Boss' agent, Scott Smith, tweeted Monday night that the Raiders told him Boss will be released Tuesday and become an unrestricted free agent. ESPN NFL Insider Adam Schefter reported the deal earlier.
Boss signed a $16 million, four-year contract last summer to replace Pro Bowl tight end Zach Miller. The deal included $6 million guaranteed, including $4 million in 2011 and $2 million in 2012, a league source told Schefter.
However, Boss wasn't utilized much in coach Hue Jackson's offense, finishing the season with 28 catches for 368 yards and three touchdowns in 14 games.
Oakland drafted two tight ends last year in David Ausberry and Richard Gordon, who played sparingly as rookies. The Raiders also have 2009 draft pick Brandon Myers under contract. Myers caught 16 passes for 154 yards last season and has 32 catches for 250 yards in three NFL seasons.
Boss is the latest player released in an offseason overhaul in Oakland, following defensive backs Stanford Routt, Chris Johnson and Hiram Eugene as new general manager Reggie McKenzie and coach Dennis Allen put their own stamp on the team in the first offseason since the death of longtime owner Al Davis.
The Raiders announced they tendered one-year contracts to restricted free agent defensive lineman Desmond Bryant and three exclusive rights free agents: fullback Marcel Reece, defensive end Mason Brodine and cornerback Bryan McCann.
The offers mean the Raiders have the right to match any contract offer to Bryant or receive compensation if he leaves. The three exclusive rights players can negotiate with other teams.
Oakland also confirmed it had restructured linebacker Aaron Curry's contract to keep him for this season. Curry was acquired last October from Seattle for a 2012 seventh-round pick and a conditional fifth-rounder in 2013.
The Raiders had previously restructured deals with quarterback Carson Palmer, defensive tackle Richard Seymour and safety Michael Huff to save more than $20 million against the 2012 salary cap. All teams must be under the $120.6 million cap by the start of the free agency period on Tuesday.
Linebacker Kamerion Wimbley, who got the franchise tag last offseason before signing a five-year, $48 million contract, also could be released. The Raiders owe him $6.5 million no matter what for 2012 and an additional $4.5 million if he is on the roster March 17. A source told ESPN.com senior NFL writer John Clayton the Raiders have not exchanged offers with Wimbley and the linebacker could be released if he doesn't agree to a restructured deal.
Wimbley was second on the Raiders with seven sacks last season and was also 15th in the league with 31 quarterback knockdowns and hurries, according to STATS.
Information from The Associated Press contributed to this report.