While Horford, a five-time All-Star, will move into the free-agent marketplace on June 30, there's motivation for both Horford and the Celtics to work toward an agreement on a new long-term contract, league sources tell ESPN.
Horford could help Boston's salary-cap flexibility with a new deal that starts below that $30.1 million salary.
Horford, 33, is a key member of the Celtics core and a favorite of management, coaches and teammates. Horford averaged 13.6 points and 6.7 rebounds for the Celtics this past season, his third with Boston since leaving Atlanta for a four-year, $113 million free-agent deal with the Celtics.
Horford has been to the Eastern Conference playoffs 11 times in his 12-year pro career. He won two national championships at the University of Florida.