Per Shams Charania of The Athletic and Stadium, Richardson will opt in to the deal to facilitate a trade to the Boston Celtics. Charania reported the Mavericks will be receiving Moses Brown in the deal.
The C's are working to retool their roster under new president of basketball operations Brad Stevens. They began the offseason by trading Kemba Walker and two draft picks, including the 16th choice in 2021, to the Oklahoma City Thunder for Al Horford, Moses Brown and a 2023 second-round draft pick.
Kris Dunn, Bruno Fernando and a 2023 second-round pick will be sent to Boston in the trade.
Meanwhile, the Mavericks could be making moves now with a bigger goal in mind for the start of free agency.
The Athletic's John Hollinger noted the Mavs could come out of this with just enough cap space available to potentially make Kyle Lowry a max contract offer.
Richardson was acquired by the Mavs in a November trade with the Philadelphia 76ers.
The 27-year-old averaged 12.1 points, 3.3 rebounds, 2.6 assists and 1.0 steal across 59 appearances during the 2020-21 season. But he struggled with his offensive efficiency, shooting 42.7 percent from the field, including 33.0 percent on threes.
The 6'5" Richardson rated as an above-average defender, which helped him overcome the struggles with his shot to rank a modest 56th among 116 qualified shooting guards in ESPN's real plus-minus.
In December, the University of Tennessee product explained his ability to fill a wide range of roles was his best asset.
"The thing I can bring is toughness. I can bring leadership and I can bring defense," he said. "I'm kind of a gap-filler. From night to night, I can fill in where I need to."
Richardson has averaged 12.3 points across 373 appearances during a six-year career that has included stops with the Mavericks, Sixers and Miami Heat, who selected him in the second round of the 2015 draft.