The 26-year-old can become an unrestricted free agent next offseason; in late August, Seguin expressed disappointment that a new deal had not yet been reached.
"We are deep in discussions. It's moving in the right direction," Stars general manager Jim Nill told team reporter Mark Stepneski.
Talks picked up steam upon Seguin returning to Dallas prior to training camp.
"I think once he got down around the team and stuff, that was important for him," Nill added. "Like I said, things are moving in the right direction.
"I'd like to get it done before the season starts, but with negotiations, you never know. But I think both parties would like to get it done before. I think it's always been the plan to get it done before the season starts."
Time is of the essence, as Dallas opens the season Oct. 4 against the Arizona Coyotes.