diff --git a/SilKit/IntegrationTests/ITest_AsyncSimTask.cpp b/SilKit/IntegrationTests/ITest_AsyncSimTask.cpp
index e97fb04e0..589293df2 100644
--- a/SilKit/IntegrationTests/ITest_AsyncSimTask.cpp
+++ b/SilKit/IntegrationTests/ITest_AsyncSimTask.cpp
@@ -362,4 +362,126 @@ TEST(ITest_AsyncSimTask, test_async_simtask_other_simulation_steps_completed_han
     cd.AssertTimestampsAlwaysOutsideStep(stepLastOpen);
 }
 
+// Verify timestamp behavior from the synchronized participant perspective:
+// - Sync sender: outgoing event carries virtual send time.
+// - Async sender: outgoing events will have an invalid timestamp
+// - Sync receiver: incoming event from async or sync sender is timestamped with sync receive time.
+// - Async receiver: incoming event from async or sync sender keeps the timestamp (async sender: invalid timestamp, sync sender: send time)
+TEST(ITest_AsyncSimTask, test_timestamp_handling)
+{
+    SimTestHarness testHarness({"Sync"}, "silkit://localhost:0", false, false, {"Async", "Async2"});
+
+    const auto dataSpecSyncToAsync = SilKit::Services::PubSub::PubSubSpec{"TopicSyncToAsync", "A"};
+    const auto dataSpecAsyncToSync = SilKit::Services::PubSub::PubSubSpec{"TopicAsyncToSync", "A"};
+    const auto dataSpecAsyncToAsync = SilKit::Services::PubSub::PubSubSpec{"TopicAsyncToAsync", "A"};
+    const auto dataSpecSyncToSync = SilKit::Services::PubSub::PubSubSpec{"TopicSyncToSync", "A"};
+
+    auto* syncParticipant = testHarness.GetParticipant("Sync");
+    auto* asyncParticipant = testHarness.GetParticipant("Async");
+    auto* async2Participant = testHarness.GetParticipant("Async2");
+
+    auto* syncLifecycleService = syncParticipant->GetOrCreateLifecycleService();
+    auto* asyncLifecycleService = asyncParticipant->GetOrCreateLifecycleService();
+    auto* async2LifecycleService = async2Participant->GetOrCreateLifecycleService();
+    auto* syncTimeSyncService = syncParticipant->GetOrCreateTimeSyncService();
+
+    auto* syncPublisher = syncParticipant->Participant()->CreateDataPublisher("SyncPub", dataSpecSyncToAsync);
+    auto* asyncPublisher = asyncParticipant->Participant()->CreateDataPublisher("AsyncPub", dataSpecAsyncToSync);
+    auto* asyncPublisherToAsync2 = asyncParticipant->Participant()->CreateDataPublisher("AsyncPubToAsync2", dataSpecAsyncToAsync);
+    auto* syncPublisherToSync = syncParticipant->Participant()->CreateDataPublisher("SyncPubToSync", dataSpecSyncToSync);
+
+    std::atomic<std::chrono::nanoseconds::rep> syncSendTimeNs{std::chrono::nanoseconds::min().count()};
+    std::atomic<std::chrono::nanoseconds::rep> syncCurrentStepNs{std::chrono::nanoseconds::min().count()};
+    std::atomic<bool> syncToAsyncReceived{false};
+    std::atomic<bool> asyncToSyncReceived{false};
+    std::atomic<bool> asyncToAsyncReceived{false};
+    std::atomic<bool> syncToSyncReceived{false};
+    std::atomic<bool> syncSent{false};
+
+    asyncParticipant->Participant()->CreateDataSubscriber(
+        "AsyncSub", dataSpecSyncToAsync,
+        [asyncPublisher, asyncPublisherToAsync2, &syncSendTimeNs,
+         &syncToAsyncReceived](SilKit::Services::PubSub::IDataSubscriber* /*subscriber*/,
+                               const SilKit::Services::PubSub::DataMessageEvent& dataMessageEvent) {
+        const auto expectedTimestamp = std::chrono::nanoseconds{syncSendTimeNs.load()};
+        EXPECT_NE(expectedTimestamp, std::chrono::nanoseconds::min());
+        EXPECT_EQ(dataMessageEvent.timestamp, expectedTimestamp);
+
+        if (!syncToAsyncReceived.exchange(true))
+        {
+            asyncPublisher->Publish(std::vector<uint8_t>{0xA5});
+            asyncPublisherToAsync2->Publish(std::vector<uint8_t>{0x3C});
+        }
+    });
+
+    syncParticipant->Participant()->CreateDataSubscriber(
+        "SyncSub", dataSpecAsyncToSync,
+        [&syncCurrentStepNs, &asyncToSyncReceived](SilKit::Services::PubSub::IDataSubscriber* /*subscriber*/,
+                                                   const SilKit::Services::PubSub::DataMessageEvent& dataMessageEvent) {
+        const auto currentStep = std::chrono::nanoseconds{syncCurrentStepNs.load()};
+
+        EXPECT_TRUE((dataMessageEvent.timestamp == currentStep) || (dataMessageEvent.timestamp == currentStep + 1ms)
+                    || (dataMessageEvent.timestamp == currentStep - 1ms))
+            << "Incoming async message should be timestamped with the sync receiver time (+/-1ms tolerance).";
+        asyncToSyncReceived = true;
+    });
+
+    syncParticipant->Participant()->CreateDataSubscriber(
+        "SyncSubFromSync", dataSpecSyncToSync,
+        [&syncCurrentStepNs, &syncToSyncReceived](SilKit::Services::PubSub::IDataSubscriber* /*subscriber*/,
+                                                  const SilKit::Services::PubSub::DataMessageEvent& dataMessageEvent) {
+        const auto currentStep = std::chrono::nanoseconds{syncCurrentStepNs.load()};
+
+        EXPECT_TRUE((dataMessageEvent.timestamp == currentStep) || (dataMessageEvent.timestamp == currentStep + 1ms)
+                    || (dataMessageEvent.timestamp == currentStep - 1ms))
+            << "Incoming sync message should be timestamped with the sync receiver time (+/-1ms tolerance).";
+        syncToSyncReceived = true;
+    });
+
+    async2Participant->Participant()->CreateDataSubscriber(
+        "Async2Sub", dataSpecAsyncToAsync,
+        [&asyncToAsyncReceived](SilKit::Services::PubSub::IDataSubscriber* /*subscriber*/,
+                                const SilKit::Services::PubSub::DataMessageEvent& dataMessageEvent) {
+        EXPECT_EQ(dataMessageEvent.timestamp, std::chrono::nanoseconds::min())
+            << "Outgoing async messages must have invalid timestamps.";
+        asyncToAsyncReceived = true;
+    });
+
+    syncTimeSyncService->SetSimulationStepHandler(
+        [syncLifecycleService, asyncLifecycleService, async2LifecycleService, syncPublisher, syncPublisherToSync,
+         &syncSendTimeNs, &syncCurrentStepNs, &syncSent, &syncToAsyncReceived, &asyncToSyncReceived,
+         &asyncToAsyncReceived, &syncToSyncReceived](std::chrono::nanoseconds now,
+                                                     std::chrono::nanoseconds /*duration*/) {
+        syncCurrentStepNs = now.count();
+
+        if (!syncSent && now >= 1ms)
+        {
+            syncSendTimeNs = now.count();
+            syncPublisher->Publish(std::vector<uint8_t>{0x5A});
+            syncPublisherToSync->Publish(std::vector<uint8_t>{0xC3});
+            syncSent = true;
+        }
+
+        if (syncToAsyncReceived && asyncToSyncReceived && asyncToAsyncReceived && syncToSyncReceived)
+        {
+            asyncLifecycleService->Stop("Timestamp handling verified");
+            async2LifecycleService->Stop("Timestamp handling verified");
+            syncLifecycleService->Stop("Timestamp handling verified");
+        }
+        else if (now >= 20ms)
+        {
+            asyncLifecycleService->Stop("Timestamp handling timed out");
+            async2LifecycleService->Stop("Timestamp handling timed out");
+            syncLifecycleService->Stop("Timestamp handling timed out");
+        }
+    },
+        1ms);
+
+    ASSERT_TRUE(testHarness.Run(5s));
+    ASSERT_TRUE(syncToAsyncReceived.load());
+    ASSERT_TRUE(asyncToSyncReceived.load());
+    ASSERT_TRUE(asyncToAsyncReceived.load());
+    ASSERT_TRUE(syncToSyncReceived.load());
+}
+
 } // anonymous namespace