diff --git a/sdk/include/psdk/msctfmonitorapi.h b/sdk/include/psdk/msctfmonitorapi.h
new file mode 100644
index 00000000000..994e140e30b
--- /dev/null
+++ b/sdk/include/psdk/msctfmonitorapi.h
@@ -0,0 +1,20 @@
+/*
+ * PROJECT:     ReactOS PSDK
+ * LICENSE:     LGPL-2.0-or-later (https://spdx.org/licenses/LGPL-2.0-or-later)
+ * PURPOSE:     Definitions for the MS CTF monitor
+ * COPYRIGHT:   Copyright 2026 Katayama Hirofumi MZ <katayama.hirofumi.mz@gmail.com>
+ */
+
+#pragma once
+
+#define ILMCM_CHECKLAYOUTANDTIPENABLED 0x1
+#define ILMCM_LANGUAGEBAROFF 0x2
+
+EXTERN_C HRESULT WINAPI InitLocalMsCtfMonitor(_In_ DWORD dwFlags);
+EXTERN_C HRESULT WINAPI UninitLocalMsCtfMonitor(VOID);
+
+#define DCM_FLAGS_TASKENG 0x1
+#define DCM_FLAGS_CTFMON 0x2
+#define DCM_FLAGS_LOCALTHREADTSF 0x4
+
+EXTERN_C BOOL WINAPI DoMsCtfMonitor(_In_ DWORD dwFlags, _In_ HANDLE hEventForServiceStop);