespace BeWo.ServiceProxy
             "ault", Name="BeWoFault", Namespace="http://schemas.datacontract.org/2004/07/BeWo.Service.ServiceContracts")]
         System.Collections.Generic.List<BS.Shared.DataContracts.InvoiceBaseDC> GetInvoiceBasesForCostBearerAndId(System.Nullable<System.DateTime> startDate, System.Nullable<System.DateTime> endDate, long costBearerOid, string invoiceId);
         
+        [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/IAccountingService/GetInvoiceBasesForCostBearerAndIdAndIsUsed", ReplyAction="http://tempuri.org/IAccountingService/GetInvoiceBasesForCostBearerAndIdAndIsUsedR" +
+            "esponse")]
+        [System.ServiceModel.FaultContractAttribute(typeof(BeWo.ServiceProxy.BeWoFault), Action="http://tempuri.org/IAccountingService/GetInvoiceBasesForCostBearerAndIdAndIsUsedB" +
+            "eWoFaultFault", Name="BeWoFault", Namespace="http://schemas.datacontract.org/2004/07/BeWo.Service.ServiceContracts")]
+        System.Collections.Generic.List<BS.Shared.DataContracts.InvoiceBaseDC> GetInvoiceBasesForCostBearerAndIdAndIsUsed(System.Nullable<System.DateTime> startDate, System.Nullable<System.DateTime> endDate, long costBearerOid, string invoiceId);
+        
         [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/IAccountingService/GetGeneralInvoiceBasesForCustomer", ReplyAction="http://tempuri.org/IAccountingService/GetGeneralInvoiceBasesForCustomerResponse")]
         [System.ServiceModel.FaultContractAttribute(typeof(BeWo.ServiceProxy.BeWoFault), Action="http://tempuri.org/IAccountingService/GetGeneralInvoiceBasesForCustomerBeWoFaultF" +
             "ault", Name="BeWoFault", Namespace="http://schemas.datacontract.org/2004/07/BeWo.Service.ServiceContracts")]
@@ -9807,6 +9813,11 @@ namespace BeWo.ServiceProxy
             return base.Channel.GetInvoiceBasesForCostBearerAndId(startDate, endDate, costBearerOid, invoiceId);
         }
         
+        public System.Collections.Generic.List<BS.Shared.DataContracts.InvoiceBaseDC> GetInvoiceBasesForCostBearerAndIdAndIsUsed(System.Nullable<System.DateTime> startDate, System.Nullable<System.DateTime> endDate, long costBearerOid, string invoiceId)
+        {
+            return base.Channel.GetInvoiceBasesForCostBearerAndIdAndIsUsed(startDate, endDate, costBearerOid, invoiceId);
+        }
+        
         public System.Collections.Generic.List<BS.Shared.DataContracts.InvoiceBaseDC> GetGeneralInvoiceBasesForCustomer(long customerOid)
         {
             return base.Channel.GetGeneralInvoiceBasesForCustomer(customerOid);
diff --git a/BeWo/Styles/ModernOrangeBlack.xaml b/BeWo/Styles/ModernOrangeBlack.xaml
index 357934f1f..72279e02c 100644
--- a/BeWo/Styles/ModernOrangeBlack.xaml
+++ b/BeWo/Styles/ModernOrangeBlack.xaml
@@ -40,5 +40,4 @@
     <Style BasedOn="{StaticResource BaseRadioButton}" TargetType="RadioButton" />
     <Style BasedOn="{StaticResource TextBoxBase}" TargetType="TextBox" />
     <Style BasedOn="{StaticResource BaseTextEdit}" TargetType="dxe:TextEdit" />
-
 </ResourceDictionary>
\ No newline at end of file
diff --git a/BeWo/View/Detail/Accounting/GkvAbrechnungOverview.xaml.cs b/BeWo/View/Detail/Accounting/GkvAbrechnungOverview.xaml.cs
index 16a0f505b..8a78e94b6 100644
--- a/BeWo/View/Detail/Accounting/GkvAbrechnungOverview.xaml.cs
+++ b/BeWo/View/Detail/Accounting/GkvAbrechnungOverview.xaml.cs
@@ -123,11 +123,9 @@ namespace BeWo.View.Detail.Accounting
         {
             var checked_invoice_bases = _NewGkvAbrechnungPopUpView.ViewModel.InvoiceBases.Where(x => x.IsChecked).Select(x => x.DataContract.InvoiceBaseOid.Value).ToList();
 
+            // MessageBox.Show("Sie haben keine Rechnung hinzugefügt.", "GKV-Abrechnung erstellen", MessageBoxButton.OK, MessageBoxImage.Warning);
             if (checked_invoice_bases.Count == 0)
-            {
-                MessageBox.Show("Sie haben keine Rechnung hinzugefügt.", "GKV-Abrechnung erstellen", MessageBoxButton.OK, MessageBoxImage.Warning);
                 return;
-            }
 
             MainControl.CloseCurrentPopUp();
 
diff --git a/BeWo/View/Master/FinanceView.xaml b/BeWo/View/Master/FinanceView.xaml
index 027211665..d8f9addef 100644
--- a/BeWo/View/Master/FinanceView.xaml
+++ b/BeWo/View/Master/FinanceView.xaml
@@ -15,7 +15,8 @@
     HorizontalAlignment="Stretch"
     VerticalAlignment="Stretch"
     Focusable="True"
-    Loaded="BeWoView_Loaded">
+    Loaded="BeWoView_Loaded"
+    Unloaded="BeWoView_Unloaded">
 
     <Grid>
         <uc:ShadowChrome>
diff --git a/BeWo/View/Master/FinanceView.xaml.cs b/BeWo/View/Master/FinanceView.xaml.cs
index e27a797e4..d75199988 100644
--- a/BeWo/View/Master/FinanceView.xaml.cs
+++ b/BeWo/View/Master/FinanceView.xaml.cs
@@ -67,16 +67,16 @@ namespace BeWo.View.Master
         {
             var lDoSave = true;
 
-            if (root.SelectedItem != null)
+            if (root.SelectedItem is TabItem selected)
             {
-                if (_OpenViews.ContainsKey(root.SelectedItem as TabItem))
+                if (_OpenViews.ContainsKey(selected))
                 {
-                    lDoSave = _OpenViews[root.SelectedItem as TabItem].DoSaveCheck();
+                    lDoSave = _OpenViews[selected].DoSaveCheck();
 
                     if (lDoSave && IsDirty)
                     {
                         _SavePerformed = true;
-                        _OpenViews.Remove(root.SelectedItem as TabItem);
+                        _OpenViews.Remove(selected);
                     }
                 }
             }
@@ -307,5 +307,13 @@ namespace BeWo.View.Master
 
             _AlreadyLoaded = true;
         }
+
+		private void BeWoView_Unloaded(object sender, RoutedEventArgs e)
+		{
+            if(root.SelectedItem != tabitem_gkvabrechnung)
+			{
+                RemoveView(tabitem_gkvabrechnung);
+			}
+		}
 	}
 }
\ No newline at end of file
diff --git a/Service/DCEntityMapper/GkvAbrechnungDC_GkvAbrechnung.cs b/Service/DCEntityMapper/GkvAbrechnungDC_GkvAbrechnung.cs
index 909792224..a5c6b2957 100644
--- a/Service/DCEntityMapper/GkvAbrechnungDC_GkvAbrechnung.cs
+++ b/Service/DCEntityMapper/GkvAbrechnungDC_GkvAbrechnung.cs
@@ -83,7 +83,6 @@ namespace BeWo.Service.DCEntityMapper
                     isReady = false;
                     tooltip = "Organisation fehlen Informationen";
                 }
-
             }
 
             pDataContract.IsReady2Send = isReady;
diff --git a/Service/ServiceContracts/IAccountingService.cs b/Service/ServiceContracts/IAccountingService.cs
index 238797f3d..70696383d 100644
--- a/Service/ServiceContracts/IAccountingService.cs
+++ b/Service/ServiceContracts/IAccountingService.cs
@@ -44,6 +44,10 @@ namespace BeWo.Service.ServiceContracts
         [FaultContract(typeof(BeWoFault))]
         [OperationContract]
         List<InvoiceBaseDC> GetInvoiceBasesForCostBearerAndId(DateTime? startDate, DateTime? endDate, long costBearerOid, String invoiceId);
+        
+        [FaultContract(typeof(BeWoFault))]
+        [OperationContract]
+        List<InvoiceBaseDC> GetInvoiceBasesForCostBearerAndIdAndIsUsed(DateTime? startDate, DateTime? endDate, long costBearerOid, String invoiceId);
 
         [FaultContract(typeof(BeWoFault))]
         [OperationContract]
diff --git a/Service/ServiceImplementations/AccountingServiceImp.cs b/Service/ServiceImplementations/AccountingServiceImp.cs
index 880fa8332..53acc7c2f 100644
--- a/Service/ServiceImplementations/AccountingServiceImp.cs
+++ b/Service/ServiceImplementations/AccountingServiceImp.cs
@@ -160,6 +160,38 @@ namespace BeWo.Service.ServiceImplementations
 			}
 		}
 
+		public List<InvoiceBaseDC> GetInvoiceBasesForCostBearerAndIdAndIsUsed(DateTime? startDate, DateTime? endDate, long costBearerOid, String invoiceId)
+		{
+			try
+			{
+				var gkv_abrechnungen = DAOFactory.GenericDAO.GetAllActive<GkvAbrechnung>();
+
+				var s = PluginLoader.FindClass<AccountingService>();
+
+				var rtn = s.GetInvoiceBases(startDate, endDate, costBearerOid, invoiceId);
+
+				HashSet<long> invoices = new HashSet<long>();
+				foreach (var gkv_abrechnung in gkv_abrechnungen)
+				{
+					foreach (var invoice in gkv_abrechnung.InvoiceBases)
+					{
+						invoices.Add(invoice.Oid.Value);
+					}
+				}
+
+				foreach (var invoice in rtn)
+				{
+					invoice.IsAlreadyInActiveGkvAbrechnung = invoices.Contains(invoice.InvoiceBaseOid.Value);
+				}
+
+				return rtn;
+			}
+			catch (Exception e)
+			{
+				throw Utils.CreateBeWoFaultException(e);
+			}
+		}
+
 		public List<InvoiceBaseDC> GetGeneralInvoiceBasesForCustomer(long customerOid)
 		{
 			try
diff --git a/Shared/DataContracts/InvoiceBaseDC.cs b/Shared/DataContracts/InvoiceBaseDC.cs
index 00a6b73d2..efd11551c 100644
--- a/Shared/DataContracts/InvoiceBaseDC.cs
+++ b/Shared/DataContracts/InvoiceBaseDC.cs
@@ -25,6 +25,9 @@ namespace BS.Shared.DataContracts
         [DataMember]
         public string CreatorLastName { get; set; }
 
+        [DataMember]
+        public bool IsAlreadyInActiveGkvAbrechnung { get; set; }
+
         [DataMember]
         public bool IsGkvValid { get; set; }