Perpetual check

Check is a direct attack on the king that requires a reply. In a perpetual check, one player can force a sequence of checks that returns to the same pattern and that the opponent cannot stop without entering the cycle again. Queens and rooks often create it because they can check from a distance in several directions.

The official laws do not contain a separate rule that simply awards a result for “perpetual check.” In games played in person on a physical board, the cycle normally enables a threefold repetition claim when the same position appears for the third time. Five appearances make the draw automatic. In official online competitions of the International Chess Federation (FIDE), the platform automatically declares the draw on the third occurrence.

Three checks alone are not enough. Complete positions must repeat with the same player to move, the same pieces on the same squares, and the same legal possibilities. Before treating the sequence as forced, check whether the defender can reach safety, block a rook, bishop, or queen check by placing a piece in between, capture the checking piece, or otherwise change the position.

Perpetual check is especially useful as a defensive resource. A player with fewer pieces or facing a checkmate threat, meaning the possibility that the opponent will attack the king with no legal reply on the next move, may turn a likely loss into a draw, a result with no winner. If the cycle can be broken without returning to the checks, the perpetual is not forced.