Real president Florentino Perez has vowed to bring back Mourinho to the Bernabeu, 13 years after he left the club in 2013, as he seeks re-election this weekend.
Benfica released a statement saying that Perez had told them of his "firm intention to recruit" Mourinho, while stipulating that the Portuguese boss's release clause was worth 15 million euros.
Previous media reports had suggested that it could cost the Spanish giants as little as three million euros.
Mourinho has already appeared in a video on Perez's Instagram account, affirming that he was ready to return to the club he first joined in 2010.
During his tenure, he won one LaLiga title, a Copa del Rey and a Spanish Super Cup.
Appointing the divisive Mourinho would be a gamble on the part of Perez after Los Blancos finished without a major trophy for a second consecutive season.
But Perez sees Mourinho as the man to bring some discipline to a divided dressing room in which player power is rumoured to have got out of control.
Mourinho joined Benfica in September 2025 and led them to an unbeaten league season, although they only finished third.
He has one year left on his contract.