diff --git a/README.md b/README.md
index 8194122..8d289a1 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,7 @@
 - [] remove key from src/rest/admin/rss.rs (line 8); at least before putting code somewhere public
 - [] add `trip_type` (id, name, desc, question) with a FK to `trip_details`
 - [] add `always_show` to `planned_trips` (e.g. for wanderfahrten)
+- [] exactly same time -> deny registration
 
 # Nice to have
 - [] automatically add regular planned trip