The 49ers and Jimmy Garoppolo face two deadlines this offseason to reach an agreement on a long-term contract extension.

The first deadline is March 6. That is the last day on which teams can apply the franchise tag for the 2018 season. If Garoppolo remains unsigned on March 6, the 49ers will tag him as their franchise player, which – in essence – locks him in to a one-year deal worth $23.3 million, former NFL agent Joel Corry estimates.

The second deadline is July 16. That is the deadline for any club that designates a franchise player to reach a multi-year deal. After that date, the player may sign only a one-year deal until after the club’s final regular-season game.

The 49ers and Garoppolo’s agent, Don Yee, have kept conversations and negotiations private. And that is the way the 49ers plan to conduct business this offseason.

“One thing that we really believe is that those things should take place between us and his representatives and not occur and transpire in the public,” 49ers general manager John Lynch said. “That’s the way we’re going to treat that. You have our assurances, and the fans do, that we’d like nothing more than to make him a Niner for a long, long time.”

Two seasons of one-year franchise tags would provide Garoppolo with approximately $51 million. (Garoppolo made $3.5 million total in his first four NFL seasons.)

Garoppolo could also decide to play a season on a one-year deal in hopes of increasing his value far beyond what he would be likely to warrant now – after just seven NFL starts in four seasons. Because if he establishes himself as a top quarterback next season with the 49ers, any deal he signed this offseason would be considered a bargain for the team.

“That’s the nature of the beast with the quarterback market,” Corry said on the 49ers Insider Podcast. “If you sign a long-term deal, today’s deal is outdated tomorrow.

Detroit quarterback Matthew Stafford is the highest-paid player in the NFL with a deal that averages $27 million a season.

"He won’t be by the time the 2018 regular season rolls around," said Corry, whose work can be found at CBS Sports.

Corry points out that Stafford's agent, Tom Condon, also represents Atlanta quarterback Matt Ryan, who is scheduled to enter the final year of his contract.

"That’s Ryan’s floor," Corry said of Stafford's contract. "(Green Bay's) Aaron Rodgers is probably going to get a new deal. He’ll trump everybody. And if (Kirk) Cousins signs a long-term deal, he’ll be above Stafford, as well.”

Corry said he expects Garoppolo to sign a contract similar to the five-year, $125 million deal the Raiders worked out with quarterback Derek Carr last offseason.

"I think it’s going to be something close to that Derek Carr neighborhood," Corry said. "Maybe a shade under, but I think it’ll be in that general vicinity.”