Taylor Swift is working out the ''final details'' of her Super Bowl performance.

The 'Bad Blood' hitmaker is reportedly in line to be the star of the coveted half-time show at the annual sporting event, only 12 months after long-time rival Katy Perry wowed the NFL crowds.

A source told RadarOnline.com: ''It's hers [Taylor's] to refuse. Her team is working out the final details. She's just waiting on financials from the NFL before signing on the dotted line.

''Her main holdup is performing the year after Katy Perry did it, but she also feels it's the right way to close out the '1989' chapter of her career.''

Meanwhile, ahead of this year's Super Bowl game, which took place in February, an insider claimed Katy had planned to take a ''jab'' at the 'Shake It Off' hitmaker.

A source said at the time: ''Katy is in complete rehearsal mode for her Super Bowl performance, she wants to make it feel like a complete party and something that will be remembered forever.

''She wants to make a statement with her performance and show that she is the biggest female act in the world and she wants to show that to everyone including Taylor, who she has a feud with. In Katy's eyes, no one can compete on her level.

''Katy will be doing something on stage during her performance that will be directed towards Taylor. She is working on it to be a visual or a lyric related jab.''

During the performance, Katy's backing dancers were dressed in Taylor Swift-style outfits, prompting rumours this was the ''jab'' she had planned.