Fifteen Redskins, including quarterback Joe Theismann, defensive tackle Dave Butz, cornerback Joe Lavender and linebacker Brad Dusek, will become free agents Monday after failing to sign new contracts with the team.

The Redskins, however, have sent 12 of the players qualifying contract offers so they will retain the right to negotiate with them, match the offer they may receive from another team, or receive compensation if they sign with another team.

Center Dan Peiffer and cornerback Ray Waddy were not sent qualifying offers. If they sign with another team after April 1, the Redskins are not eligible for compensation. Center Bob Kuziel, who also would have been a free agent, has retired because of a back ailment.

Thirteen Redskins who are entering the option years of their contracts have been informed by Washington that their options will be renewed next season, including fullback John Riggins.

Riggins and the Redskins still are waiting for a decision by a league arbitrator on his claim that Washington illegally prevented him from playing during the 1980 season. If Riggins wins the grievance, he could be awarded his 1980 salary. If that happens, he will have played out his contract, making him a free agent.

To cover that possibility, General Manager Bobby Beathard said Riggins also was sent a qualifying offer. Riggins made $300,000 last year and is eligible for at least a 10 percent raise, increasing his salary to a minimum $330,000.

Theismann and the 11 other Redskin free agents who have been tendered contract offers now can negotiate with other teams. They have until April 15 to present an offer sheet to the Redskins, who can either match it or receive compensation. In Theismann's case, that compensation would be two first-round draft choices.

"We don't have any more talks with Joe scheduled," Beathard said. "We are waiting for him to set something up. But we have every intention of signing him."

The Redskin free agents include: Theismann, Butz, Dusek, Lavender, punter Mike Connell, defensive end Karl Lorch, receiver Terry Metcalf, tight end Bob Raba, fullback Rickey Claitt, tight end Richard Caster, linebacker Pete Cronan and linebacker Charley Weaver.

Those Redskins entering their option year are Riggins, linebackers Rich Milot and Quentin Lowery, receivers Virgil Seay, Alvin Garrett and Ricky Thompson, fullback Wilbur Jackson, tight end Don Warren, halfbacks Otis Wonsley and Nick Giaquinto, defensive linemen Pat Ogrin and Dallas Hickman and cornerback LeCharls McDaniel.

Players in their option year can negotiate a new contract with their present team. If that fails, they receive an automatic 10 percent raise.