diff --git a/ucalc/BillingWindow.xaml.cs b/ucalc/BillingWindow.xaml.cs
index e496078..1bb0ddf 100644
--- a/ucalc/BillingWindow.xaml.cs
+++ b/ucalc/BillingWindow.xaml.cs
@@ -52,6 +52,7 @@ namespace UCalc
         private void OnTenantsFrameLoadCompleted(object sender, NavigationEventArgs e)
         {
             var page = (TenantsPage) ((Frame) sender).Content;
+            page.Model = Model;
             page.Tenants = Model.Root.Tenants;
             page.House = Model.Root.House;
             page.ParentWindow = this;
diff --git a/ucalc/Constants.cs b/ucalc/Constants.cs
index 199cbe3..db656b2 100644
--- a/ucalc/Constants.cs
+++ b/ucalc/Constants.cs
@@ -11,7 +11,7 @@ namespace UCalc
         public static readonly SolidColorBrush MainColor = Brushes.White;
         public static readonly SolidColorBrush SubMainColor = new SolidColorBrush(Color.FromRgb(0x00, 0x7A, 0xCC));
 
-        public const string DecimalFormat = ".00";
+        public const string DecimalFormat = "0.00";
         public const string DateFormat = "dd.MM.yyyy";
 
         public static readonly ImmutableList<string> SalutationStrs =
diff --git a/ucalc/Models/Model.cs b/ucalc/Models/Model.cs
index 378bdef..4175295 100644
--- a/ucalc/Models/Model.cs
+++ b/ucalc/Models/Model.cs
@@ -127,11 +127,15 @@ namespace UCalc.Models
         }
 
         private readonly Validator _validator;
+        public DateTime StartDate { get; }
+        public DateTime EndDate { get; }
         public BillingProperty Root { get; }
 
         public Model(Billing billing)
         {
             _validator = new Validator(this);
+            StartDate = billing.StartDate;
+            EndDate = billing.EndDate;
 
             using var validator = BeginValidation();
             Root = new BillingProperty(this, null, billing);
diff --git a/ucalc/Models/Properties.cs b/ucalc/Models/Properties.cs
index fbea7c5..c2e5ff3 100644
--- a/ucalc/Models/Properties.cs
+++ b/ucalc/Models/Properties.cs
@@ -1,4 +1,5 @@
-using System.Collections;
+using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
 using System.ComponentModel;
@@ -171,9 +172,17 @@ namespace UCalc.Models
 
         protected override string ValidateValue()
         {
-            return !decimal.TryParse(Value, out var n) || n < 0
-                ? $"{Name}: Der eingegebene Wert ist kein gültiger Betrag."
-                : "";
+            if (!decimal.TryParse(Value, out var n) || n < 0)
+            {
+                return $"{Name}: Der eingegebene Wert ist kein gültiger Betrag.";
+            }
+
+            if (Math.Round(n, 2) != n)
+            {
+                return $"{Name}: Der eingegebene Wert besitzt mehr als 2 Nachkommastellen.";
+            }
+
+            return "";
         }
     }
 
diff --git a/ucalc/Pages/TenantsPage.xaml.cs b/ucalc/Pages/TenantsPage.xaml.cs
index 5ccb7ad..fef3a89 100644
--- a/ucalc/Pages/TenantsPage.xaml.cs
+++ b/ucalc/Pages/TenantsPage.xaml.cs
@@ -7,6 +7,7 @@ namespace UCalc.Pages
     public partial class TenantsPage
     {
         public Window ParentWindow { get; set; }
+        public Model Model { get; set; }
         public TenantsProperty Tenants { get; set; }
         public HouseProperty House { get; set; }
 
@@ -35,7 +36,7 @@ namespace UCalc.Pages
         {
             var tenant = (TenantProperty) ((HighlightButton) sender).DataContext;
 
-            new TenantWindow(tenant, House) {Owner = ParentWindow}.ShowDialog();
+            new TenantWindow(Model, tenant, House) {Owner = ParentWindow}.ShowDialog();
         }
     }
 }
\ No newline at end of file
diff --git a/ucalc/TenantWindow.xaml b/ucalc/TenantWindow.xaml
index 55995a4..bf3c455 100644
--- a/ucalc/TenantWindow.xaml
+++ b/ucalc/TenantWindow.xaml
@@ -151,9 +151,11 @@
                                         DockPanel.Dock="Right"
                                         VerticalAlignment="Center"
                                         Property="{Binding Path=Tenant.EntryDate, RelativeSource={RelativeSource AncestorType=local:TenantWindow}}" />
-<!-- TODO                                 DisplayDateStart="{}" -->
+
                     <DatePicker VerticalAlignment="Center"
                                 MinHeight="22"
+                                DisplayDateStart="{Binding Path=Model.StartDate, RelativeSource={RelativeSource AncestorType=local:TenantWindow}, Mode=OneWay}"
+                                DisplayDateEnd="{Binding Path=Model.EndDate, RelativeSource={RelativeSource AncestorType=local:TenantWindow}, Mode=OneWay}"
                                 Text="{Binding Path=Tenant.EntryDate.Value, RelativeSource={RelativeSource AncestorType=local:TenantWindow}, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay, Converter={StaticResource DatePickerTextToDateTimeConverter}}" />
                 </DockPanel>
 
@@ -170,6 +172,8 @@
 
                     <DatePicker VerticalAlignment="Center"
                                 MinHeight="22"
+                                DisplayDateStart="{Binding Path=Model.StartDate, RelativeSource={RelativeSource AncestorType=local:TenantWindow}, Mode=OneWay}"
+                                DisplayDateEnd="{Binding Path=Model.EndDate, RelativeSource={RelativeSource AncestorType=local:TenantWindow}, Mode=OneWay}"
                                 Text="{Binding Path=Tenant.DepartureDate.Value, RelativeSource={RelativeSource AncestorType=local:TenantWindow}, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay, Converter={StaticResource DatePickerTextToDateTimeConverter}}" />
                 </DockPanel>
 
diff --git a/ucalc/TenantWindow.xaml.cs b/ucalc/TenantWindow.xaml.cs
index 151ed85..2b4c218 100644
--- a/ucalc/TenantWindow.xaml.cs
+++ b/ucalc/TenantWindow.xaml.cs
@@ -7,11 +7,13 @@ namespace UCalc
 {
     public partial class TenantWindow
     {
+        public Model Model { get; }
         public TenantProperty Tenant { get; }
         public HouseProperty House { get; }
 
-        public TenantWindow(TenantProperty tenant, HouseProperty house)
+        public TenantWindow(Model model, TenantProperty tenant, HouseProperty house)
         {
+            Model = model;
             Tenant = tenant;
             House = house;
             InitializeComponent();