Brady's deal called for a signing bonus of $28 million, split into two $14 million payments.
He received the first installment when he signed the extension.
Brady is under contract through the 2019 season, although Patriots owner Robert Kraft said this week that the 39-year-old is preparing to play well into his mid-40s.
Kraft said he was confident Brady can emulate retired Hall-of-Famer Brett Favre, who played past his 40th birthday to lead the Minnesota Vikings into the playoffs in 2009-2010.
"At the level he performed, there is no one who would be happier than I am and our fan base," Kraft said of the prospect of many more years with Brady at the helm.