diff --git a/apps/registration/models.py b/apps/registration/models.py
index 3e12fce..3a603f8 100644
--- a/apps/registration/models.py
+++ b/apps/registration/models.py
@@ -159,7 +159,13 @@ class ParticipantRegistration(Registration):
 
     @property
     def under_18(self):
-        return (timezone.now().date() - self.birth_date).days < 18 * 365.24
+        important_date = timezone.now().date()
+        if self.team and self.team.participation.tournament:
+            important_date = self.team.participation.tournament.date_start
+            if self.team.participation.final:
+                from participation.models import Tournament
+                important_date = Tournament.final_tournament().date_start
+        return (important_date - self.birth_date).days < 18 * 365.24
 
     @property
     def type(self):  # pragma: no cover