The Argentine is yet to pen an extension at the Nou Camp but Barca are ready to pay big to keep him.
The Argentine is out of contract at the end of the season and is yet to put pen to paper on an extension.
Last month, Barcelona president Josep Maria Bartomeu insisted the only thing missing was his signature after agreeing a new £500,000-a-week deal.
And Catalan paper L’Ara report Barca will hand Messi a bonus between £79m and £85m when he agrees his contract.
With Messi having fired Argentina to World Cup glory this week, he has opened the window to sign his contract during the next break in November.
Barca could pay for the deal with help from a new Nike deal and a stadium sponsor for the Nou Camp.
They are preparing for a £500million renovation of the iconic venue, where the capacity will be increased to an incredible 105,000 by the end of the 2021/22 season.
But alongside a new roof, high definition video scoreboards and plush VIP facilities, the stadium is also poised to take on a new name.
Sport report that Barca have already began negotiations with global companies over the possibility of taking the rights.
The Catalan giants are hoping for in excess of €200million (£179m) in a deal.