Per ESPN's Adam Schefter and Field Yates, the Redskins are withholding the remaining $5.1 million of Williams' $10.85 million base salary for 2019 after placing him on the non-football injury list.
Washington ended Williams' season by making the roster move Thursday.
NFL Network's Ian Rapoport noted the Redskins weren't obligated to give Williams his remaining salary.
Schefter and Yates cited other players who were placed on the non-football injury list this season, including Jason Pierre-Paul (Tampa Bay Buccaneers) and Russell Okung (Los Angeles Chargers). Their teams chose to pay them 35 to 40 percent of their salaries while they were unable to play.
Williams could go through the NFL Players Association to contest Washington's decision not to pay him, per Mark Maske of the Washington Post.
In an interview with USA Today's Mike Jones, Williams said "the bridge has definitely been burned" in his relationship with the Redskins.
Williams, who held out until Oct. 29, and Washington have been locked in a dispute stemming from how the team handled a growth on his head that turned out to be cancerous.
Williams told reporters Oct. 31 "I almost lost my life" after being diagnosed with cancer. He said doctors removed a tumor from his skull this offseason that was discovered six years ago by Washington's medical staff, who downplayed it at the time.
The Redskins still have Williams under contract through next season, but his dead cap number of $2 million in 2020 would allow the team to move on without significantly impacting its salary situation.