diff --git a/CRM/Twingle/Form/Profile.php b/CRM/Twingle/Form/Profile.php
index dc54b39..ea83455 100644
--- a/CRM/Twingle/Form/Profile.php
+++ b/CRM/Twingle/Form/Profile.php
@@ -379,6 +379,13 @@ class CRM_Twingle_Form_Profile extends CRM_Core_Form {
       FALSE, // is not required
       array('class' => 'crm-select2 huge')
     );
+    $this->add(
+        'text',
+        'membership_postprocess_call',
+        E::ts('API Call for Membership Postprocessing'),
+        FALSE
+    );
+    $this->addRule('membership_postprocess_call', E::ts("The API call must have the form 'Entity.Action'."), 'regex', '/^[A-Za-z_]+[.][A-Za-z_]+$/');
 
     $this->add(
       'text', // field type
diff --git a/CRM/Twingle/Profile.php b/CRM/Twingle/Profile.php
index 5c98333..e61f4df 100644
--- a/CRM/Twingle/Profile.php
+++ b/CRM/Twingle/Profile.php
@@ -219,6 +219,7 @@ class CRM_Twingle_Profile {
         'custom_field_mapping',
         'membership_type_id',
         'membership_type_id_recur',
+        'membership_postprocess_call',
       ),
       // Add payment methods.
       array_keys(static::paymentInstruments()),
diff --git a/api/v3/TwingleDonation/Submit.php b/api/v3/TwingleDonation/Submit.php
index 52de247..505b1fc 100644
--- a/api/v3/TwingleDonation/Submit.php
+++ b/api/v3/TwingleDonation/Submit.php
@@ -667,11 +667,51 @@ function civicrm_api3_twingle_donation_Submit($params) {
     }
     if (!empty($membership_type_id)) {
       $membership = civicrm_api3('Membership', 'create', array(
-        'contact_id' => $contact_id,
-        'membership_type_id' => $membership_type_id,
+          'contact_id'         => $contact_id,
+          'membership_type_id' => $membership_type_id,
       ));
-
       $result_values['membership'] = $membership;
+
+      // call the postprocess API
+      $postprocess_call = $profile->getAttribute('membership_postprocess_call');
+      if (!empty($postprocess_call)) {
+        list($pp_entity, $pp_action) = explode('.', $postprocess_call, 1);
+        try {
+          // gather the contribution IDs
+          $recurring_contribution_id = $contribution_id = '';
+          if (isset($mandate)) {
+            if ($mandate['type'] == 'RCUR') {
+              $recurring_contribution_id = $mandate['entity_id'];
+            } elseif ($mandate['type'] == 'OOFF') {
+              $contribution_id = $mandate['entity_id'];
+            }
+          } else {
+            if (isset($contribution_recur['id'])) {
+              $recurring_contribution_id = $contribution_recur['id'];
+            }
+            if (isset($contribution['id'])) {
+              $contribution_id = $contribution['id'];
+            }
+          }
+
+          // run the call
+          civicrm_api3($pp_entity, $pp_action, [
+              'membership_id'             => $membership['id'],
+              'contact_id'                => $contact_id,
+              'organization_id'           => isset($organisation_id) ? $organisation_id : '',
+              'contribution_id'           => $contribution_id,
+              'recurring_contribution_id' => $recurring_contribution_id,
+          ]);
+
+          // refresh membership data
+          $result_values['membership'] = civicrm_api3('Membership', 'getsingle', $membership['id']);
+
+        } catch (Exception $ex) {
+          // TODO: more error handling?
+          Civi::log()->debug("Twingle membership postprocessing call {$pp_entity}.{$pp_action} has failed: " . $ex->getMessage());
+        }
+      }
+
     }
 
     $result = civicrm_api3_create_success($result_values);
diff --git a/templates/CRM/Twingle/Form/Profile.hlp b/templates/CRM/Twingle/Form/Profile.hlp
index 81045c2..8a89223 100644
--- a/templates/CRM/Twingle/Form/Profile.hlp
+++ b/templates/CRM/Twingle/Form/Profile.hlp
@@ -38,6 +38,17 @@
     {ts domain="de.systopia.twingle"}Select which financial type to use for recurring contributions.{/ts}
 {/htxt}
 
+{htxt id='id-membership-postprocessing-call'}
+    {ts domain="de.systopia.twingle"}Some organisations have specific conventions on how a membership should be created. Since the Twingle-API can only create a "bare bone" membership object, you can enter a API Call (as 'Entity.Action') to adjust any newly created membership to your organisation's needs.{/ts}
+    {ts domain="de.systopia.twingle"}The API call would receive the following parameters:<ul>
+        <li><code>membership_id</code>: The ID of the newly created membership</li>
+        <li><code>contact_id</code>: The ID of the contact involved</li>
+        <li><code>organization_id</code>: The ID of the contact's organisation, potentially empty</li>
+        <li><code>contribution_id</code>: The ID contribution received, potentially empty</li>
+        <li><code>recurring_contribution_id</code>: The ID of the recurring contribution. If empty, this was only a one-off donation.</li>
+    </ul>{/ts}
+{/htxt}
+
 {htxt id='id-custom_field_mapping'}
     {ts domain="de.systopia.twingle"}<p>Map Twingle custom fields to CiviCRM custom fields using the following format (each assignment in a separate line):</p>
     <pre>twingle_field_1=custom_123<br />twingle_field_2=custom_789</pre>
diff --git a/templates/CRM/Twingle/Form/Profile.tpl b/templates/CRM/Twingle/Form/Profile.tpl
index 3878454..17e0c87 100644
--- a/templates/CRM/Twingle/Form/Profile.tpl
+++ b/templates/CRM/Twingle/Form/Profile.tpl
@@ -236,6 +236,27 @@
           <td class="label">{$form.membership_type_id_recur.label}</td>
           <td class="content">{$form.membership_type_id_recur.html}</td>
         </tr>
+        <tr class="crm-section twingle-postprocess-call">
+          <td class="label">
+            {$form.membership_postprocess_call.label}
+            <a
+                    onclick='
+                            CRM.help(
+                            "{ts domain="de.systopia.twingle"}Membership Postprocessing{/ts}",
+                    {literal}{
+                      "id": "id-membership-postprocessing-call",
+                      "file": "CRM\/Twingle\/Form\/Profile"
+                    }{/literal}
+                            );
+                            return false;
+                            '
+                    href="#"
+                    title="{ts domain="de.systopia.twingle"}Help{/ts}"
+                    class="helpicon"
+            ></a>
+          </td>
+          <td class="content">{$form.membership_postprocess_call.html}</td>
+        </tr>
 
         <tr class="crm-section">
           <td class="label">{$form.contribution_source.label}</td>
@@ -286,3 +307,27 @@
   </div>
 
 </div>
+
+{literal}
+<script>
+  /**
+   * Update the form fields based on whether membership creation is currently active
+   */
+  function twingle_membership_active_changed() {
+    let active = cj('#membership_type_id').val() || cj('#membership_type_id_recur').val();
+    if (active) {
+      cj('#membership_postprocess_call').parent().parent().show();
+    } else {
+      cj('#membership_postprocess_call').val(''); // empty to avoid hidden validation fail
+      cj('#membership_postprocess_call').parent().parent().hide();
+    }
+  }
+
+  // register events and run once
+  cj(document).ready(function (){
+    cj('#membership_type_id').change(twingle_membership_active_changed);
+    cj('#membership_type_id_recur').change(twingle_membership_active_changed);
+  });
+  twingle_membership_active_changed();
+</script>
+{/literal}
\ No newline at end of file