diff --git a/services/domain/Big.Tests/RegistrationTests.cs b/services/domain/Big.Tests/RegistrationTests.cs
index 2221201..48ef524 100644
--- a/services/domain/Big.Tests/RegistrationTests.cs
+++ b/services/domain/Big.Tests/RegistrationTests.cs
@@ -217,4 +217,72 @@ public class RegistrationTests
         Assert.Contains("Afgewezen", rejectEx.Message);
         Assert.Equal(RegistrationStatus.Afgewezen, registration.Status);
     }
+
+    [Fact]
+    public void Withdrawing_an_ingediend_registration_sets_it_ingetrokken()
+    {
+        var registration = Registration.Submit("123456782");
+
+        registration.Withdraw();
+
+        Assert.Equal(RegistrationStatus.Ingetrokken, registration.Status);
+    }
+
+    [Fact]
+    public void Withdrawing_an_in_behandeling_registration_sets_it_ingetrokken()
+    {
+        // A citizen can still pull a registration back while a behandelaar has it in behandeling.
+        var registration = Registration.Submit("123456782");
+        registration.TakeIntoBehandeling();
+
+        registration.Withdraw();
+
+        Assert.Equal(RegistrationStatus.Ingetrokken, registration.Status);
+    }
+
+    [Fact]
+    public void Withdrawing_needs_no_zaak()
+    {
+        // Withdrawal is the citizen's own action and does not depend on the zaak having been opened.
+        var registration = Registration.Submit("123456782");
+
+        registration.Withdraw();
+
+        Assert.Equal(RegistrationStatus.Ingetrokken, registration.Status);
+        Assert.Null(registration.ZaakUrl);
+    }
+
+    [Fact]
+    public void Re_withdrawing_an_already_ingetrokken_registration_is_idempotent()
+    {
+        var registration = Registration.Submit("123456782");
+        registration.Withdraw();
+
+        registration.Withdraw();
+
+        Assert.Equal(RegistrationStatus.Ingetrokken, registration.Status);
+    }
+
+    [Fact]
+    public void Withdrawing_an_approved_registration_is_rejected()
+    {
+        var registration = Registration.Submit("123456782");
+        registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
+        registration.Approve();
+
+        var ex = Assert.Throws<InvalidOperationException>(() => registration.Withdraw());
+        Assert.Contains("only an INGEDIEND", ex.Message);
+        Assert.Equal(RegistrationStatus.Ingeschreven, registration.Status);
+    }
+
+    [Fact]
+    public void Withdrawing_a_rejected_registration_is_rejected()
+    {
+        var registration = Registration.Submit("123456782");
+        registration.Reject();
+
+        var ex = Assert.Throws<InvalidOperationException>(() => registration.Withdraw());
+        Assert.Contains("only an INGEDIEND", ex.Message);
+        Assert.Equal(RegistrationStatus.Afgewezen, registration.Status);
+    }
 }
diff --git a/services/domain/Big.Tests/WithdrawRegistrationTests.cs b/services/domain/Big.Tests/WithdrawRegistrationTests.cs
new file mode 100644
index 0000000..0506db0
--- /dev/null
+++ b/services/domain/Big.Tests/WithdrawRegistrationTests.cs
@@ -0,0 +1,60 @@
+using Big.Application;
+using Big.Domain;
+
+namespace Big.Tests;
+
+public class WithdrawRegistrationTests
+{
+    [Fact]
+    public async Task Withdrawing_marks_the_registration_ingetrokken_and_persists_it()
+    {
+        var store = new FakeRegistrationStore();
+        var registration = Registration.Submit("123456782");
+        store.Seed(registration);
+        var handler = new WithdrawRegistration(store);
+
+        await handler.HandleAsync(new WithdrawRegistrationCommand(registration.Id));
+
+        var saved = await store.GetAsync(registration.Id);
+        Assert.Equal(RegistrationStatus.Ingetrokken, saved!.Status);
+        Assert.Equal(1, store.SaveCount);
+    }
+
+    [Fact]
+    public async Task Rejects_a_null_command_without_touching_the_store()
+    {
+        var store = new FakeRegistrationStore();
+        var handler = new WithdrawRegistration(store);
+
+        await Assert.ThrowsAsync<ArgumentNullException>(() => handler.HandleAsync(null!));
+        Assert.Equal(0, store.SaveCount);
+    }
+
+    [Fact]
+    public async Task Withdrawing_an_unknown_registration_throws()
+    {
+        var store = new FakeRegistrationStore();
+        var handler = new WithdrawRegistration(store);
+
+        var ex = await Assert.ThrowsAsync<InvalidOperationException>(
+            () => handler.HandleAsync(new WithdrawRegistrationCommand(RegistrationId.New())));
+        Assert.Contains("No registration", ex.Message);
+        Assert.Equal(0, store.SaveCount);
+    }
+
+    [Fact]
+    public async Task Re_withdrawing_an_already_ingetrokken_registration_is_idempotent()
+    {
+        var store = new FakeRegistrationStore();
+        var registration = Registration.Submit("123456782");
+        store.Seed(registration);
+        var handler = new WithdrawRegistration(store);
+
+        await handler.HandleAsync(new WithdrawRegistrationCommand(registration.Id));
+        await handler.HandleAsync(new WithdrawRegistrationCommand(registration.Id));
+
+        // The second withdrawal is a no-op: the aggregate is not persisted again.
+        Assert.Equal(1, store.SaveCount);
+        Assert.Equal(RegistrationStatus.Ingetrokken, (await store.GetAsync(registration.Id))!.Status);
+    }
+}