Japanese Mahjong Scoring Rules - Chombo

Under the rule of chombo (チョンボ, 錯和 or 冲和), a player pays a penalty of the same amount as mangan to other players in most rules. A non-dealer pays 4,000 to East and 2,000 to the other two players, while a dealer pays 4,000 to each. Chombo occurs for any of the following:

• Invalidly claiming a winning hand
• Winning on a discard under the situation of sacred discard (furiten)
• False rīchi, that is, rīchi with a hand that is not in the state of tenpai
• Closed kan after rīchi if the kan changes the player's waits
• Having more tiles than allowed (depending on the rules)
• Crashing the wall so that it cannot be recovered

Note that false rīchi are caught only after draws or winning declarations by players who declared the rīchi.

Any rīchi bets are returned to the players after the end of a chombo hand.