diff --git a/IMPROVEMENT_PLAN.md b/IMPROVEMENT_PLAN.md
index da19b31..ab9f5ae 100644
--- a/IMPROVEMENT_PLAN.md
+++ b/IMPROVEMENT_PLAN.md
@@ -97,6 +97,7 @@ Analysis and phased plan produced 2026-07-02. See conversation history for full
 
 - **PR A** — Phase 1 items 1–7 + CLAUDE.md fix.
 - **PR B** — Phase 1 item 8 (atomic writes + lock).
-- **PR C** — Phase 2 items 9 + 11 + 13 + 15 + 16 + 17.
-- **PR D** — Phase 3 (async).
-- **PR E** — Phase 4 (tests) — done alongside PR C to lock in behavior.
+- **PR C** — Phase 2 mechanical cleanup: items 11, 13, 15, 16, 17.
+- **PR D** — Phase 2 item 9: per-request unit of work / cache. Split off from PR C because it is invasive enough to warrant its own review.
+- **PR E** — Phase 3 (async).
+- **PR F** — Phase 4 (tests) — done alongside PR D to lock in behavior.
diff --git a/Schaad.Accounting.Common/Formatting.cs b/Schaad.Accounting.Common/Formatting.cs
new file mode 100644
index 0000000..58536d1
--- /dev/null
+++ b/Schaad.Accounting.Common/Formatting.cs
@@ -0,0 +1,19 @@
+using System.Globalization;
+
+namespace Schaad.Accounting
+{
+    public static class Formatting
+    {
+        private static readonly CultureInfo SwissCulture = CreateSwissCulture();
+
+        public static string ToFormattedString(this decimal value)
+            => value.ToString("#,0.00", SwissCulture);
+
+        private static CultureInfo CreateSwissCulture()
+        {
+            var culture = new CultureInfo("de-CH");
+            culture.NumberFormat.NumberGroupSeparator = "'";
+            return culture;
+        }
+    }
+}
diff --git a/Schaad.Accounting.Common/Interfaces/ISplitPredefinitonRepository.cs b/Schaad.Accounting.Common/Interfaces/ISplitPredefinitionRepository.cs
similarity index 71%
rename from Schaad.Accounting.Common/Interfaces/ISplitPredefinitonRepository.cs
rename to Schaad.Accounting.Common/Interfaces/ISplitPredefinitionRepository.cs
index d635881..151ec8e 100644
--- a/Schaad.Accounting.Common/Interfaces/ISplitPredefinitonRepository.cs
+++ b/Schaad.Accounting.Common/Interfaces/ISplitPredefinitionRepository.cs
@@ -1,12 +1,12 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using Schaad.Accounting.Models;
 
 namespace Schaad.Accounting.Interfaces
 {
-    public interface ISplitPredefinitonRepository
+    public interface ISplitPredefinitionRepository
     {
         List<SplitPredefinition> GetSplitPredefinitionList();
 
         void SaveSplitPredefinition(SplitPredefinition splitPredefinition);
     }
-}
\ No newline at end of file
+}
diff --git a/Schaad.Accounting.Common/Schaad.Accounting.Common.csproj b/Schaad.Accounting.Common/Schaad.Accounting.Common.csproj
index 47844fe..20fe4e1 100644
--- a/Schaad.Accounting.Common/Schaad.Accounting.Common.csproj
+++ b/Schaad.Accounting.Common/Schaad.Accounting.Common.csproj
@@ -4,17 +4,9 @@
     <TargetFramework>net9.0</TargetFramework>
     <RootNamespace>Schaad.Accounting</RootNamespace>
   </PropertyGroup>
-  <ItemGroup>
-    <PackageReference Include="System.Text.RegularExpressions" Version="4.3.1" />
-    <PackageReference Include="System.Xml.XmlSerializer" Version="4.3.0" />
-    <PackageReference Include="System.ComponentModel.Annotations" Version="5.0.0" />
-  </ItemGroup>
   <ItemGroup>
     <Reference Include="Schaad.Finance.Api">
       <HintPath>..\dlls\Schaad.Finance.Api.dll</HintPath>
     </Reference>
   </ItemGroup>
-  <ItemGroup>
-    <Folder Include="Interfaces\Extensions\" />
-  </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/Schaad.Accounting.Db/Repositories/AccountRepository.cs b/Schaad.Accounting.Db/Repositories/AccountRepository.cs
index d96683e..1061dc9 100644
--- a/Schaad.Accounting.Db/Repositories/AccountRepository.cs
+++ b/Schaad.Accounting.Db/Repositories/AccountRepository.cs
@@ -13,7 +13,7 @@ namespace Schaad.Accounting.Repositories
 
         public AccountRepository(ISettingsService settingsService) : base(settingsService)
         {
-            EnsureFileExisits(ACCOUNTS);
+            EnsureAccountsFile();
         }
 
 
@@ -79,35 +79,40 @@ namespace Schaad.Accounting.Repositories
             SaveAccount(account);
         }
 
-        private new void EnsureFileExisits(string file)
+        private void EnsureAccountsFile()
         {
-            string filePath = Path.Combine(settingsService.GetDbPath(), file);
-            if (File.Exists(filePath) == false)
+            string filePath = Path.Combine(settingsService.GetDbPath(), ACCOUNTS);
+            if (File.Exists(filePath))
             {
-                var lastYearFile = Path.Combine(settingsService.GetLastYearDbPath(), file);
-                if (File.Exists(lastYearFile))
-                    File.Copy(lastYearFile, filePath);
+                return;
+            }
 
-                // set start balance to last bank balance
-                if (file.IndexOf("Accounts") > -1)
+            var lastYearFile = Path.Combine(settingsService.GetLastYearDbPath(), ACCOUNTS);
+            if (File.Exists(lastYearFile))
+            {
+                File.Copy(lastYearFile, filePath);
+            }
+
+            // Year rollover: seed start balances from the previous year's closing values.
+            // Bank accounts start at the last known bank balance; cash accounts start at zero.
+            var accounts = GetAccountList();
+            var modified = false;
+            foreach (var account in accounts.Where(a => a.Class == ClassIds.Activa))
+            {
+                if (account.LastBankBalance > 0)
                 {
-                    var accounts = GetAccountList();
-                    foreach (var account in accounts.Where(a => a.Class == ClassIds.Activa))
-                    {
-                        // bank accounts
-                        if (account.LastBankBalance > 0)
-                        {
-                            account.StartBalance = account.LastBankBalance;
-                            SaveAccount(account);
-                        }
-                        // cash accounts
-                        else if (account.Number < 1010)
-                        {
-                            account.StartBalance = 0;
-                            SaveAccount(account);
-                        }
-                    }
+                    account.StartBalance = account.LastBankBalance;
+                    modified = true;
                 }
+                else if (account.Number < 1010)
+                {
+                    account.StartBalance = 0;
+                    modified = true;
+                }
+            }
+            if (modified)
+            {
+                Save(accounts, ACCOUNTS);
             }
         }
     }
diff --git a/Schaad.Accounting.Db/Repositories/BaseRepository.cs b/Schaad.Accounting.Db/Repositories/BaseRepository.cs
index 9f727d8..4411e15 100644
--- a/Schaad.Accounting.Db/Repositories/BaseRepository.cs
+++ b/Schaad.Accounting.Db/Repositories/BaseRepository.cs
@@ -22,7 +22,7 @@ namespace Schaad.Accounting.Repositories
             this.settingsService = settingsService;
         }
 
-        protected void EnsureFileExisits(string fileName)
+        protected void EnsureFileExists(string fileName)
         {
             string filePath = Path.Combine(settingsService.GetDbPath(), fileName);
             lock (GetLock(filePath))
diff --git a/Schaad.Accounting.Db/Repositories/BookingRuleRepository.cs b/Schaad.Accounting.Db/Repositories/BookingRuleRepository.cs
index 3e3fd81..619fce4 100644
--- a/Schaad.Accounting.Db/Repositories/BookingRuleRepository.cs
+++ b/Schaad.Accounting.Db/Repositories/BookingRuleRepository.cs
@@ -12,7 +12,7 @@ namespace Schaad.Accounting.Repositories
 
         public BookingRuleRepository(ISettingsService settingsService) : base(settingsService)
         {
-            EnsureFileExisits(BOOKING_RULES);
+            EnsureFileExists(BOOKING_RULES);
         }
 
         /// <summary>
diff --git a/Schaad.Accounting.Db/Repositories/BookingTextRepository.cs b/Schaad.Accounting.Db/Repositories/BookingTextRepository.cs
index 2844db3..d3fa0c7 100644
--- a/Schaad.Accounting.Db/Repositories/BookingTextRepository.cs
+++ b/Schaad.Accounting.Db/Repositories/BookingTextRepository.cs
@@ -12,7 +12,7 @@ namespace Schaad.Accounting.Repositories
 
         public BookingTextRepository(ISettingsService settingsService) : base(settingsService)
         {
-            EnsureFileExisits(BOOKING_TEXTS);
+            EnsureFileExists(BOOKING_TEXTS);
         }
 
         /// <summary>
diff --git a/Schaad.Accounting.Db/Repositories/SplitPredefinitonRepository.cs b/Schaad.Accounting.Db/Repositories/SplitPredefinitionRepository.cs
similarity index 77%
rename from Schaad.Accounting.Db/Repositories/SplitPredefinitonRepository.cs
rename to Schaad.Accounting.Db/Repositories/SplitPredefinitionRepository.cs
index 47c716e..ac80d29 100644
--- a/Schaad.Accounting.Db/Repositories/SplitPredefinitonRepository.cs
+++ b/Schaad.Accounting.Db/Repositories/SplitPredefinitionRepository.cs
@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using Schaad.Accounting.Interfaces;
@@ -6,17 +6,17 @@ using Schaad.Accounting.Models;
 
 namespace Schaad.Accounting.Repositories
 {
-    public class SplitPredefinitonRepository : BaseRepository, ISplitPredefinitonRepository
+    public class SplitPredefinitionRepository : BaseRepository, ISplitPredefinitionRepository
     {
         private readonly string SPLIT_PREDEFINITION = "SplitPredefinitions.xml";
 
-        public SplitPredefinitonRepository(ISettingsService settingsService) : base(settingsService)
+        public SplitPredefinitionRepository(ISettingsService settingsService) : base(settingsService)
         {
-            EnsureFileExisits(SPLIT_PREDEFINITION);
+            EnsureFileExists(SPLIT_PREDEFINITION);
         }
 
         /// <summary>
-        /// Load booking rules
+        /// Load split predefinitions
         /// </summary>
         public List<SplitPredefinition> GetSplitPredefinitionList()
         {
@@ -25,7 +25,7 @@ namespace Schaad.Accounting.Repositories
         }
 
         /// <summary>
-        /// Save a booking rule (insert/update)
+        /// Save a split predefinition (insert/update)
         /// </summary>
         public void SaveSplitPredefinition(SplitPredefinition splitPredefinition)
         {
@@ -42,4 +42,4 @@ namespace Schaad.Accounting.Repositories
             Save(definitions, SPLIT_PREDEFINITION);
         }
     }
-}
\ No newline at end of file
+}
diff --git a/Schaad.Accounting.Db/Repositories/SubclassRepository.cs b/Schaad.Accounting.Db/Repositories/SubclassRepository.cs
index 55762fb..f2ecb7c 100644
--- a/Schaad.Accounting.Db/Repositories/SubclassRepository.cs
+++ b/Schaad.Accounting.Db/Repositories/SubclassRepository.cs
@@ -13,7 +13,7 @@ namespace Schaad.Accounting.Repositories
 
         public SubclassRepository(ISettingsService settingsService) : base(settingsService)
         {
-            EnsureFileExisits(SUBCLASSES);
+            EnsureFileExists(SUBCLASSES);
 
             classes.Add(ClassIds.Activa, "Aktiven");
             classes.Add(ClassIds.Passiva, "Passiven");
diff --git a/Schaad.Accounting.Db/Schaad.Accounting.Db.csproj b/Schaad.Accounting.Db/Schaad.Accounting.Db.csproj
index bed63a7..8f28362 100644
--- a/Schaad.Accounting.Db/Schaad.Accounting.Db.csproj
+++ b/Schaad.Accounting.Db/Schaad.Accounting.Db.csproj
@@ -4,9 +4,6 @@
     <TargetFramework>net9.0</TargetFramework>
   </PropertyGroup>
 
-  <ItemGroup>
-    <PackageReference Include="System.Text.RegularExpressions" Version="4.3.1" />
-  </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Schaad.Accounting.Common\Schaad.Accounting.Common.csproj" />
   </ItemGroup>
diff --git a/Schaad.Accounting.Services/FileService.cs b/Schaad.Accounting.Services/FileService.cs
index 57f24b4..e6b3b8f 100644
--- a/Schaad.Accounting.Services/FileService.cs
+++ b/Schaad.Accounting.Services/FileService.cs
@@ -1,5 +1,4 @@
 using System.Collections.Generic;
-using System.Globalization;
 using System.IO.Compression;
 using System.Linq;
 using System.Text;
@@ -134,25 +133,18 @@ namespace Schaad.Accounting.Services
 
                 if (trx.OriginAccountId == accountId)
                 {
-                    debit = ToFormattedString(trx.Value);
+                    debit = trx.Value.ToFormattedString();
                     signedValue = -trx.Value;
                 }
                 else
                 {
-                    credit = ToFormattedString(trx.Value);
+                    credit = trx.Value.ToFormattedString();
                 }
                 balance += signedValue;
-                sb.AppendLine($"{trx.BookingDate:dd.MM.yyyy};{trx.ValueDate:dd.MM.yyyy};{trx.Text};{debit};{credit};{ToFormattedString(balance)}");
+                sb.AppendLine($"{trx.BookingDate:dd.MM.yyyy};{trx.ValueDate:dd.MM.yyyy};{trx.Text};{debit};{credit};{balance.ToFormattedString()}");
             }
             var fileBytes = Encoding.GetEncoding("ISO-8859-1").GetBytes(sb.ToString());
             return fileBytes;
         }
-        
-        private string ToFormattedString(decimal value)
-        {
-            var culture = new CultureInfo("de-CH");
-            culture.NumberFormat.NumberGroupSeparator = "'";
-            return value.ToString("#,0.00", culture);
-        }
     }
 }
\ No newline at end of file
diff --git a/Schaad.Accounting.Services/Schaad.Accounting.Services.csproj b/Schaad.Accounting.Services/Schaad.Accounting.Services.csproj
index 8bc3a30..2def6e6 100644
--- a/Schaad.Accounting.Services/Schaad.Accounting.Services.csproj
+++ b/Schaad.Accounting.Services/Schaad.Accounting.Services.csproj
@@ -6,7 +6,6 @@
 
   <ItemGroup>
     <PackageReference Include="FreeSpire.PDF" Version="10.2.0" />
-    <PackageReference Include="System.Text.RegularExpressions" Version="4.3.1" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="..\Schaad.Accounting.Common\Schaad.Accounting.Common.csproj" />
diff --git a/Schaad.Accounting.UI/Extensions.cs b/Schaad.Accounting.UI/Extensions.cs
index 22f714d..b564a45 100644
--- a/Schaad.Accounting.UI/Extensions.cs
+++ b/Schaad.Accounting.UI/Extensions.cs
@@ -1,5 +1,4 @@
-using System.Globalization;
-using Schaad.Accounting.Interfaces;
+using Schaad.Accounting.Interfaces;
 using Schaad.Accounting.Repositories;
 using Schaad.Accounting.Services;
 using Schaad.Finance.Api;
@@ -9,13 +8,6 @@ namespace Schaad.Accounting.UI
 {
     public static class Extensions
     {
-        public static string ToFormattedString(this decimal value)
-        {
-            var culture = new CultureInfo("de-CH");
-            culture.NumberFormat.NumberGroupSeparator = "'";
-            return value.ToString("#,0.00", culture);
-        }
-        
         public static IServiceCollection AddAccounting(this IServiceCollection services)
         {
             // Singleton because MyHeader triggers a full page reload (forceLoad: true) after
@@ -28,7 +20,7 @@ namespace Schaad.Accounting.UI
             services.AddScoped<IBankTransactionRepository, BankTransactionRepository>();
             services.AddScoped<IBookingRuleRepository, BookingRuleRepository>();
             services.AddScoped<IBookingTextRepository, BookingTextRepository>();
-            services.AddScoped<ISplitPredefinitonRepository, SplitPredefinitonRepository>();
+            services.AddScoped<ISplitPredefinitionRepository, SplitPredefinitionRepository>();
             services.AddScoped<ISubclassRepository, SubclassRepository>();
             services.AddScoped<ITransactionRepository, TransactionRepository>();
 
diff --git a/Schaad.Accounting.UI/Program.cs b/Schaad.Accounting.UI/Program.cs
index e570cc7..5475d30 100644
--- a/Schaad.Accounting.UI/Program.cs
+++ b/Schaad.Accounting.UI/Program.cs
@@ -1,4 +1,5 @@
 using System.Globalization;
+using Microsoft.AspNetCore.Localization;
 using Microsoft.Extensions.Options;
 using Microsoft.FluentUI.AspNetCore.Components;
 using Schaad.Accounting.Datasets;
@@ -38,15 +39,19 @@ namespace Schaad.Accounting.UI
 
             app.UseHttpsRedirection();
 
+            var supportedCultures = new[] { new CultureInfo("de-CH") };
+            app.UseRequestLocalization(new RequestLocalizationOptions
+            {
+                DefaultRequestCulture = new RequestCulture(supportedCultures[0]),
+                SupportedCultures = supportedCultures,
+                SupportedUICultures = supportedCultures
+            });
+
             app.UseAntiforgery();
             app.MapStaticAssets();
             app.MapRazorComponents<App>()
                 .AddInteractiveServerRenderMode();
-            
-            var culture = new CultureInfo("de-CH");
-            CultureInfo.DefaultThreadCurrentCulture = culture;
-            CultureInfo.DefaultThreadCurrentUICulture = culture;
-            
+
             app.Run();
         }
     }