diff --git a/Endpoint/Controllers/V1/GroupController.cs b/Endpoint/Controllers/V1/GroupController.cs
index 6197047..fe6f079 100644
--- a/Endpoint/Controllers/V1/GroupController.cs
+++ b/Endpoint/Controllers/V1/GroupController.cs
@@ -26,7 +26,7 @@ public class GroupController(IMediator mediator) : BaseController
         // Convert a two-digit year to a four-digit one
         yearOfGroup += current.Year / 100 * 100;
 
-        return current.Year - yearOfGroup + (current.Month < 9 ? 0 : 1);
+        return current.Year - yearOfGroup + (current.Month < 8 ? 0 : 1);
     }
 
     /// <summary>