diff --git a/libcutils/include/cutils/multiuser.h b/libcutils/include/cutils/multiuser.h
index 9a2305c..4911c48 100644
--- a/libcutils/include/cutils/multiuser.h
+++ b/libcutils/include/cutils/multiuser.h
@@ -30,6 +30,7 @@
 extern appid_t multiuser_get_app_id(uid_t uid);
 
 extern uid_t multiuser_get_uid(userid_t user_id, appid_t app_id);
+extern uid_t multiuser_get_supplemental_uid(userid_t user_id, appid_t app_id);
 
 extern gid_t multiuser_get_cache_gid(userid_t user_id, appid_t app_id);
 extern gid_t multiuser_get_ext_gid(userid_t user_id, appid_t app_id);
diff --git a/libcutils/include/private/android_filesystem_config.h b/libcutils/include/private/android_filesystem_config.h
index 8e6b81c..155d3f5 100644
--- a/libcutils/include/private/android_filesystem_config.h
+++ b/libcutils/include/private/android_filesystem_config.h
@@ -210,6 +210,10 @@
  */
 #define AID_OVERFLOWUID 65534 /* unmapped user in the user namespace */
 
+/* use the ranges below to determine whether a process is supplemental */
+#define AID_SUPPLEMENTAL_PROCESS_START 20000 /* start of uids allocated to supplemental process */
+#define AID_SUPPLEMENTAL_PROCESS_END 29999   /* end of uids allocated to supplemental process */
+
 /* use the ranges below to determine whether a process is isolated */
 #define AID_ISOLATED_START 90000 /* start of uids for fully isolated sandboxed processes */
 #define AID_ISOLATED_END 99999   /* end of uids for fully isolated sandboxed processes */
diff --git a/libcutils/multiuser.cpp b/libcutils/multiuser.cpp
index 0fd3d0c..76ae4ce 100644
--- a/libcutils/multiuser.cpp
+++ b/libcutils/multiuser.cpp
@@ -29,6 +29,15 @@
     return (user_id * AID_USER_OFFSET) + (app_id % AID_USER_OFFSET);
 }
 
+uid_t multiuser_get_supplemental_uid(userid_t user_id, appid_t app_id) {
+    int supplementalProcessOffset = AID_SUPPLEMENTAL_PROCESS_START - AID_APP_START;
+    if (app_id >= AID_APP_START && app_id <= AID_APP_END) {
+        return (user_id * AID_USER_OFFSET) + (app_id % AID_USER_OFFSET) + supplementalProcessOffset;
+    } else {
+        return -1;
+    }
+}
+
 gid_t multiuser_get_cache_gid(userid_t user_id, appid_t app_id) {
     if (app_id >= AID_APP_START && app_id <= AID_APP_END) {
         return multiuser_get_uid(user_id, (app_id - AID_APP_START) + AID_CACHE_GID_START);
diff --git a/libcutils/multiuser_test.cpp b/libcutils/multiuser_test.cpp
index 4b0fd13..68270de 100644
--- a/libcutils/multiuser_test.cpp
+++ b/libcutils/multiuser_test.cpp
@@ -18,6 +18,7 @@
 #include <gtest/gtest.h>
 
 static constexpr auto ERR_GID = static_cast<gid_t>(-1);
+static constexpr auto ERR_UID = static_cast<uid_t>(-1);
 
 TEST(MultiuserTest, TestMerge) {
     EXPECT_EQ(0U, multiuser_get_uid(0, 0));
@@ -30,6 +31,22 @@
     EXPECT_EQ(1050000U, multiuser_get_uid(10, 50000));
 }
 
+TEST(MultiuserTest, TestSupplementalUid) {
+    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(0, 0));
+    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(0, 1000));
+    EXPECT_EQ(20000U, multiuser_get_supplemental_uid(0, 10000));
+    EXPECT_EQ(25000U, multiuser_get_supplemental_uid(0, 15000));
+    EXPECT_EQ(29999U, multiuser_get_supplemental_uid(0, 19999));
+    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(0, 50000));
+
+    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(10, 0));
+    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(10, 1000));
+    EXPECT_EQ(1020000U, multiuser_get_supplemental_uid(10, 10000));
+    EXPECT_EQ(1025000U, multiuser_get_supplemental_uid(10, 15000));
+    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(10, 20000));
+    EXPECT_EQ(ERR_UID, multiuser_get_supplemental_uid(10, 50000));
+}
+
 TEST(MultiuserTest, TestSplitUser) {
     EXPECT_EQ(0U, multiuser_get_user_id(0));
     EXPECT_EQ(0U, multiuser_get_user_id(1000));