The NFL and the union have exchanged letters about health insurance coverage for the players after their contract expires March 3.
Union general counsel Richard Berthelsen asked if the owners intend to stop paying the players' health insurance premiums if there is no new CBA after March 30, 2011, and whether the players will be able to keep their coverage in place by paying the premiums themselves.
The NFL's Dennis Curran responded that an employer isn't obligated to provide wages or salary or to pay for certain continued benefits for employees during a work stoppage.
Curran added that under federal law, employees are entitled to continue their employer-provided health insurance coverage at their own or their union's expense.
The owners opted out of the collective bargaining agreement in 2008.
During an appearance Tuesday with Minnesota Vikings fans, NFL Players Association executive director DeMaurice Smith said he was working to figure out a plan to ensure medical coverage for players and their families should they be locked out by the owners.
Smith said he is dealing "with players where some of them have children who need heart transplants. We have several players who have children who are on kidney dialysis. We will have over 100 players who will have children who are born in the March, April, May timeframe. Right now, all of those players need health insurance."
NFL spokesman Greg Aiello said Tuesday it's one more reason to reach an agreement. He also pointed to the federal COBRA law that allows employees to continue their existing coverage without interruption at their own expense or the expense of their union.
"This means that no player or family member would experience any change in coverage for so much as a single day because of a work stoppage," Aiello told The Associated Press in an e-mail Tuesday. "The union surely knows this and there is no excuse for suggesting otherwise."
During the NHL lockout in 2004-05, the NHL players' union paid for substitute coverage.
That will be one of several options the NFL players' union will consider as it continues to prepare for a lockout.
For more NFL labor news, visit http://NFLLabor.com
The Associated Press contributed to this report.