diff --git a/mtapi_c/include/embb/mtapi/c/mtapi.h b/mtapi_c/include/embb/mtapi/c/mtapi.h
index 38e9341..4ebadba 100644
--- a/mtapi_c/include/embb/mtapi/c/mtapi.h
+++ b/mtapi_c/include/embb/mtapi/c/mtapi.h
@@ -557,6 +557,17 @@ enum mtapi_node_attributes_enum {
 #define MTAPI_NODE_TYPE_SMP 1
 #define MTAPI_NODE_TYPE_DSP 2
 
+/**
+ * Task handle type.
+ * \memberof mtapi_task_hndl_struct
+ */
+typedef struct mtapi_task_hndl_struct mtapi_task_hndl_t;
+
+/** task completion callback */
+typedef void(*mtapi_task_complete_function_t)(
+  MTAPI_IN mtapi_task_hndl_t task,
+  MTAPI_OUT mtapi_status_t* status);
+
 /** task attributes */
 enum mtapi_task_attributes_enum {
   MTAPI_TASK_DETACHED,                 /**< task is detached, i.e., the runtime
@@ -574,7 +585,9 @@ enum mtapi_task_attributes_enum {
                                             executed n times, if possible in
                                             parallel */
   MTAPI_TASK_PRIORITY,
-  MTAPI_TASK_AFFINITY
+  MTAPI_TASK_AFFINITY,
+  MTAPI_TASK_USER_DATA,
+  MTAPI_TASK_COMPLETE_FUNCTION
 };
 /** size of the \a MTAPI_TASK_DETACHED attribute */
 #define MTAPI_TASK_DETACHED_SIZE sizeof(mtapi_boolean_t)
@@ -671,6 +684,10 @@ struct mtapi_task_attributes_struct {
   mtapi_uint_t num_instances;          /**< stores MTAPI_TASK_INSTANCES */
   mtapi_uint_t priority;               /**< stores MTAPI_TASK_PRIORITY */
   mtapi_affinity_t affinity;           /**< stores MTAPI_TASK_AFFINITY */
+  void * user_data;                    /**< stores MTAPI_TASK_USER_DATA */
+  mtapi_task_complete_function_t
+    complete_func;                     /**< stores
+                                            MTAPI_TASK_COMPLETE_FUNCTION */
 };
 
 /**
@@ -869,11 +886,8 @@ struct mtapi_task_hndl_struct {
   mtapi_task_id_t id;                  /**< pool index of this handle */
 };
 
-/**
- * Task handle type.
- * \memberof mtapi_task_hndl_struct
- */
-typedef struct mtapi_task_hndl_struct mtapi_task_hndl_t;
+// was forward declared
+//typedef struct mtapi_task_hndl_struct mtapi_task_hndl_t;
 
 
 /* ---- BASIC CONSTANTS ---------------------------------------------------- */
diff --git a/mtapi_c/src/embb_mtapi_action_t.c b/mtapi_c/src/embb_mtapi_action_t.c
index b21ba35..f79f03d 100644
--- a/mtapi_c/src/embb_mtapi_action_t.c
+++ b/mtapi_c/src/embb_mtapi_action_t.c
@@ -56,6 +56,7 @@ void embb_mtapi_action_initialize(embb_mtapi_action_t* that) {
   that->enabled = MTAPI_FALSE;
   that->node_local_data = NULL;
   that->node_local_data_size = 0;
+  that->plugin_data = MTAPI_NULL;
   embb_atomic_store_int(&that->num_tasks, 0);
 }
 
diff --git a/mtapi_c/src/embb_mtapi_scheduler_t.c b/mtapi_c/src/embb_mtapi_scheduler_t.c
index fe7499e..cbcf914 100644
--- a/mtapi_c/src/embb_mtapi_scheduler_t.c
+++ b/mtapi_c/src/embb_mtapi_scheduler_t.c
@@ -345,6 +345,11 @@ int embb_mtapi_scheduler_worker(void * arg) {
         /* do nothing, although this is an error */
         break;
       }
+
+      /* issue task complete callback if set */
+      if (MTAPI_NULL != task->attributes.complete_func) {
+        task->attributes.complete_func(task->handle, MTAPI_NULL);
+      }
     } else if (counter < 1024) {
       /* spin and yield for a while before going to sleep */
       embb_thread_yield();
diff --git a/mtapi_c/src/mtapi_task_attributes_t.c b/mtapi_c/src/mtapi_task_attributes_t.c
index 718181f..ee3e166 100644
--- a/mtapi_c/src/mtapi_task_attributes_t.c
+++ b/mtapi_c/src/mtapi_task_attributes_t.c
@@ -25,6 +25,7 @@
  */
 
 #include <assert.h>
+#include <string.h>
 
 #include <embb/mtapi/c/mtapi.h>
 
@@ -46,6 +47,7 @@ void mtapi_taskattr_init(
     attributes->num_instances = 1;
     attributes->is_detached = MTAPI_FALSE;
     attributes->priority = 0;
+    attributes->complete_func = MTAPI_NULL;
     mtapi_affinity_init(&attributes->affinity, MTAPI_TRUE, &local_status);
   } else {
     local_status = MTAPI_ERR_PARAMETER;
@@ -90,6 +92,16 @@ void mtapi_taskattr_set(
           &attributes->affinity, attribute, attribute_size);
         break;
 
+      case MTAPI_TASK_USER_DATA:
+        attributes->user_data = (void*)attribute;
+        local_status = MTAPI_SUCCESS;
+        break;
+
+      case MTAPI_TASK_COMPLETE_FUNCTION:
+        memcpy(&attributes->complete_func, &attribute, sizeof(void*));
+        local_status = MTAPI_SUCCESS;
+        break;
+
       default:
         /* attribute unknown */
         local_status = MTAPI_ERR_ATTR_NUM;