U.S. pop star Britney Spears has signed a $15 million deal to be a judge on \"The X Factor\" alongside Simon Cowell and L.A. Reid, E! News said. \"The contract is signed,\" a source close to the singer told the entertainment news network. \"There\'s been a lot of back and forth over the past few weeks as they negotiated the small details, but she\'s on. It\'s all completed and Britney is beyond excited,\" the insider said. \"She\'s ready for this. She can\'t wait to sit down next to Simon at the judges\' table and give this everything she\'s got. She is excited about showing the world that she can do this, and do this well. This is the perfect next stage in her career. Both Britney and Simon are very excited to work together.\" The show\'s producers have not yet announced who will serve as the host or fourth judge on Season 2 of the TV talent show.