The Sun says they would have to pay Mourinho a staggering £12million if they sacked him this season.
The United boss has made it clear he is unhappy following a disastrous pre-season tour of the US.
He has also not been backed as he had hoped in the transfer market, and only expects one more signing.
Mourinho has two-years left on his deal, and would usually be entitled to his full £12m-a-season if he was axed.
But it is understood he will only receive 12-months of his huge salary, after a clause was inserted in his contract.