diff --git a/internal/services/task_service.go b/internal/services/task_service.go
index 5ef5fa7..9686dc0 100644
--- a/internal/services/task_service.go
+++ b/internal/services/task_service.go
@@ -490,12 +490,14 @@ func (s *TaskService) CreateCompletion(req *requests.CreateTaskCompletionRequest
 	}
 
 	// Update next_due_date and status based on frequency
-	// - If frequency is "Once" (days = nil or 0), set next_due_date to nil
+	// - If frequency is "Once" (days = nil or 0), set next_due_date to nil and status to "Completed"
 	// - If frequency is recurring, calculate next_due_date = completion_date + frequency_days
 	//   and reset status to "Pending" so task shows in correct kanban column
 	if task.Frequency == nil || task.Frequency.Days == nil || *task.Frequency.Days == 0 {
-		// One-time task - clear next_due_date since it's completed
+		// One-time task - clear next_due_date and set status to "Completed" (ID=3)
 		task.NextDueDate = nil
+		completedStatusID := uint(3)
+		task.StatusID = &completedStatusID
 	} else {
 		// Recurring task - calculate next due date from completion date + frequency
 		nextDue := completedAt.AddDate(0, 0, *task.Frequency.Days)