diff --git a/CLAUDE.md b/CLAUDE.md
index ad8bb5f..7978d27 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -28,6 +28,8 @@ The name for the App is KOOGLE. Koogle is an app for club management.
 
 ## Implementation Plan
 
+- alle Implementierung sollen mit xmldoc in englischer Spreche kommentiert werden
+
 **Phase 1 MVP:** See [docs/IMPLEMENTATION_PLAN.md](./docs/IMPLEMENTATION_PLAN.md)
 - 23 granular phases (A1-F3)
 - Foundation → Clubs → Users → Persons → Days → Dashboard
diff --git a/docs/IMPLEMENTATION_PLAN.md b/docs/IMPLEMENTATION_PLAN.md
index f5fffa2..520c0c3 100644
--- a/docs/IMPLEMENTATION_PLAN.md
+++ b/docs/IMPLEMENTATION_PLAN.md
@@ -325,7 +325,7 @@ NavMenu.razor:
 |---|-------|---------|--------------|---------|
 | ✓ | A1 | Foundation | Repository Interfaces | 5 Interface-Dateien |
 | ✓ | A2 | Foundation | Repository Implementations | 5 Repository-Dateien |
-| ☐ | A3 | Foundation | DTOs | 5 DTO-Dateien |
+| ✓ | A3 | Foundation | DTOs | 5 DTO-Dateien |
 | ☐ | A4 | Foundation | Service Interfaces | 5 Service-Interface-Dateien |
 | ☐ | A5 | Foundation | Service Implementations | 5 Service-Dateien |
 | ☐ | A6 | Foundation | AutoMapper Profiles | 5 Mapping-Dateien |
diff --git a/src/Koogle.Application/DTOs/ClubDto.cs b/src/Koogle.Application/DTOs/ClubDto.cs
new file mode 100644
index 0000000..2051f96
--- /dev/null
+++ b/src/Koogle.Application/DTOs/ClubDto.cs
@@ -0,0 +1,25 @@
+using Koogle.Domain.Enums;
+
+namespace Koogle.Application.DTOs;
+
+public record ClubDto
+{
+    public Guid Id { get; init; }
+    public string Name { get; init; } = string.Empty;
+    public ExpenseCalculation ExpenseCalculation { get; init; }
+    public DateTime CreatedAt { get; init; }
+    public DateTime? ModifiedAt { get; init; }
+}
+
+public record CreateClubDto
+{
+    public string Name { get; init; } = string.Empty;
+    public ExpenseCalculation ExpenseCalculation { get; init; } = ExpenseCalculation.None;
+}
+
+public record UpdateClubDto
+{
+    public Guid Id { get; init; }
+    public string Name { get; init; } = string.Empty;
+    public ExpenseCalculation ExpenseCalculation { get; init; }
+}
diff --git a/src/Koogle.Application/DTOs/DayDto.cs b/src/Koogle.Application/DTOs/DayDto.cs
index aa24f58..04ce4e0 100644
--- a/src/Koogle.Application/DTOs/DayDto.cs
+++ b/src/Koogle.Application/DTOs/DayDto.cs
@@ -1,59 +1,62 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
 using Koogle.Domain.Enums;
 
-namespace Koogle.Application.DTOs
+namespace Koogle.Application.DTOs;
+
+public record DayDto
 {
-    public record DayDto
-    {
-        public int Id { get; set; }
-
-        public DateTime PostDate { get; set; }
-
-        public DayStatus Status { get; set; }
-    }
-
-    public record DaySummaryDto
-    {
-        public int Id { get; set; }
-
-        public DateTime PostDate { get; set; }
-
-        public DayStatus Status { get; set; }
-    }
-
-    public record DayFilterDto
-    {
-        public int Year { get; set; }
-
-    //    ///// <summary>
-    //    ///// Sortierfeld.
-    //    ///// </summary>
-    //    //public GoalSortField SortBy { get; init; } = GoalSortField.Name;
-
-    //    ///// <summary>
-    //    ///// Sortierrichtung.
-    //    ///// </summary>
-    //    //public SortDirection SortDirection { get; init; } = SortDirection.Ascending;
-
-    //    // Paginierung
-
-    //    /// <summary>
-    //    /// Seitennummer (1-basiert).
-    //    /// </summary>
-    //    public int Page { get; init; } = 1;
-
-    //    /// <summary>
-    //    /// Anzahl der Einträge pro Seite.
-    //    /// </summary>
-    //    public int PageSize { get; init; } = 20;
-
-    //    /// <summary>
-    //    /// Berechnet den Skip-Wert für die Paginierung.
-    //    /// </summary>
-    //    public int Skip => (Page - 1) * PageSize;
-    }
+    public Guid Id { get; init; }
+    public DateTime PostDate { get; init; }
+    public DayStatus Status { get; init; }
+    public Guid ClubId { get; init; }
+    public string? ClubName { get; init; }
+    public int ParticipantCount { get; init; }
+    public List<DayParticipantDto> Participants { get; init; } = [];
+    public DateTime CreatedAt { get; init; }
+    public DateTime? ModifiedAt { get; init; }
+}
+
+public record DaySummaryDto
+{
+    public Guid Id { get; init; }
+    public DateTime PostDate { get; init; }
+    public DayStatus Status { get; init; }
+    public int ParticipantCount { get; init; }
+}
+
+public record CreateDayDto
+{
+    public DateTime PostDate { get; init; } = DateTime.Today;
+    public List<Guid> ParticipantIds { get; init; } = [];
+}
+
+public record UpdateDayDto
+{
+    public Guid Id { get; init; }
+    public DateTime PostDate { get; init; }
+    public DayStatus Status { get; init; }
+}
+
+public record DayParticipantDto
+{
+    public Guid PersonId { get; init; }
+    public string PersonName { get; init; } = string.Empty;
+    public PersonStatus PersonStatus { get; init; }
+}
+
+public record AddDayParticipantDto
+{
+    public Guid DayId { get; init; }
+    public Guid PersonId { get; init; }
+}
+
+public record RemoveDayParticipantDto
+{
+    public Guid DayId { get; init; }
+    public Guid PersonId { get; init; }
+}
+
+public record DayFilterDto
+{
+    public int? Year { get; init; }
+    public DayStatus? Status { get; init; }
 }
diff --git a/src/Koogle.Application/DTOs/ExpenseDto.cs b/src/Koogle.Application/DTOs/ExpenseDto.cs
new file mode 100644
index 0000000..bc51b1c
--- /dev/null
+++ b/src/Koogle.Application/DTOs/ExpenseDto.cs
@@ -0,0 +1,49 @@
+using Koogle.Domain.Enums;
+
+namespace Koogle.Application.DTOs;
+
+public record ExpenseDto
+{
+    public Guid Id { get; init; }
+    public string Name { get; init; } = string.Empty;
+    public string Description { get; init; } = string.Empty;
+    public decimal Price { get; init; }
+    public bool IsOneClick { get; init; }
+    public bool IsInverse { get; init; }
+    public bool IsVariable { get; init; }
+    public ExpenseType ExpenseType { get; init; }
+    public Guid ClubId { get; init; }
+    public DateTime CreatedAt { get; init; }
+    public DateTime? ModifiedAt { get; init; }
+}
+
+public record CreateExpenseDto
+{
+    public string Name { get; init; } = string.Empty;
+    public string Description { get; init; } = string.Empty;
+    public decimal Price { get; init; }
+    public bool IsOneClick { get; init; }
+    public bool IsInverse { get; init; }
+    public bool IsVariable { get; init; }
+    public ExpenseType ExpenseType { get; init; } = ExpenseType.Monetary;
+}
+
+public record UpdateExpenseDto
+{
+    public Guid Id { get; init; }
+    public string Name { get; init; } = string.Empty;
+    public string Description { get; init; } = string.Empty;
+    public decimal Price { get; init; }
+    public bool IsOneClick { get; init; }
+    public bool IsInverse { get; init; }
+    public bool IsVariable { get; init; }
+    public ExpenseType ExpenseType { get; init; }
+}
+
+public record ExpenseSummaryDto
+{
+    public Guid Id { get; init; }
+    public string Name { get; init; } = string.Empty;
+    public decimal Price { get; init; }
+    public bool IsOneClick { get; init; }
+}
diff --git a/src/Koogle.Application/DTOs/PersonDto.cs b/src/Koogle.Application/DTOs/PersonDto.cs
new file mode 100644
index 0000000..0819c9a
--- /dev/null
+++ b/src/Koogle.Application/DTOs/PersonDto.cs
@@ -0,0 +1,34 @@
+using Koogle.Domain.Enums;
+
+namespace Koogle.Application.DTOs;
+
+public record PersonDto
+{
+    public Guid Id { get; init; }
+    public string Name { get; init; } = string.Empty;
+    public PersonStatus PersonStatus { get; init; }
+    public Guid ClubId { get; init; }
+    public string? ClubName { get; init; }
+    public DateTime CreatedAt { get; init; }
+    public DateTime? ModifiedAt { get; init; }
+}
+
+public record CreatePersonDto
+{
+    public string Name { get; init; } = string.Empty;
+    public PersonStatus PersonStatus { get; init; } = PersonStatus.Member;
+}
+
+public record UpdatePersonDto
+{
+    public Guid Id { get; init; }
+    public string Name { get; init; } = string.Empty;
+    public PersonStatus PersonStatus { get; init; }
+}
+
+public record PersonSummaryDto
+{
+    public Guid Id { get; init; }
+    public string Name { get; init; } = string.Empty;
+    public PersonStatus PersonStatus { get; init; }
+}
diff --git a/src/Koogle.Application/DTOs/PersonExpenseDto.cs b/src/Koogle.Application/DTOs/PersonExpenseDto.cs
new file mode 100644
index 0000000..c735116
--- /dev/null
+++ b/src/Koogle.Application/DTOs/PersonExpenseDto.cs
@@ -0,0 +1,75 @@
+using Koogle.Domain.Enums;
+
+namespace Koogle.Application.DTOs;
+
+public record PersonExpenseDto
+{
+    public Guid Id { get; init; }
+    public Guid PersonId { get; init; }
+    public string PersonName { get; init; } = string.Empty;
+    public Guid ExpenseId { get; init; }
+    public Guid DayId { get; init; }
+    public DateTime DayPostDate { get; init; }
+    public Guid? GameId { get; init; }
+    public Guid ClubId { get; init; }
+    public string Name { get; init; } = string.Empty;
+    public decimal Price { get; init; }
+    public ExpenseType ExpenseType { get; init; }
+    public PersonExpenseStatus PersonExpenseStatus { get; init; }
+    public Guid AssignedById { get; init; }
+    public DateTime CreatedAt { get; init; }
+}
+
+public record CreatePersonExpenseDto
+{
+    public Guid PersonId { get; init; }
+    public Guid ExpenseId { get; init; }
+    public Guid DayId { get; init; }
+    public Guid? GameId { get; init; }
+    public decimal? Price { get; init; } // Override if IsVariable
+}
+
+public record CreateInversePersonExpenseDto
+{
+    public Guid ExcludedPersonId { get; init; } // Person who does NOT get the expense
+    public Guid ExpenseId { get; init; }
+    public Guid DayId { get; init; }
+    public Guid? GameId { get; init; }
+}
+
+public record UpdatePersonExpenseStatusDto
+{
+    public Guid Id { get; init; }
+    public PersonExpenseStatus Status { get; init; }
+}
+
+public record DayEvaluationDto
+{
+    public Guid DayId { get; init; }
+    public DateTime PostDate { get; init; }
+    public DayStatus Status { get; init; }
+    public decimal TotalAmount { get; init; }
+    public int ExpenseCount { get; init; }
+    public List<PersonDayEvaluationDto> PersonEvaluations { get; init; } = [];
+}
+
+public record PersonDayEvaluationDto
+{
+    public Guid PersonId { get; init; }
+    public string PersonName { get; init; } = string.Empty;
+    public decimal TotalAmount { get; init; }
+    public decimal OpenAmount { get; init; }
+    public decimal PaidAmount { get; init; }
+    public int ExpenseCount { get; init; }
+    public List<PersonExpenseDto> Expenses { get; init; } = [];
+}
+
+public record PersonEvaluationSummaryDto
+{
+    public Guid PersonId { get; init; }
+    public string PersonName { get; init; } = string.Empty;
+    public decimal TotalOpenAmount { get; init; }
+    public decimal TotalPaidAmount { get; init; }
+    public int TotalExpenseCount { get; init; }
+    public int DaysParticipated { get; init; }
+}