Jackson is suspended for the rest of the season and is not eligible for possible reinstatement until Sept. 22, 2011. He will not be paid while he is suspended.
"Tanard is a talented young man whom we hope is able to use this year to put his troubles behind him and ultimately return a stronger man and player," general manager Mark Dominik said. "It's up to Tanard whether the teams and our fans eventually realize his considerable promise."
Jackson was supended for the first four games of the 2009 season for violating the substance abuse policy. Despite the four-game ban last season, Jackson finished with five interceptions in 12 starts. He had 13 tackles in two games this season, helping Tampa Bay to its first 2-0 start in five years.
Fourth-year pro Sabby Piscitelli, who lost the strong safety job to Sean Jones during training camp, is one possible replacement. Rookie Cody Grimm, a seventh-round pick, is listed as the backup on Tampa Bay's depth chart. Corey Lynch, a third-year player, is listed as the third team free safety.
"Talking to coach [Raheem] Morris, obviously we have a position open. He's going to take the next few days to determine who's going to be the starter going forward," Dominik said. "We are happy we did have guys like Corey Lynch and Cody Grimm and Sabby Piscitelli, and obviously Sean Jones, who played well enough to be on this team."
When Jackson, who has eight career interceptions, returned from last year's suspension, he talked about how difficult it was being away from the team and how much football means to him.
"I could sit here and go on forever as to how much I learned. The main thing is that this is what I love to do, this is what I'm blessed to do," he said in October.
"I definitely felt I let my team down," Jackson added at the time. "I disappointed myself, but your actions affect others around you, and that's one thing that hit home."
Jackson, 25, was a fourth-round pick by Tampa Bay in 2007.
NFL blogger Pat Yasinskas covers the NFC South for ESPN.com. The Associated Press contributed to this report.