In a procedural formality, the NHL has provided the required 120-day notice to the players' union in order to make changes to the CBA, an NHLPA spokesman confirmed to ESPN.com.
The current CBA expires Sept. 15. If either party wanted to extend the agreement, the current one would automatically have been extended for another season.
At the general managers' meetings in mid-March, commissioner Gary Bettman said he was "not particularly concerned" about the negotiating timeline.
A week after that, Bettman said he was ready to meet with the union, but that the NHLPA had not indicated it was ready.
Revenue sharing is expected to play a large role in the talks, with NHL owners wanting to cut the players' share of league revenues from 57 percent.
But the league also wants to avoid a work stoppage like the one that shut down the 2004-2005 season.
The current contract was the league's first with a salary cap.
"Obviously, the system we have made some important fundamental and dramatic improvements," Bettman said in March. "We have, as I said, great competitive balance but I'm not getting into the specifics."
Donald Fehr, who previously led the Major League Baseball players' union, became executive director of the NHLPA in December 2010.
Fehr wants to include a negotiating committee of players in talks, meaning the earliest that CBA negotiations could begin is mid-to-late June after the Stanley Cup finals are over.
Information from ESPNBoston.com's James Murphy and The Associated Press was used in this report.