Nebula Award nominees and winners are chosen by members of the SFWA, though the authors of the nominees do not need to be members. Works are nominated each year by members in a period around December 15 through January 31, and the six works that receive the most nominations then form the final ballot, with additional nominees possible in the case of ties. Soon after, members are given a month to vote on the ballot, and the final results are presented at the Nebula Awards ceremony in May. Authors are not permitted to nominate their own works, and ties in the final vote are broken, if possible, by the number of nominations the works received.