CLAIMING A DISCARD WHEN PLAYING A CONCEALED HAND (Article 22)

Commentary: The right margin of each panel on an American mah jongg card has an “X” or a “C” for each hand. The “X” means a player can claim a discard at any time to complete an exposure (i.e., meld). The “C” means the hand must remain concealed until it is ready to win, and if another player discards the winning tile, the player can claim it and declare mah jongg.

If a player has multiple exposures that indicate they are playing a concealed hand, another player should disqualify them from the game, and all the tiles should be returned to the sloped part of their rack.

Question from a player:  If you are playing a concealed hand, can you call for the 14th tile if it results in mah jongg? 
 
Answer from the NMJL:  The 14th tile may be thrown by another player or picked by the player who is set for Mah Jongg, whether playing an exposed or concealed hand. Mah Jongg is then declared and verified and the game ends

Source:  Mah Jongg Made Easy (2024 page 15, paragraph 6)

Other answers from the NMJL:

“Calling a tile for mah jongg is the only time you may pick up a discard when playing a concealed hand.”  

Sources for other answers:  National Mah Jongg League Bulletin Q&A (2015)