The trio currently earns $325,000 per episode and may seek up to $1 million an episode.
Original stars Simon Helberg (Howard) and Kunal Nayyar (Raj) also are said to be looking for increases and will renegotiate together.
The new deals for Bialik and Rauch, who joined the series midway through its run and were promoted from recurring to regulars, will see their salary jump from$20,000-$30,000 per episode to the $60,000 ballpark, with increases each year taking them to $100,000 per episode by the end of their new contracts.
CBS has renewed The Big Bang Theory through its upcoming seventh season, which begins next week. The series is up for the best comedy Emmy this year, with Parsons again in the running for best actor. The show has yet to win in the comedy series category.