The Buffalo Bills and their quarterback Josh Allen have reached agreement on a six-year, $258-million contract extension, according to ESPN's Adam Schefter.

ESPN said the deal includes $150 million of guaranteed money, which is already bigger than that ($141.5 million) of Patrick Mahomes' 10-year, $503-million contract with the Kansas City Chiefs.

"I think the way that we structured the deal was obviously a chance for both sides to get a fair deal and feel like they won. To be here for eight more years and allow us to kind of move some things around to keep some pieces here – I'm not egotistical in how the money is put out or where it needs to be or how much it is. I want to win. Whatever it takes for us to win is what I'm willing to do," said Allen. 

"At the end of the day it's still a lot of money. As someone alluded to earlier, it's generational wealth and something to be super proud of. The ultimate goal for now is winning, and it's not going to matter if we don't win."

"Josh and I had an off-the-cuff conversation about doing a deal, with him wanting to make sure he could do a deal that took care of him and his family, but that we could still win around here. So I took all that into consideration as we structured this thing," said Bills general manager Brandon Beane.

Having started all 16 games for the Bills in his third season in the NFL, Allen averaged threw 4,544 yards which led to 37 touchdowns. The Bills were 13-3 in the season and won their first division (American Football Conference East) title since 1995. They beat the Indianapolis Colts and the Baltimore Ravens in the post season before losing to the Chiefs in the AFC Championship Game.

Allen was named for Pro Bowl for the first time and was runner up in the MVP competition.

"We've got a lot of work to do. I know that. And I'm just excited to put this behind me and start focusing on football now," said Allen.