diff --git a/src/Form/Service/ParticipantFieldOptionsProvider.php b/src/Form/Service/ParticipantFieldOptionsProvider.php
index e62376e..8add401 100644
--- a/src/Form/Service/ParticipantFieldOptionsProvider.php
+++ b/src/Form/Service/ParticipantFieldOptionsProvider.php
@@ -153,8 +153,9 @@ class ParticipantFieldOptionsProvider extends AbstractFieldOptionsProvider
 
                 $attributes = [];
 
-                // Make readonly for mandatory services (pre-selection handled by service layer)
+                // Make readonly and checked for mandatory services (pre-selection handled by service layer)
                 if (true === $service->mandatory) {
+                    $attributes['checked'] = true;
                     $attributes['readonly'] = true;
                     $attributes['class'] = 'text-pink';
                     $attributes['data-tooltip'] = 'Diese Leistung ist nicht abwählbar';