Benson's attorney Sam Bassett says the 28-year-old Benson earned time off his sentence by doing work mopping floors and helping paint crews. State law also allows inmates to begin earning time off as soon as they enter jail.
Benson pleaded no contest to two misdemeanor assault charges on Monday in Austin. He was arrested in 2010 for punching a bar employee. He was arrested again in July for punching a former roommate.
Benson has been the Bengals' leading rusher each of the last three seasons, going over 1,000 yards in 2009 and 2010.