The server may not deliver before the receiver is ready, but the receiver cannot try to return the serve and then claim unreadiness. The BWF Laws pair protection against a quick serve with a rule against undue delay by either side.
BWF Law 9.4 says the server shall not serve before the receiver is ready. Law 14.2.1 supplies the consequence: it is a let when the server serves before the receiver is ready.
A let does not award either side a point. Under Law 14.3, play since the last service does not count and the player who served last serves again. The existing score and service entitlement remain in place.
Law 9.4 expressly states that the receiver is considered ready if a return of the service is attempted. A receiver who swings at, reaches for, or otherwise attempts to return the delivered shuttle cannot rely on the receiver-not-ready let after seeing the outcome.
This prevents a conditional claim: a player cannot treat a successful return as live but call for a let when the attempted return misses. The observable attempt establishes readiness for that service.
Law 9.1.1 says neither side shall cause undue delay to the delivery once server and receiver are ready. It also specifies that delaying the start of service after the server completes the backward movement of the racket head is undue delay.
The protections are reciprocal. The server cannot rush an unready receiver, and the receiver cannot repeatedly withhold readiness as a tactic. In an officiated match, the umpire manages delay and misconduct under the applicable Laws and technical-official instructions.
Once the players are ready, Law 9.2 defines the start of service as the first forward movement of the server's racket head. Law 9.3 says the service is delivered when the racket hits the shuttle or the server misses it while attempting to serve.
These definitions help order the facts, but readiness must exist before the serve is delivered. A server should not use a sudden action to manufacture uncertainty about whether the receiver had time to become ready.
When a receiver attempts a return and is therefore considered ready, the service is still judged against all of Law 9. Feet, service-court position, release, initial base contact, the 1.15-metre limit, continuous forward motion, and shuttle flight can still produce a service fault.
Law 14.2.2 separately provides a let if, during service, the receiver and server are both faulted. That is a different basis from an early serve and should not be used when the facts show only one side committed a fault.
In doubles, the correct receiver is the player diagonally opposite the correct server under Law 11. The partners may stand anywhere within their respective courts during delivery provided they do not unsight the opposing server or receiver.
A readiness dispute concerns the correct receiver. If the receiver's partner hits the served shuttle, Law 13.2.3 makes that a fault; partner contact is not a substitute return that repairs an incorrect receiving sequence.
Law 14.1 allows a let to be called by the umpire or, if there is no umpire, by a player. In self-officiated play, the best practice is to stop immediately, state that the receiver was not ready, and replay with the same server rather than finishing the rally and making a result-dependent claim.
The law does not prescribe one universal readiness gesture. Competition instructions may add procedures, but players should use clear communication and avoid creating delay.
This explainer applies Badminton World Federation Laws of Badminton in force 26 April 2025, Version 5.0 (2), especially Laws 9.1, 9.2–9.4, 13.2.3, and 14. Competition-specific technical-official procedures may supplement how readiness and delay are managed.