diff --git a/src/api/SIGCM2.Api/Filters/ExceptionFilter.cs b/src/api/SIGCM2.Api/Filters/ExceptionFilter.cs
index bf0f054..f43eac9 100644
--- a/src/api/SIGCM2.Api/Filters/ExceptionFilter.cs
+++ b/src/api/SIGCM2.Api/Filters/ExceptionFilter.cs
@@ -169,6 +169,79 @@ public sealed class ExceptionFilter : IExceptionFilter
                 context.ExceptionHandled = true;
                 break;
 
+            // CAT-001: Rubro exceptions
+            case RubroNotFoundException rubroNotFoundEx:
+                context.Result = new ObjectResult(new
+                {
+                    error = "rubro_not_found",
+                    message = rubroNotFoundEx.Message
+                })
+                {
+                    StatusCode = StatusCodes.Status404NotFound
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case RubroNombreDuplicadoEnPadreException rubroDupEx:
+                context.Result = new ObjectResult(new
+                {
+                    error = "rubro_nombre_duplicado",
+                    message = rubroDupEx.Message
+                })
+                {
+                    StatusCode = StatusCodes.Status409Conflict
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case RubroTieneHijosActivosException rubroHijosEx:
+                context.Result = new ObjectResult(new
+                {
+                    error = "rubro_tiene_hijos_activos",
+                    message = rubroHijosEx.Message
+                })
+                {
+                    StatusCode = StatusCodes.Status409Conflict
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case RubroPadreInactivoException rubroPadreEx:
+                context.Result = new ObjectResult(new
+                {
+                    error = "rubro_padre_inactivo",
+                    message = rubroPadreEx.Message
+                })
+                {
+                    StatusCode = StatusCodes.Status400BadRequest
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case RubroMaxDepthExceededException rubroDepthEx:
+                context.Result = new ObjectResult(new
+                {
+                    error = "rubro_max_depth_exceeded",
+                    message = rubroDepthEx.Message
+                })
+                {
+                    StatusCode = StatusCodes.Status422UnprocessableEntity
+                };
+                context.ExceptionHandled = true;
+                break;
+
+            case RubroCycleDetectedException rubroCycleEx:
+                context.Result = new ObjectResult(new
+                {
+                    error = "rubro_cycle_detected",
+                    message = rubroCycleEx.Message
+                })
+                {
+                    StatusCode = StatusCodes.Status400BadRequest
+                };
+                context.ExceptionHandled = true;
+                break;
+
             // ADM-001: Medio exceptions
             case MedioCodigoDuplicadoException medioCodDupEx:
                 context.Result = new ObjectResult(new
diff --git a/src/api/SIGCM2.Domain/Entities/Rubro.cs b/src/api/SIGCM2.Domain/Entities/Rubro.cs
new file mode 100644
index 0000000..582a7a0
--- /dev/null
+++ b/src/api/SIGCM2.Domain/Entities/Rubro.cs
@@ -0,0 +1,139 @@
+namespace SIGCM2.Domain.Entities;
+
+/// <summary>
+/// Immutable N-ary tree node for the commercial catalog taxonomy.
+/// Follows the same sealed-class + factory + with-methods pattern as Medio.cs.
+/// </summary>
+public sealed class Rubro
+{
+    private const int NombreMaxLength = 200;
+
+    public int Id { get; }
+    public int? ParentId { get; }
+    public string Nombre { get; }
+    public int Orden { get; }
+    public bool Activo { get; }
+    public int? TarifarioBaseId { get; }
+    public DateTime FechaCreacion { get; }
+    public DateTime? FechaModificacion { get; }
+
+    /// <summary>
+    /// Full hydration constructor — used by the repository to reconstruct from DB rows.
+    /// </summary>
+    public Rubro(
+        int id,
+        int? parentId,
+        string nombre,
+        int orden,
+        bool activo,
+        int? tarifarioBaseId,
+        DateTime fechaCreacion,
+        DateTime? fechaModificacion)
+    {
+        Id = id;
+        ParentId = parentId;
+        Nombre = nombre;
+        Orden = orden;
+        Activo = activo;
+        TarifarioBaseId = tarifarioBaseId;
+        FechaCreacion = fechaCreacion;
+        FechaModificacion = fechaModificacion;
+    }
+
+    /// <summary>
+    /// Factory for creating a new Rubro.
+    /// Id=0 — DB assigns via IDENTITY.
+    /// Activo=true, FechaModificacion=null by default.
+    /// FechaCreacion is set from TimeProvider so it is testable.
+    /// </summary>
+    public static Rubro ForCreation(
+        string nombre,
+        int? parentId,
+        int orden,
+        int? tarifarioBaseId,
+        TimeProvider timeProvider)
+    {
+        ValidateNombre(nombre);
+
+        if (parentId.HasValue && parentId.Value <= 0)
+            throw new ArgumentException("parentId debe ser un entero positivo cuando no es nulo.", nameof(parentId));
+
+        if (tarifarioBaseId.HasValue && tarifarioBaseId.Value < 0)
+            throw new ArgumentException("tarifarioBaseId no puede ser negativo.", nameof(tarifarioBaseId));
+
+        return new Rubro(
+            id: 0,
+            parentId: parentId,
+            nombre: nombre,
+            orden: orden,
+            activo: true,
+            tarifarioBaseId: tarifarioBaseId,
+            fechaCreacion: timeProvider.GetUtcNow().UtcDateTime,
+            fechaModificacion: null);
+    }
+
+    /// <summary>
+    /// Returns a new Rubro instance with an updated Nombre and FechaModificacion.
+    /// Does NOT mutate the current instance.
+    /// </summary>
+    public Rubro WithRenamed(string nuevoNombre, TimeProvider timeProvider)
+    {
+        ValidateNombre(nuevoNombre);
+
+        return new Rubro(
+            id: Id,
+            parentId: ParentId,
+            nombre: nuevoNombre,
+            orden: Orden,
+            activo: Activo,
+            tarifarioBaseId: TarifarioBaseId,
+            fechaCreacion: FechaCreacion,
+            fechaModificacion: timeProvider.GetUtcNow().UtcDateTime);
+    }
+
+    /// <summary>
+    /// Returns a new Rubro instance with updated ParentId and Orden.
+    /// Does NOT mutate the current instance.
+    /// </summary>
+    public Rubro WithMoved(int? nuevoParentId, int nuevoOrden, TimeProvider timeProvider)
+    {
+        return new Rubro(
+            id: Id,
+            parentId: nuevoParentId,
+            nombre: Nombre,
+            orden: nuevoOrden,
+            activo: Activo,
+            tarifarioBaseId: TarifarioBaseId,
+            fechaCreacion: FechaCreacion,
+            fechaModificacion: timeProvider.GetUtcNow().UtcDateTime);
+    }
+
+    /// <summary>
+    /// Returns a new Rubro instance with updated Activo flag.
+    /// Use Deactivate (false) or Reactivate (true).
+    /// Does NOT mutate the current instance.
+    /// </summary>
+    public Rubro WithActivo(bool activo, TimeProvider timeProvider)
+    {
+        return new Rubro(
+            id: Id,
+            parentId: ParentId,
+            nombre: Nombre,
+            orden: Orden,
+            activo: activo,
+            tarifarioBaseId: TarifarioBaseId,
+            fechaCreacion: FechaCreacion,
+            fechaModificacion: timeProvider.GetUtcNow().UtcDateTime);
+    }
+
+    private static void ValidateNombre(string nombre)
+    {
+        if (string.IsNullOrWhiteSpace(nombre))
+            throw new ArgumentException("El nombre del rubro no puede estar vacío o ser solo espacios.", nameof(nombre));
+
+        if (nombre.Length > NombreMaxLength)
+            throw new ArgumentException(
+                $"El nombre del rubro no puede superar los {NombreMaxLength} caracteres.",
+                nameof(nombre));
+    }
+}
diff --git a/src/api/SIGCM2.Domain/Exceptions/RubroCycleDetectedException.cs b/src/api/SIGCM2.Domain/Exceptions/RubroCycleDetectedException.cs
new file mode 100644
index 0000000..c86a387
--- /dev/null
+++ b/src/api/SIGCM2.Domain/Exceptions/RubroCycleDetectedException.cs
@@ -0,0 +1,17 @@
+namespace SIGCM2.Domain.Exceptions;
+
+/// <summary>
+/// Thrown when moving a Rubro to one of its own descendants would create a cycle. → HTTP 400
+/// </summary>
+public sealed class RubroCycleDetectedException : DomainException
+{
+    public int RubroId { get; }
+    public int NuevoParentId { get; }
+
+    public RubroCycleDetectedException(int rubroId, int nuevoParentId)
+        : base($"Mover el rubro '{rubroId}' al padre '{nuevoParentId}' crearía un ciclo en el árbol.")
+    {
+        RubroId = rubroId;
+        NuevoParentId = nuevoParentId;
+    }
+}
diff --git a/src/api/SIGCM2.Domain/Exceptions/RubroMaxDepthExceededException.cs b/src/api/SIGCM2.Domain/Exceptions/RubroMaxDepthExceededException.cs
new file mode 100644
index 0000000..d993955
--- /dev/null
+++ b/src/api/SIGCM2.Domain/Exceptions/RubroMaxDepthExceededException.cs
@@ -0,0 +1,17 @@
+namespace SIGCM2.Domain.Exceptions;
+
+/// <summary>
+/// Thrown when creating or moving a Rubro would exceed the configured maximum tree depth. → HTTP 422
+/// </summary>
+public sealed class RubroMaxDepthExceededException : DomainException
+{
+    public int Intentada { get; }
+    public int Max { get; }
+
+    public RubroMaxDepthExceededException(int intentada, int max)
+        : base($"La profundidad intentada ({intentada}) excede el máximo permitido ({max}).")
+    {
+        Intentada = intentada;
+        Max = max;
+    }
+}
diff --git a/src/api/SIGCM2.Domain/Exceptions/RubroNombreDuplicadoEnPadreException.cs b/src/api/SIGCM2.Domain/Exceptions/RubroNombreDuplicadoEnPadreException.cs
new file mode 100644
index 0000000..1b0b284
--- /dev/null
+++ b/src/api/SIGCM2.Domain/Exceptions/RubroNombreDuplicadoEnPadreException.cs
@@ -0,0 +1,19 @@
+namespace SIGCM2.Domain.Exceptions;
+
+/// <summary>
+/// Thrown when a Rubro with the same Nombre (CI) already exists under the same parent. → HTTP 409
+/// </summary>
+public sealed class RubroNombreDuplicadoEnPadreException : DomainException
+{
+    public string Nombre { get; }
+    public int? ParentId { get; }
+
+    public RubroNombreDuplicadoEnPadreException(string nombre, int? parentId)
+        : base(parentId.HasValue
+            ? $"Ya existe un rubro con el nombre '{nombre}' bajo el padre con id '{parentId}'."
+            : $"Ya existe un rubro raíz con el nombre '{nombre}'.")
+    {
+        Nombre = nombre;
+        ParentId = parentId;
+    }
+}
diff --git a/src/api/SIGCM2.Domain/Exceptions/RubroNotFoundException.cs b/src/api/SIGCM2.Domain/Exceptions/RubroNotFoundException.cs
new file mode 100644
index 0000000..c1b4f28
--- /dev/null
+++ b/src/api/SIGCM2.Domain/Exceptions/RubroNotFoundException.cs
@@ -0,0 +1,15 @@
+namespace SIGCM2.Domain.Exceptions;
+
+/// <summary>
+/// Thrown when a requested Rubro does not exist in the system. → HTTP 404
+/// </summary>
+public sealed class RubroNotFoundException : DomainException
+{
+    public int Id { get; }
+
+    public RubroNotFoundException(int id)
+        : base($"El rubro con id '{id}' no existe.")
+    {
+        Id = id;
+    }
+}
diff --git a/src/api/SIGCM2.Domain/Exceptions/RubroPadreInactivoException.cs b/src/api/SIGCM2.Domain/Exceptions/RubroPadreInactivoException.cs
new file mode 100644
index 0000000..08bf642
--- /dev/null
+++ b/src/api/SIGCM2.Domain/Exceptions/RubroPadreInactivoException.cs
@@ -0,0 +1,15 @@
+namespace SIGCM2.Domain.Exceptions;
+
+/// <summary>
+/// Thrown when attempting to create or move a Rubro under an inactive parent. → HTTP 400
+/// </summary>
+public sealed class RubroPadreInactivoException : DomainException
+{
+    public int ParentId { get; }
+
+    public RubroPadreInactivoException(int parentId)
+        : base($"El padre con id '{parentId}' está inactivo y no puede tener hijos.")
+    {
+        ParentId = parentId;
+    }
+}
diff --git a/src/api/SIGCM2.Domain/Exceptions/RubroTieneHijosActivosException.cs b/src/api/SIGCM2.Domain/Exceptions/RubroTieneHijosActivosException.cs
new file mode 100644
index 0000000..4df437f
--- /dev/null
+++ b/src/api/SIGCM2.Domain/Exceptions/RubroTieneHijosActivosException.cs
@@ -0,0 +1,17 @@
+namespace SIGCM2.Domain.Exceptions;
+
+/// <summary>
+/// Thrown when attempting to soft-delete a Rubro that still has active children. → HTTP 409
+/// </summary>
+public sealed class RubroTieneHijosActivosException : DomainException
+{
+    public int Id { get; }
+    public int Count { get; }
+
+    public RubroTieneHijosActivosException(int id, int count)
+        : base($"El rubro con id '{id}' tiene {count} subrubros activos.")
+    {
+        Id = id;
+        Count = count;
+    }
+}
diff --git a/tests/SIGCM2.Application.Tests/Domain/Rubros/RubroExceptionsTests.cs b/tests/SIGCM2.Application.Tests/Domain/Rubros/RubroExceptionsTests.cs
new file mode 100644
index 0000000..e55a283
--- /dev/null
+++ b/tests/SIGCM2.Application.Tests/Domain/Rubros/RubroExceptionsTests.cs
@@ -0,0 +1,137 @@
+using FluentAssertions;
+using SIGCM2.Domain.Exceptions;
+
+namespace SIGCM2.Application.Tests.Domain.Rubros;
+
+public class RubroExceptionsTests
+{
+    // ── RubroNotFoundException ───────────────────────────────────────────────
+
+    [Fact]
+    public void RubroNotFoundException_ContainsId()
+    {
+        var ex = new RubroNotFoundException(42);
+
+        ex.Id.Should().Be(42);
+        ex.Message.Should().Contain("42");
+    }
+
+    [Fact]
+    public void RubroNotFoundException_InheritsFromDomainException()
+    {
+        var ex = new RubroNotFoundException(1);
+
+        ex.Should().BeAssignableTo<DomainException>();
+    }
+
+    // ── RubroNombreDuplicadoEnPadreException ─────────────────────────────────
+
+    [Fact]
+    public void RubroNombreDuplicadoEnPadreException_ContainsNombreAndParentId()
+    {
+        var ex = new RubroNombreDuplicadoEnPadreException("Autos", parentId: 5);
+
+        ex.Nombre.Should().Be("Autos");
+        ex.ParentId.Should().Be(5);
+        ex.Message.Should().Contain("Autos");
+    }
+
+    [Fact]
+    public void RubroNombreDuplicadoEnPadreException_WithNullParent_IsValid()
+    {
+        var ex = new RubroNombreDuplicadoEnPadreException("Autos", parentId: null);
+
+        ex.Nombre.Should().Be("Autos");
+        ex.ParentId.Should().BeNull();
+    }
+
+    [Fact]
+    public void RubroNombreDuplicadoEnPadreException_InheritsFromDomainException()
+    {
+        var ex = new RubroNombreDuplicadoEnPadreException("x", null);
+
+        ex.Should().BeAssignableTo<DomainException>();
+    }
+
+    // ── RubroMaxDepthExceededException ───────────────────────────────────────
+
+    [Fact]
+    public void RubroMaxDepthExceededException_ContainsDepthInfo()
+    {
+        var ex = new RubroMaxDepthExceededException(intentada: 11, max: 10);
+
+        ex.Intentada.Should().Be(11);
+        ex.Max.Should().Be(10);
+        ex.Message.Should().Contain("11");
+        ex.Message.Should().Contain("10");
+    }
+
+    [Fact]
+    public void RubroMaxDepthExceededException_InheritsFromDomainException()
+    {
+        var ex = new RubroMaxDepthExceededException(11, 10);
+
+        ex.Should().BeAssignableTo<DomainException>();
+    }
+
+    // ── RubroCycleDetectedException ──────────────────────────────────────────
+
+    [Fact]
+    public void RubroCycleDetectedException_ContainsRubroIdAndIntendedParentId()
+    {
+        var ex = new RubroCycleDetectedException(rubroId: 5, nuevoParentId: 10);
+
+        ex.RubroId.Should().Be(5);
+        ex.NuevoParentId.Should().Be(10);
+        ex.Message.Should().Contain("5");
+        ex.Message.Should().Contain("10");
+    }
+
+    [Fact]
+    public void RubroCycleDetectedException_InheritsFromDomainException()
+    {
+        var ex = new RubroCycleDetectedException(1, 2);
+
+        ex.Should().BeAssignableTo<DomainException>();
+    }
+
+    // ── RubroTieneHijosActivosException ─────────────────────────────────────
+
+    [Fact]
+    public void RubroTieneHijosActivosException_ContainsIdAndCount()
+    {
+        var ex = new RubroTieneHijosActivosException(id: 7, count: 3);
+
+        ex.Id.Should().Be(7);
+        ex.Count.Should().Be(3);
+        ex.Message.Should().Contain("3");
+        ex.Message.Should().Contain("subrubros");
+    }
+
+    [Fact]
+    public void RubroTieneHijosActivosException_InheritsFromDomainException()
+    {
+        var ex = new RubroTieneHijosActivosException(1, 2);
+
+        ex.Should().BeAssignableTo<DomainException>();
+    }
+
+    // ── RubroPadreInactivoException ──────────────────────────────────────────
+
+    [Fact]
+    public void RubroPadreInactivoException_ContainsParentId()
+    {
+        var ex = new RubroPadreInactivoException(parentId: 9);
+
+        ex.ParentId.Should().Be(9);
+        ex.Message.Should().Contain("9");
+    }
+
+    [Fact]
+    public void RubroPadreInactivoException_InheritsFromDomainException()
+    {
+        var ex = new RubroPadreInactivoException(1);
+
+        ex.Should().BeAssignableTo<DomainException>();
+    }
+}
diff --git a/tests/SIGCM2.Application.Tests/Domain/Rubros/RubroTests.cs b/tests/SIGCM2.Application.Tests/Domain/Rubros/RubroTests.cs
new file mode 100644
index 0000000..2688bfd
--- /dev/null
+++ b/tests/SIGCM2.Application.Tests/Domain/Rubros/RubroTests.cs
@@ -0,0 +1,171 @@
+using FluentAssertions;
+using Microsoft.Extensions.Time.Testing;
+using SIGCM2.Domain.Entities;
+
+namespace SIGCM2.Application.Tests.Domain.Rubros;
+
+public class RubroTests
+{
+    private static readonly FakeTimeProvider FakeTime = new(new DateTimeOffset(2026, 4, 18, 12, 0, 0, TimeSpan.Zero));
+
+    // ── ForCreation: happy path ──────────────────────────────────────────────
+
+    [Fact]
+    public void Create_con_datos_validos_crea_rubro_activo_con_orden_cero_como_default()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        rubro.Nombre.Should().Be("Autos");
+        rubro.ParentId.Should().BeNull();
+        rubro.Orden.Should().Be(0);
+        rubro.Activo.Should().BeTrue();
+        rubro.TarifarioBaseId.Should().BeNull();
+        rubro.Id.Should().Be(0);
+        rubro.FechaCreacion.Should().Be(FakeTime.GetUtcNow().UtcDateTime);
+        rubro.FechaModificacion.Should().BeNull();
+    }
+
+    [Fact]
+    public void Create_root_con_parentId_null_es_valido()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        rubro.ParentId.Should().BeNull();
+    }
+
+    // ── ForCreation: validations ─────────────────────────────────────────────
+
+    [Fact]
+    public void Create_con_nombre_vacio_lanza_ArgumentException()
+    {
+        var act = () => Rubro.ForCreation("", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        act.Should().Throw<ArgumentException>();
+    }
+
+    [Fact]
+    public void Create_con_nombre_solo_whitespace_lanza_ArgumentException()
+    {
+        var act = () => Rubro.ForCreation("   ", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        act.Should().Throw<ArgumentException>();
+    }
+
+    [Fact]
+    public void Create_con_nombre_excediendo_200_chars_lanza_ArgumentException()
+    {
+        var nombre = new string('A', 201);
+
+        var act = () => Rubro.ForCreation(nombre, parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        act.Should().Throw<ArgumentException>();
+    }
+
+    [Fact]
+    public void Create_con_parentId_menor_o_igual_a_cero_lanza_ArgumentException()
+    {
+        var act = () => Rubro.ForCreation("Autos", parentId: 0, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        act.Should().Throw<ArgumentException>();
+    }
+
+    [Fact]
+    public void Create_con_tarifarioBaseId_menor_a_cero_lanza_ArgumentException()
+    {
+        var act = () => Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: -1, FakeTime);
+
+        act.Should().Throw<ArgumentException>();
+    }
+
+    // ── WithRenamed ──────────────────────────────────────────────────────────
+
+    [Fact]
+    public void Rename_con_nombre_valido_devuelve_nueva_instancia_con_FechaModificacion()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+        var laterTime = new FakeTimeProvider(new DateTimeOffset(2026, 4, 18, 14, 0, 0, TimeSpan.Zero));
+
+        var renamed = rubro.WithRenamed("Vehiculos", laterTime);
+
+        renamed.Nombre.Should().Be("Vehiculos");
+        renamed.FechaModificacion.Should().Be(laterTime.GetUtcNow().UtcDateTime);
+    }
+
+    [Fact]
+    public void Rename_con_nombre_invalido_lanza_ArgumentException()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        var act = () => rubro.WithRenamed("", FakeTime);
+
+        act.Should().Throw<ArgumentException>();
+    }
+
+    [Fact]
+    public void Rename_no_muta_la_instancia_original()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        rubro.WithRenamed("Vehiculos", FakeTime);
+
+        rubro.Nombre.Should().Be("Autos");
+    }
+
+    // ── WithMoved ────────────────────────────────────────────────────────────
+
+    [Fact]
+    public void Move_a_nuevo_parent_devuelve_nueva_instancia_con_parentId_actualizado()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        var moved = rubro.WithMoved(nuevoParentId: 5, nuevoOrden: 2, FakeTime);
+
+        moved.ParentId.Should().Be(5);
+        moved.Orden.Should().Be(2);
+    }
+
+    [Fact]
+    public void Move_a_root_permite_parentId_null()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: 3, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        var moved = rubro.WithMoved(nuevoParentId: null, nuevoOrden: 0, FakeTime);
+
+        moved.ParentId.Should().BeNull();
+    }
+
+    [Fact]
+    public void Move_no_muta_la_instancia_original()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        rubro.WithMoved(nuevoParentId: 5, nuevoOrden: 1, FakeTime);
+
+        rubro.ParentId.Should().BeNull();
+        rubro.Orden.Should().Be(0);
+    }
+
+    // ── WithActivo (Deactivate / Reactivate) ────────────────────────────────
+
+    [Fact]
+    public void Deactivate_flip_Activo_a_false()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+
+        var deactivated = rubro.WithActivo(false, FakeTime);
+
+        deactivated.Activo.Should().BeFalse();
+        deactivated.FechaModificacion.Should().Be(FakeTime.GetUtcNow().UtcDateTime);
+    }
+
+    [Fact]
+    public void Reactivate_flip_Activo_a_true()
+    {
+        var rubro = Rubro.ForCreation("Autos", parentId: null, orden: 0, tarifarioBaseId: null, FakeTime);
+        var deactivated = rubro.WithActivo(false, FakeTime);
+
+        var reactivated = deactivated.WithActivo(true, FakeTime);
+
+        reactivated.Activo.Should().BeTrue();
+    }
+}