NFL trades can become official when the new league year begins March 13.
The teams are prohibited from commenting on the deal or the terms.
The decision to trade Flacco shows the team's commitment to quarterback Lamar Jackson who was the team's first round pick past year.
Joe Flacco of the Baltimore Ravens throws a pass against the Denver Broncos on Sept. 23 2018 in Baltimore
Jackson went 6-1 as a starter, and led the Ravens to the AFC North Divisional crown with a 10-6 record.
The move opens the door for the Broncos to possibly trade or release Case Keenum, whose performance last season as starting quarterback was viewed generally as a disappointment. He is due $18 million in 2019, with just $7 million guaranteed. When the deal is completed, it likely will be for a midround pick, sources told ESPN.
Flacco, 34, is a former Super Bowl MVP, but he's largely underwhelmed since Baltimore's championship season in 2012. The Broncos will carry $10 million in dead money if they cut him.
One running gag on social media is the question about whether Baltimore quarterback Joe Flacco is elite. Flacco's quarterback rating hasn't risen above 90 since the 2014 season. According to Over The Cap's calculator, trading Flacco will free up $28.25 million in 2020 and $24.25 million in 2021.
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