diff --git a/src/Api.php b/src/Api.php
index 53f2e93..3e49a20 100644
--- a/src/Api.php
+++ b/src/Api.php
@@ -126,14 +126,22 @@ class Api {
 
     public function putMembership(int $memberId, array $data): int
     {
-        $url = self::$url."/ica/rest/nami/zugeordnete-taetigkeiten/filtered-for-navigation/gruppierung-mitglied/mitglied/{$memberId}";
-
-        $response = $this->http()->post($url, $data);
+        if (data_get($data, 'id')) {
+            $url = self::$url."/ica/rest/nami/zugeordnete-taetigkeiten/filtered-for-navigation/gruppierung-mitglied/mitglied/{$memberId}/{$data['id']}";
+            $response = $this->http()->put($url, $data);
+        } else {
+            $url = self::$url."/ica/rest/nami/zugeordnete-taetigkeiten/filtered-for-navigation/gruppierung-mitglied/mitglied/{$memberId}";
+            $response = $this->http()->post($url, $data);
+        }
         if (data_get($response->json(), 'success') !== true) {
             $this->exception('Update failed', ['url' => $url, 'data' => $data], $response->json());
         }
 
-        return $response->json()['data'];
+        if (data_get($data, 'id')) {
+            return $response->json()['data']['id'];
+        } else {
+            return $response->json()['data'];
+        }
     }
 
     public function membershipsOf($memberId): Collection {
diff --git a/src/Member.php b/src/Member.php
index c87e893..76039f6 100644
--- a/src/Member.php
+++ b/src/Member.php
@@ -158,7 +158,19 @@ class Member extends Model {
             'gruppierungId' => $data['group_id'],
             'taetigkeitId' => $data['activity_id'],
             'untergliederungId' => $data['subactivity_id'],
-            'aktivVon' => $data['created_at']->format('Y-m-d').'T00:00:00',
+            'aktivVon' => $data['starts_at']->format('Y-m-d').'T00:00:00',
+        ]);
+    }
+
+    public function deleteMembership(int $id): int
+    {
+        $membership = $this->membership($id);
+
+        return Nami::putMembership($this->id, [
+            'gruppierungId' => $membership->group_id,
+            'aktivVon' => $membership->starts_at.'T00:00:00',
+            'aktivBis' => now()->format('Y-m-d').'T00:00:00',
+            'id' => $membership->id,
         ]);
     }