Franklin joined New England Patriots nose tackle Vince Wilfork as the first two players to be given the franchise tag in 2010. Under the franchise tag, Franklin has a one-year guaranteed contract offer at $7.003 million. Any team wishing to sign him other than the 49ers would have to be willing to give up two first-round draft choices. If Franklin would sign with another team, the 49ers would have seven days to match the offer.
General manager Scot McCloughan says the team still hopes to sign Franklin to a long-term contract before the start of next season.
"Aubrayo has proven to be a valuable contributor to our defense and we are looking forward to having him on our team going forward," McCloughan said. "Although a contract extension has not been completed at this time, we will continue to have discussions with Aubrayo and his agent."
Franklin would have been one of the more coveted free agents on the market if the Niners had not placed the tag on him as widely expected. He emerged as one of the top nose tackles in the league last season with 36 tackles, two sacks and an interception.
Franklin, 29, has recorded 291 tackles, four sacks, one interception and three forced fumbles in his seven-year career. He originally was a fifth-round pick by Baltimore in 2003 and joined the Niners as a free agent before the 2007 season.
With an uncapped year likely coming in 2010, teams have the option of using a franchise tag and an additional transition tag. It is unlikely the 49ers will use the extra tag on any other player.
John Clayton is a senior NFL writer for ESPN.com. Information from The Associated Press was used in this report.