07/25/2012 at 09:00 AM EDT
On TV, they play one big (mostly) happy family.
But the cast of Modern Family
is facing some serious off-screen drama after six of the show's lead actors filed a lawsuit Tuesday in Los Angeles Superior Court to void their contracts, according to legal documents obtained by PEOPLE.
, Ty Burrell, Julie Bowen, Eric Stonestreet, Jesse Tyler Ferguson and Ed O'Neill, who was originally negotiating separately, say their 20th Century Fox Television contracts break California's "7-Year Rule," which prohibits personal services contracts that span longer than seven years. (Their current contracts oblige them to the Emmy-winning ABC series from 2009 to 2016.)
has been a breakout critical and financial success," the lawsuit states. "That success, however, has been built upon a collection of illegal contracts."
A 20th Century Fox spokesperson told the Associated Press that the studio had no immediate comment on the legal action.
Production on the show's fourth season was due to begin with a table reading Tuesday, although salary negotiations have set back production.
The suit also says that the cast's contracts limit the pay raises they can receive each season, reports the AP. Vergara, who portrays the sultry Gloria, can't receive more than a 5 percent pay increase per season. However, her costars are capped at 4 percent.
Vergara, 40, Burrell, 44, Bowen, 42, Stonestreet, 40, and Ferguson, 36, are being offered $150,000 per episode, in addition to a $50,000-per-episode bonus for season 4, sources tell the Hollywood Reporter
. O'Neill, 66, who starred in the Fox hit Married … with Children
until 1997, reportedly takes home larger paychecks than his costars.