Official Rules of Racquetball

3.2 - Start

The server may not start the service motion until the referee has called the score or "second serve." The referee shall call the score as both server and receiver prepare to return to their respective positions, shortly after the previous rally has ended--even if the players are not ready. The serve is started from any place within the service zone. (Certain drive serves are an exception. See Rule 3.6.) Neither the ball nor any part of either foot may extend beyond either line of the service zone when initiating the service motion. Stepping on, but not beyond, the lines is permitted. However, when completing the service motion, the server may step beyond the service (front) line provided that some part of both feet remain on or inside the line until the served ball passes the short line. The server may not step beyond the short line until the ball passes the short line. See Rule 3.9(a) and 3.10(i) for penalties for violations.