The following rules can be considered optional.
In Japanese rules it is customary to apply a rule according to which a player is prohibited to go out on a discard, which he has missed during the very same turn.
E.g., if player A is calling Bamboo 3 to go out, and player B discards Bamboo 3, and player A does not claim it, he may not claim and go out on Bamboo 3, if it is discarded by player C or D on the same turn. Player A must make a discard before being able to claim a missed discard again.
Note however that there are no restrictions on going out self-drawn on a missed discard, and that a player can claim a missed discard, if he does not go out on that tile.
The rule of Sacred discard is common in modern Japanese Mah Jong, but seldom used in classically oriented games. If the rule is used, it is normally used in its mildest form, according to which a player is prohibited from going out on a discard that is identical with his last discard.
Several different versions of Sacred discard rule are used in Japanese Mah Jong. A more restricting version extends the rule to cover the whole deal and prohibits a player to go out on a discard that is identical with any tile a player has discarded during the deal (including ones that have been claimed by others). A still more restricting version is called 1-4-7 rule, which prohibits a player to go out on a discard that completes a set that a player's sacred discard (any tile he has discarded during the deal) would complete. The most restrictive version of the rule, called absolute, prohibits a player to go out on any discard (that is, not only discards that are identical with a sacred discard, but any discard), if he has amongst his discards a tile that would complete his current hand into a structurally legal winning hand (a minimum point requirement is ignored, when this state is examined).
Some rules also allow a player to declare "Sacred discard". This informs other players that a player has a sacred discard (though the actual tile that is sacred is not displayed) and accordingly all restrictions related to sacred discard are abolished.
Modern Japanese rules often specify an extra payment for winning a dealer's extra hand. Sometimes this rule is also used in classically oriented games, but in this case the bonus is normally given only for East (dealer) for his successive wins (the modern rules often give the bonus to any winner, not just East).
The rule works so that East places a 100 point stick on the table on each successive time he acts as a dealer. This is a marker that indicates a sum each loser must pay to the winner of the deal. On the first extra hand (that is, the second time in a row the same player acts as a dealer) each loser pays 100 points to the winner of the deal (total being 300 points), on second extra hand the sum is 200 points (total being 600 points), etc.
If the winner goes out on a discard, the specified sum (i.e., 300 point on the first extra hand, 600 points on the second, etc.) is paid alone by the discarder.
Sometimes rules allow payments after a draw for player who have calling hands.
Normally a total of 600 points (in modern rules 3,000 points) is paid by non-calling players to players with a calling hand. Accordingly, if there is only one player who has a calling hand, each loser pays 200 points to him. If there are two players with a calling hand, each of the two losers pays 300 points to the two calling players. If there are three calling players, the non-calling player pays each calling player 200 points.
Often the Japanese rules specify certain conditions for a “dead hand”. In these situations an abortive draw is declared, the current deal is abandoned and a new one is started. The deal never passes as a result of an abandoned deal (even if the rules specify that the deal passes after a draw).
The following cases are sometimes acknowledged as situations in which a draw can be declared:
The etiquette for correct drawing and claiming of tiles may vary, as may the consequences for violating the etiquette. Basically the irregularities which have no effect on other players should have no consequences in friendly games. To avoid confusion, the players should agree on the etiquette and penalties before beginning the game.
In the following some common practices are listed:
Players sometimes agree on applying insurance penalties for irresponsible discards, that is, for dangerous discards that let another player go out on a big hand (this is often called "letting off a canon").
Insurance penalties are normally applied for the following hands:
Note that letting another player rob a Kong that involves a dangerous tile is considered the same as discarding a dangerous tile, and accordingly penalized in the same way.
Claiming a dangerous discard for a Kong does not result in applying insurance penalties (since in this case a player already had that dangerous set completed as a concealed Pung – promoting this set into a melded Kong does not necessarily bring the hand any closer to winning).
A player who is liable for "letting off a canon" must pay for all losers (that is, not only for himself, but also for the other two players). Note that in Japanese rules the insurance penalties are meaningful only in context of self-drawn winning hands, as a discarder always pays for all losers, anyway.