diff --git a/services/domain/Big.Application/Ports.cs b/services/domain/Big.Application/Ports.cs
index 8e74b72..b89ac82 100644
--- a/services/domain/Big.Application/Ports.cs
+++ b/services/domain/Big.Application/Ports.cs
@@ -11,10 +11,12 @@ public interface IWorkflowClient
 {
     /// <summary>
     /// Start one <c>registratie</c> process instance for the given registration, carrying the
-    /// registration id so the <c>OpenZaakAanmaken</c> external task can be correlated back to its
-    /// aggregate. Returns the process instance id.
+    /// registration id (so the <c>OpenZaakAanmaken</c> external task can be correlated back to its
+    /// aggregate) and the diploma origin (so the workflow's DMN can route foreign diplomas through
+    /// CBGV-advies, S-13). Returns the process instance id.
     /// </summary>
-    Task<string> StartRegistrationProcessAsync(RegistrationId registrationId, CancellationToken ct = default);
+    Task<string> StartRegistrationProcessAsync(
+        RegistrationId registrationId, DiplomaOrigin diplomaOrigin, CancellationToken ct = default);
 
     /// <summary>
     /// Cancel a running <c>registratie</c> process on withdrawal (S-11): correlate the
diff --git a/services/domain/Big.Application/SubmitRegistration.cs b/services/domain/Big.Application/SubmitRegistration.cs
index 3e2f55f..1f70e9e 100644
--- a/services/domain/Big.Application/SubmitRegistration.cs
+++ b/services/domain/Big.Application/SubmitRegistration.cs
@@ -2,8 +2,10 @@ using Big.Domain;
 
 namespace Big.Application;
 
-/// <summary>A zorgprofessional's request to register, in domain language. No ZGW concepts.</summary>
-public sealed record SubmitRegistrationCommand(string Bsn);
+/// <summary>A zorgprofessional's request to register, in domain language. No ZGW concepts. The
+/// diploma origin defaults to domestic (the DigiD path); a foreign (eIDAS) submission sets it to
+/// <see cref="DiplomaOrigin.Buitenlands"/> so the workflow's DMN routes it through CBGV-advies (S-13).</summary>
+public sealed record SubmitRegistrationCommand(string Bsn, DiplomaOrigin DiplomaOrigin = DiplomaOrigin.Binnenlands);
 
 /// <summary>
 /// The submit use case: create the <see cref="Registration"/> aggregate (INGEDIEND), persist it,
@@ -18,13 +20,14 @@ public sealed class SubmitRegistration(IRegistrationStore store, IWorkflowClient
     {
         ArgumentNullException.ThrowIfNull(command);
 
-        var registration = Registration.Submit(command.Bsn);
+        var registration = Registration.Submit(command.Bsn, command.DiplomaOrigin);
 
         // Persist before starting the process so the worker can correlate the OpenZaakAanmaken
         // job back to an aggregate that already exists (ADR-0009).
         await store.SaveAsync(registration, ct);
 
-        var processInstanceId = await workflow.StartRegistrationProcessAsync(registration.Id, ct);
+        var processInstanceId = await workflow.StartRegistrationProcessAsync(
+            registration.Id, registration.DiplomaOrigin, ct);
         registration.RecordProcessStarted(processInstanceId);
         await store.SaveAsync(registration, ct);
 
diff --git a/services/domain/Big.Domain/DiplomaOrigin.cs b/services/domain/Big.Domain/DiplomaOrigin.cs
new file mode 100644
index 0000000..74812dc
--- /dev/null
+++ b/services/domain/Big.Domain/DiplomaOrigin.cs
@@ -0,0 +1,17 @@
+namespace Big.Domain;
+
+/// <summary>
+/// Where a zorgprofessional's diploma was issued. It is the input to the diploma-eligibility decision
+/// (S-13): a <see cref="Buitenlands"/> (foreign) diploma routes the registratie through an extra
+/// CBGV-advies assessment step, a <see cref="Binnenlands"/> (domestic) one goes straight to beoordeling.
+/// The decision itself lives in the workflow's DMN, not here (ADR-0016); the domain only carries the
+/// origin and hands it to the process as a start variable.
+/// </summary>
+public enum DiplomaOrigin
+{
+    /// <summary>A Dutch (domestic) diploma. Default for a registration submitted via DigiD.</summary>
+    Binnenlands,
+
+    /// <summary>A foreign diploma (e.g. an eIDAS submission). Triggers the CBGV-advies step.</summary>
+    Buitenlands,
+}
diff --git a/services/domain/Big.Domain/Registration.cs b/services/domain/Big.Domain/Registration.cs
index 4b29eab..51f20cf 100644
--- a/services/domain/Big.Domain/Registration.cs
+++ b/services/domain/Big.Domain/Registration.cs
@@ -7,10 +7,11 @@ namespace Big.Domain;
 /// </summary>
 public sealed class Registration
 {
-    private Registration(RegistrationId id, string bsn)
+    private Registration(RegistrationId id, string bsn, DiplomaOrigin diplomaOrigin)
     {
         Id = id;
         Bsn = bsn;
+        DiplomaOrigin = diplomaOrigin;
         Status = RegistrationStatus.Ingediend;
     }
 
@@ -20,6 +21,10 @@ public sealed class Registration
     /// as the domain payload; the domain never constructs ZGW concepts from it (§8.1).</summary>
     public string Bsn { get; }
 
+    /// <summary>Where the diploma was issued. Rides along to the process as a start variable and
+    /// drives the diploma-eligibility DMN's foreign→CBGV-advies routing (S-13, ADR-0016).</summary>
+    public DiplomaOrigin DiplomaOrigin { get; }
+
     public RegistrationStatus Status { get; private set; }
 
     /// <summary>The Flowable process instance driving this registration, once started.</summary>
@@ -28,11 +33,13 @@ public sealed class Registration
     /// <summary>The zaak the ACL opened for this registration, once the external task has run.</summary>
     public Uri? ZaakUrl { get; private set; }
 
-    /// <summary>Submit a new registration. It begins in <see cref="RegistrationStatus.Ingediend"/>.</summary>
-    public static Registration Submit(string bsn)
+    /// <summary>Submit a new registration. It begins in <see cref="RegistrationStatus.Ingediend"/>.
+    /// The diploma origin defaults to <see cref="DiplomaOrigin.Binnenlands"/> — the common DigiD path;
+    /// a foreign (eIDAS) submission passes <see cref="DiplomaOrigin.Buitenlands"/>.</summary>
+    public static Registration Submit(string bsn, DiplomaOrigin diplomaOrigin = DiplomaOrigin.Binnenlands)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(bsn);
-        return new Registration(RegistrationId.New(), bsn);
+        return new Registration(RegistrationId.New(), bsn, diplomaOrigin);
     }
 
     /// <summary>Record that the registratie workflow process has been started for this registration.</summary>
diff --git a/services/domain/Big.Infrastructure/FlowableWorkflowClient.cs b/services/domain/Big.Infrastructure/FlowableWorkflowClient.cs
index d8933e2..1d825c8 100644
--- a/services/domain/Big.Infrastructure/FlowableWorkflowClient.cs
+++ b/services/domain/Big.Infrastructure/FlowableWorkflowClient.cs
@@ -28,7 +28,8 @@ public sealed class FlowableWorkflowClient(HttpClient http, FlowableOptions opti
     private const string BesluitVariable = "besluit";
     private const string IngetrokkenMessage = "RegistratieIngetrokken";
 
-    public async Task<string> StartRegistrationProcessAsync(RegistrationId registrationId, CancellationToken ct = default)
+    public async Task<string> StartRegistrationProcessAsync(
+        RegistrationId registrationId, DiplomaOrigin diplomaOrigin, CancellationToken ct = default)
     {
         var request = new StartProcessRequest(
             ProcessDefinitionKey,
diff --git a/services/domain/Big.Tests/Fakes.cs b/services/domain/Big.Tests/Fakes.cs
index 539f554..e9c6953 100644
--- a/services/domain/Big.Tests/Fakes.cs
+++ b/services/domain/Big.Tests/Fakes.cs
@@ -32,12 +32,15 @@ internal sealed class FakeWorkflowClient(string processInstanceId = "proc-1", Ac
     : IWorkflowClient
 {
     public RegistrationId? StartedFor { get; private set; }
+    public DiplomaOrigin? StartedWithOrigin { get; private set; }
     public string? WithdrawnProcessInstanceId { get; private set; }
 
-    public Task<string> StartRegistrationProcessAsync(RegistrationId registrationId, CancellationToken ct = default)
+    public Task<string> StartRegistrationProcessAsync(
+        RegistrationId registrationId, DiplomaOrigin diplomaOrigin, CancellationToken ct = default)
     {
         onStart?.Invoke(registrationId);
         StartedFor = registrationId;
+        StartedWithOrigin = diplomaOrigin;
         return Task.FromResult(processInstanceId);
     }
 
diff --git a/services/domain/Big.Tests/FlowableWorkflowClientTests.cs b/services/domain/Big.Tests/FlowableWorkflowClientTests.cs
index d852e11..b67d9d7 100644
--- a/services/domain/Big.Tests/FlowableWorkflowClientTests.cs
+++ b/services/domain/Big.Tests/FlowableWorkflowClientTests.cs
@@ -24,7 +24,7 @@ public class FlowableWorkflowClientTests
         var client = Client(capture.Responds(HttpStatusCode.Created, """{"id":"pi-1"}"""));
         var rid = RegistrationId.New();
 
-        var pid = await client.StartRegistrationProcessAsync(rid);
+        var pid = await client.StartRegistrationProcessAsync(rid, DiplomaOrigin.Binnenlands);
 
         Assert.Equal("pi-1", pid);
         Assert.Equal(HttpMethod.Post, capture.Seen!.Method);
@@ -38,6 +38,22 @@ public class FlowableWorkflowClientTests
         Assert.Contains($"\"value\":\"{rid}\"", capture.Body);
     }
 
+    [Theory]
+    [InlineData(DiplomaOrigin.Binnenlands, "Binnenlands")]
+    [InlineData(DiplomaOrigin.Buitenlands, "Buitenlands")]
+    public async Task Start_posts_the_diploma_origin_as_a_process_variable(DiplomaOrigin origin, string expected)
+    {
+        // The diploma origin rides along as a start variable so the workflow's DMN can route foreign
+        // diplomas through CBGV-advies (S-13, ADR-0016).
+        var capture = new RequestCapture();
+        var client = Client(capture.Responds(HttpStatusCode.Created, """{"id":"pi-1"}"""));
+
+        await client.StartRegistrationProcessAsync(RegistrationId.New(), origin);
+
+        Assert.Contains("\"name\":\"diplomaOrigin\"", capture.Body);
+        Assert.Contains($"\"value\":\"{expected}\"", capture.Body);
+    }
+
     [Fact]
     public async Task Start_uses_the_configured_worker_credentials_and_defaults()
     {
@@ -125,7 +141,7 @@ public class FlowableWorkflowClientTests
         var client = Client(capture.Responds(HttpStatusCode.InternalServerError));
 
         await Assert.ThrowsAsync<HttpRequestException>(
-            () => client.StartRegistrationProcessAsync(RegistrationId.New()));
+            () => client.StartRegistrationProcessAsync(RegistrationId.New(), DiplomaOrigin.Binnenlands));
     }
 
     [Fact]
@@ -135,7 +151,7 @@ public class FlowableWorkflowClientTests
         var client = Client(capture.Responds(HttpStatusCode.Created, "null"));
 
         var ex = await Assert.ThrowsAsync<InvalidOperationException>(
-            () => client.StartRegistrationProcessAsync(RegistrationId.New()));
+            () => client.StartRegistrationProcessAsync(RegistrationId.New(), DiplomaOrigin.Binnenlands));
         Assert.Contains("empty process-instance", ex.Message);
     }
 
diff --git a/tests/acceptance/Support/InMemoryDomainPorts.cs b/tests/acceptance/Support/InMemoryDomainPorts.cs
index 4926b21..af07de0 100644
--- a/tests/acceptance/Support/InMemoryDomainPorts.cs
+++ b/tests/acceptance/Support/InMemoryDomainPorts.cs
@@ -12,11 +12,14 @@ public sealed class InMemoryWorkflowClient : IWorkflowClient
     public const string StartedProcessInstanceId = "proc-acc-1";
 
     public RegistrationId? StartedFor { get; private set; }
+    public DiplomaOrigin? StartedWithOrigin { get; private set; }
     public string? WithdrawnProcessInstanceId { get; private set; }
 
-    public Task<string> StartRegistrationProcessAsync(RegistrationId registrationId, CancellationToken ct = default)
+    public Task<string> StartRegistrationProcessAsync(
+        RegistrationId registrationId, DiplomaOrigin diplomaOrigin, CancellationToken ct = default)
     {
         StartedFor = registrationId;
+        StartedWithOrigin = diplomaOrigin;
         return Task.FromResult(StartedProcessInstanceId);
     }