According to the Sun, the Hollywood couple is planning to say their vows next month, in October. The ceremony and party will take place on the island of Ibiza, where they were spotted vacationing in July.
The "Assassins Creed" actor, 40, is set to throw a huge, expensive bash at a five-star resort for his bride, 28.
"He's splashing out big time and it's going to be the party of the year," a source told the mag.
But, the duo is keeping the details of the soiree as under wraps as possible.
Guests apparently don't even know the location of the wedding. All they've been told is exactly what day to arrive on the island, and they'll be whisked off to the hotel.
And, get this .... Michael is allegedly dipping into his own pockets to put everyone up at the fancy resort for the wedding festivities.
He and Alicia met on set of the 2014 flick "The Light Between Oceans."