The teams front-loaded contracts in 2010 to save money under the cap over the past two seasons, according to several reports Monday.
Citing sources, ESPN.com reported the Cowboys will lose $10 million and the Redskins $36 million from the projected $120.6 million salary cap. NFL.com said teams were warned not to push spending into the uncapped year as a way of getting around future salary caps.
The Cowboys have said they followed the rules, while the Redskins say they were not made aware of any adjustments to their salary cap.
The NFL released a statement Monday:
"The Management Council Executive Committee determined that the contract practices of a small number of clubs during the 2010 league year created an unacceptable risk to future competitive balance, particularly in light of the relatively modest salary cap growth projected for the new agreement's early years.
"To remedy these effects and preserve competitive balance throughout the league, the parties to the CBA agreed to adjustments to team salary for the 2012 and 2013 seasons. These agreed-upon adjustments were structured in a manner that will not affect the salary cap or player spending on a league-wide basis."
ESPN.com reported the Cowboys and Redskins can split their cap losses over the next two seasons in whatever way they prefer with the money going to the other teams in the league.
In a statement, the Cowboys said they were in compliance with all NFL salary cap rules during the uncapped year.
"We look forward to the start of the free agency period where our commitment to improving our team remains unchanged," the Cowboys said.
Meanwhile, the Redskins said they have received no written documentation from the NFL about adjustments to their salary cap for next season.
"Every contract entered into by the club during the applicable periods complied with the 2010 and 2011 collective bargaining agreements and, in fact, were approved by the NFL commissioner's office," Redskins general manager Bruce Allen said in a statement. "We look forward to free agency, the draft and the coming football season."