An illegal move is a move the rules of the game do not allow. A piece moved against its own rules, the player's own king stayed in or walked into check, castling broke one of its conditions.
What matters most to the arbiter is the moment the move counts as made. Under Article 7.5.1 an illegal move is completed when the player has pressed the clock. Until the clock is pressed it is not yet an offence: the move must be replayed, there is no penalty, but touch-move applies - the player must move the same piece if it has a legal move.
At amateur tournaments almost all illegal moves are one of three situations. Red marks squares the piece may not go to, a dot - where the move is allowed.
Less common:
How castling works in full - in castling in chess, with every condition on a diagram.
The 2023 Laws penalise three more actions as an illegal move. Players often do not know about them and argue with the arbiter:
| Action | Article | How it is penalised |
|---|---|---|
| Pressed the clock without making a move | 7.5.3 | penalised as an illegal move |
| Made a move with two hands and pressed the clock (castling, a capture, a promotion) | 7.5.4 | penalised as an illegal move |
| Moved a pawn to the last rank, pressed the clock, but did not put a piece down | 7.5.2 | an illegal move; the pawn is replaced by a queen of the same colour |
| Moved a piece but has not pressed the clock yet | 7.5.1 | the move is not completed: it must be corrected, but there is no penalty |
A word about two hands: castling is done with one hand - first the king, then the rook. The king with one hand and the rook with the other, then pressing the clock, is already an offence under 7.5.4 with a penalty.
The penalty works the same way but differs in size. In classical the opponent gets two extra minutes (Article 7.5.5), in rapid and blitz - one (Article A.3 of the rapid chess appendix). A second illegal move by the same player in the same game - a loss.
| Classical | Rapid (more than 10 and less than 60 minutes) | Blitz (10 minutes or less) | |
|---|---|---|---|
| First illegal move | +2 minutes to the opponent | +1 minute to the opponent | +1 minute to the opponent |
| Second illegal move by the same player in the same game | loss | loss | loss |
| …but the opponent cannot checkmate with the material left | draw | draw | draw |
| Who notices | the arbiter at any point in the game | the arbiter or the opponent - before the opponent's next move | the arbiter or the opponent - before the opponent's next move |
| The opponent has already replied | the position is restored anyway | the move stands | the move stands |
A draw instead of a loss - when the opponent does not have enough material to checkmate by any series of legal moves. For example, they have only a king left. The same logic as when a flag falls - see a fallen flag in chess.
The count runs within one game. An illegal move in round one does not "carry over" to round two: in a new game each player starts again at zero offences.
This is where classical and fast chess differ most.
There is an exception. If in rapid one arbiter supervises no more than three games, and in blitz - one, and the moves are recorded, the classical rules apply (Articles A.4 and B.2). Finals and games on demonstration boards are played this way. The tournament regulations say in advance which version applies.
Step 3 is argued about most. Article 7.5.1 refers directly to touch-move (4.3 and 4.7): played the king to e2 - now you must move the king, if it has a legal move. If that piece has no legal moves, the player is free to choose.
The time on the clock is not rolled back when the position is restored: time spent on the illegal move stays spent. Only the opponent's time changes - by the penalty minute or two.
At Vibe Chess tournaments the arbiter is not alone: the phones at the tables help. Here is what they do when an illegal move happens.
How arbiting works in the app as a whole - arbiting a chess tournament, and how the camera records a game - chessboard recognition with a camera.
So that the argument does not start in the middle of a round, put the illegal-move rule into the regulations and announce it before round one. The text can be used as it is:
For classical, replace "1 extra minute" with "2 extra minutes" and remove the sentence saying the move stands. The rest of the regulations - in blitz chess rules and rapid chess rules.
The position is restored and the opponent gets one extra minute. You must move the same piece if it has a legal move. A second illegal move in the game loses. But if the opponent has already replied and nobody claimed, the illegal move stands.
No. That was the rule until 2018. Since 1 January 2018, and under the current 2023 FIDE Laws, only a second illegal move in a game loses; the first gives the opponent a minute.
In classical - two minutes to the opponent, in rapid and blitz - one minute.
In classical - yes: the position is restored as soon as the offence is discovered. In rapid and blitz - no: you can claim only before your reply. After it the illegal move stands unless the players themselves agree to correct it.
Yes. Under Article 7.5.3 pressing the clock without a move is penalised like an illegal move: the opponent gets extra time, and a second such case in the game loses.
Stop the clock and ask the arbiter for the piece you need. If you press the clock leaving the pawn on the last rank, it is an illegal move: the pawn is replaced by a queen and the opponent gets extra time.
If the game is being recorded by a phone camera, the app notices the illegal move itself, sounds an alert and says which piece to put back. If play continued after the illegal move, recording stops at the last legal position and the game does not count towards the rating.
The Vibe Chess app is built for an evening over the board, not for online play: it keeps the sign-up list, the pairings and the table while you deal with people and the venue. All of it free.
The bot is constantly improved based on real tournaments. If you need a feature that isn't there yet, message the developers right inside the bot with the /support command. Many features appeared exactly because organizers asked for them, and useful ideas get added quickly.
More about arbiting: a fallen flag in chess, a double forfeit, phones in the tournament hall, arbiting a chess tournament, late arrival and forfeit and fair play over the board.
At the board since childhood: hazy about his rating, precise about every rook he has blundered. Counts an evening as a good one if the opponent stayed to talk afterwards instead of rushing off to check with an engine. Message →
