Brady had two years left on his contract, paying him $9 million in 2016 and $10 million in 2017. Brady's salary-cap charge for 2016 was scheduled to be a team-high $15 million, and the extension likely will lower that number.
The Patriots have about $13 million in salary-cap space and are in the beginning stages of planning for possible extensions with a core group of defenders whose contracts expire after the 2016 season. That group includes linebackers Jamie Collins and Dont'a Hightower, defensive end Chandler Jones and cornerback Malcolm Butler.
The deal with Brady is not yet signed and may not be for a little while, sources said.
Brady turns 39 in August, and the new deal gives him the chance to play into his 40s, something he has expressed an interest in doing.