When a player calls a discarded tile and picks it up, that tile must be placed on top of the rack (the flat surface)—not directly into the sloped portion of the rack.

This practice ensures that all players can clearly see and confirm that the correct tile was called before it is added to the hand. It promotes fairness and transparency at the table and helps maintain the integrity of the game.

Placing the tile on top of the rack also helps prevent potential mistakes—or even the appearance of impropriety. If a tile were placed directly into the rack, it could allow a player to inadvertently or intentionally pick up a different tile than the one discarded without the other players being able to verify it.

At this time, there is no official penalty for placing the tile directly into the rack. However, the National Mah Jongg League does state that the tile must be placed on top of the rack.

As such, individual groups or tournaments may choose to enforce this standard with a penalty at their discretion.