The Spanish daily said it had access to the document Messi signed with the Catalan club in 2017, which included fixed incomes and variables that could reach nearly 138 million euros ($167 million) each season. The newspaper said it is the most expensive contract ever paid to an athlete.
Messi would have to pay about half of that amount in taxes in Spain.
The report said the 33-year-old player has already secured more than 510 million euros ($619 million) of the total contract.
The leak comes as Barcelona tries to manage a huge debt prompted mostly because of the coronavirus pandemic. The club has been led by a caretaker board since president Josep Bartomeu resigned in October while facing a no-confidence motion. New presidential elections are scheduled for March 7.
The newspaper also detailed how Messi rewarded the club over the years, having helped it win more than 30 titles.
Messi has been with Barcelona for nearly two decades but asked to leave at the end of last season after saying he wasnt happy with the direction the club was headed. He had his request denied but will be able to leave for free when this season ends.
Barcelona can move to second place in the Spanish league with a home win against Athletic Bilbao on Sunday.