diff --git a/main.py b/main.py
index 101ff3b..2891928 100755
--- a/main.py
+++ b/main.py
@@ -1,11 +1,17 @@
 import datetime
 
+from caldav.lib.error import NotFoundError
+from caldav.objects import Todo
 from yaml import load, FullLoader
+import icalendar
 from icalendar.parser import Contentlines, Contentline
 from dateutil.rrule import rrule, FREQNAMES
 import caldav
 
 
+APP_ID = 'CaldavRecurringTask'
+
+
 class Task:
     def __init__(self, reference_date, name, data):
         self.ref_date = reference_date
@@ -14,20 +20,22 @@ class Task:
         self.date_begin = rrule(count=1, dtstart=reference_date, **data['start'])[0]
         self.date_end = self.date_begin + datetime.timedelta(microseconds=-1, **data['duration'])
 
+        self.uid = f"{APP_ID}-{self.name}-{self.date_begin.strftime('%Y%m%d')}"
+
+
         self.title = data['title']
         self.body = data['body']
         self.priority = data['priority']
 
     def to_ical(self):
         current_dtstamp = datetime.datetime.now().strftime('%Y%m%dT%H%M%SZ')
-        uid = f"CaldavRecurringTask-{self.name}-{self.date_end.strftime('%Y%m%d')}"
         c = Contentlines([
             Contentline('BEGIN:VCALENDAR'),
             Contentline('VERSION:2.0'),
             Contentline('PRODID:-//DorfsvaldNet//CaldavRecuringTaskClient//FR'),
             Contentline('BEGIN:VTODO'),
             Contentline(f'DTSTAMP:{current_dtstamp}'),
-            Contentline(f'UID:{uid}'),
+            Contentline(f'UID:{self.uid}'),
             Contentline(f'CREATED:{current_dtstamp}'),
             Contentline(f'LAST-MODIFIED:{current_dtstamp}'),
             Contentline(f'SEQUENCE:{"4"}'),
@@ -58,8 +66,16 @@ class Client:
         if self.calendar is None:
             raise LookupError('No calendar named "{}" found'.format(calendar_name))
 
-    def add_event(self, new_task):
-        self.calendar.add_event(new_task.to_ical())
+    def add_todo(self, new_task):
+        self.calendar.add_todo(new_task.to_ical())
+
+    def get_todo_by_uid(self, uid):
+        try:
+            todo = self.calendar.todo_by_uid(uid)
+            # todo.percent_complete = todo.icalendar_component['PERCENT-COMPLETE']
+            return todo
+        except NotFoundError:
+            return False
 
 
 if __name__ == "__main__":
@@ -79,7 +95,15 @@ if __name__ == "__main__":
     if task_list:
         server = conf['dav_server']
         client = Client(server['url'], server['user'], server['pass'], server['calendar'])
+        previous_tasks = client.todos(include_completed=True)
         for task in task_list:
-            client.add_event(task)
+            if not client.get_todo_by_uid(task.uid):
+                # Removing previous completed tasks
+                for t in previous_tasks:
+                    if t.icalendar_component.get('uid').startswith(f"{APP_ID}-{task.name}")\
+                            and t.icalendar_component.get('status') == 'COMPLETED':
+                        t.delete()
+
+                client.add_todo(task)
 
     print('process finished: {} tasks created'.format(len(task_list)))
diff --git a/tasks.example.yml b/tasks.example.yml
index f22c0c1..48c6cef 100644
--- a/tasks.example.yml
+++ b/tasks.example.yml
@@ -38,7 +38,7 @@ weekly_task:
     freq: WEEKLY
     byweekday: 6
   duration:
-    days: 60
+    days: 4
   title: A Weekly task
   body: This a task that is created once a week and starts on the last day of the week
   priority: 1
@@ -59,6 +59,6 @@ another_yearly_task:
     byweekno: 4
   duration:
     days: 60
-  title: A Yearly task
+  title: Another Yearly task
   body: This a task that is created once a year, on the fourth week of the year
   priority: 1