diff --git a/DocumentOperator.Application/Common/DTOs/SwissQrBillDto.cs b/DocumentOperator.Application/Common/DTOs/SwissQrBillDto.cs
new file mode 100644
index 0000000..3f39430
--- /dev/null
+++ b/DocumentOperator.Application/Common/DTOs/SwissQrBillDto.cs
@@ -0,0 +1,93 @@
+namespace DocumentOperator.Application.Common.DTOs;
+
+/// <summary>
+/// Swiss QR Bill data transfer object (mapped from Codecrete Bill)
+/// </summary>
+public record SwissQrBillDto
+{
+    /// <summary>QR Bill standard version (e.g., "V2_0")</summary>
+    public required string Version { get; init; }
+
+    /// <summary>Payment amount (null if not specified)</summary>
+    public decimal? Amount { get; init; }
+
+    /// <summary>Payment currency (CHF or EUR)</summary>
+    public required string Currency { get; init; }
+
+    /// <summary>Creditor's IBAN account number</summary>
+    public required string Account { get; init; }
+
+    /// <summary>Creditor address</summary>
+    public required AddressDto Creditor { get; init; }
+
+    /// <summary>Payment reference type: "QRR", "SCOR", or "NON"</summary>
+    public required string ReferenceType { get; init; }
+
+    /// <summary>Payment reference (format depends on ReferenceType)</summary>
+    public string? Reference { get; init; }
+
+    /// <summary>Debtor address (optional)</summary>
+    public AddressDto? Debtor { get; init; }
+
+    /// <summary>Additional unstructured message (max 140 chars)</summary>
+    public string? UnstructuredMessage { get; init; }
+
+    /// <summary>Additional structured bill information</summary>
+    public string? BillInformation { get; init; }
+
+    /// <summary>Alternative payment schemes (max 2)</summary>
+    public IReadOnlyList<AlternativeSchemeDto>? AlternativeSchemes { get; init; }
+}
+
+/// <summary>
+/// Address data transfer object (mapped from Codecrete Address)
+/// </summary>
+public record AddressDto
+{
+    /// <summary>Address type: "Structured" or "CombinedElements"</summary>
+    public required string Type { get; init; }
+
+    /// <summary>Name of person or company</summary>
+    public required string Name { get; init; }
+
+    /// <summary>Street name (structured address only)</summary>
+    public string? Street { get; init; }
+
+    /// <summary>House number (structured address only)</summary>
+    public string? HouseNo { get; init; }
+
+    /// <summary>
+    /// Address line 1 (combined address only).
+    /// OBSOLETE: Use structured address instead. Will be removed when Codecrete v4 is adopted.
+    /// </summary>
+    [Obsolete("Use structured address (Street + HouseNo) instead. This field will be removed when upgrading to Codecrete.SwissQRBill.Generator v4.x")]
+    public string? AddressLine1 { get; init; }
+
+    /// <summary>
+    /// Address line 2 (combined address only).
+    /// OBSOLETE: Use structured address instead. Will be removed when Codecrete v4 is adopted.
+    /// </summary>
+    [Obsolete("Use structured address (Street + HouseNo) instead. This field will be removed when upgrading to Codecrete.SwissQRBill.Generator v4.x")]
+    public string? AddressLine2 { get; init; }
+
+    /// <summary>Postal code</summary>
+    public required string PostalCode { get; init; }
+
+    /// <summary>Town/city name</summary>
+    public required string Town { get; init; }
+
+    /// <summary>Two-letter country code (ISO 3166-1 alpha-2)</summary>
+    public required string CountryCode { get; init; }
+}
+
+/// <summary>
+/// Alternative payment scheme (mapped from Codecrete AlternativeScheme)
+/// </summary>
+public record AlternativeSchemeDto
+{
+    /// <summary>Scheme name (e.g., "AV1", "AV2")</summary>
+    public required string Name { get; init; }
+
+    /// <summary>Scheme instruction/parameter</summary>
+    public required string Instruction { get; init; }
+}
diff --git a/DocumentOperator.Domain/Common/Exceptions/BadRequestException.cs b/DocumentOperator.Domain/Common/Exceptions/BadRequestException.cs
new file mode 100644
index 0000000..7fb8f12
--- /dev/null
+++ b/DocumentOperator.Domain/Common/Exceptions/BadRequestException.cs
@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Runtime.Serialization;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace DocumentOperator.Domain.Common.Exceptions;
+
+public class BadRequestException : Exception
+{
+    public BadRequestException()
+    {
+    }
+
+    public BadRequestException(string? message) : base(message)
+    {
+    }
+
+    public BadRequestException(string? message, Exception? innerException) : base(message, innerException)
+    {
+    }
+}