diff --git a/backend/src/main/java/core/entities/timemanager/TaskSerieItem.java b/backend/src/main/java/core/entities/timemanager/TaskSerieItem.java
index f5d40fc..46728fa 100644
--- a/backend/src/main/java/core/entities/timemanager/TaskSerieItem.java
+++ b/backend/src/main/java/core/entities/timemanager/TaskSerieItem.java
@@ -10,11 +10,11 @@ public class TaskSerieItem {
     @GeneratedValue(strategy = GenerationType.AUTO)
     private long itemID;
 
-    @ManyToOne()
+    @ManyToOne
     @JoinColumn(referencedColumnName = "taskSerieID")
     private TaskSerie taskSerie;
 
-    @OneToOne
+    @OneToOne(cascade = CascadeType.ALL)
     @JoinColumn(name = "task_id")
     private Task task;
 
diff --git a/backend/src/main/java/core/services/TaskSeriesService.java b/backend/src/main/java/core/services/TaskSeriesService.java
index e0e1a9a..efac5cb 100644
--- a/backend/src/main/java/core/services/TaskSeriesService.java
+++ b/backend/src/main/java/core/services/TaskSeriesService.java
@@ -69,7 +69,7 @@ public class TaskSeriesService {
         TaskSerie taskSerie = task.getTaskSerieItem().getTaskSerie();
         task.setTaskSerieItem(null);
         taskSerieItemRepository.delete(item);
-        if(taskSerie.getTasks().size() == 1) {
+        if(taskSerie.getTasks().size() <= 1) {
             taskSeriesRepository.delete(taskSerie);
         }
     }