The 31-year-old 'Toxic' hitmaker is due to leave the show after this week's two-night grand finale, along with music mogul judge LA Reid, reported Daily Star.
"Simon had hoped Britney would be a ratings boost but that simply hasn't happened. It's no coincidence she is not in talks about a new deal," said a senior executive at Fox
Fellow judge Demi Lovato is already in contract negotiations with Simon Cowell's production company for next year's show.
Only eight million viewers watched this season's episodes compared to an average of more than 12 million last year.
"She just doesn't seem to be cut out for a TV talent show," the senior executive added.