The contestant on the American show "Dancing with the Stars" and former model said she needed that amount "just to get by," the Sun reported.
The proposal, which McCartney was expected to reject, would be more than $6.7 million annually, Sky News said.
The couple announced their split last May after four years of marriage. They have one child, Beatrice, 3.
Swim Week Miami Beach 2014 [PHOTOS]