EXCLUSIVE: CBS‘ The Big Bang Theory is on track to go on for at least two more seasons. I hear that original cast members Jim Parsons, Johnny Galecki, Kaley Cuoco, Simon Helberg and Kunal Nayyar are finalizing new two-year contracts to continue on the Warner Bros TV-produced comedy series, paving the way for a two-year renewal, which I hear also is nearing the finishing line. If negotiations between CBS and WBTV conclude successfully, it would bring the blockbuster comedy to 12 seasons. The network and studio declined comment.

This is a pretty quick turnaround compared with the cast negotiations three years ago, when talks dragged on during the summer, leading to a weeklong delay in start of production for Season 8. Back then, CBS and WBTV closed a three-year renewal for the show in March, which was followed by the protracted talent negotiations. This time, talent conversations have been going on parallel tracks with license fee renewal talks between CBS and WBTV and negotiations for The Big Bang Theory prequel series, Sheldon, which is in the works for next season. CBS is covering most of the series’ production cost, a standard practice for a show late in its run.

I hear the five original stars — Parsons, Galecki, Cuoco, Helberg and Nayyar — are getting the same salary under “most favored nations” terms, ensuring financial parity among the quintet. The paychecks are believed to be close to what the five are making this season, around $1 million an episode, with the difference possibly used to boost the paychecks for co-stars Melissa Rauch and Mayim Bialik.

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The Big Bang Theory, which launched with Parsons, Galecki and Cuoco as the three main leads, gradually evolved into a true ensemble show. Three years ago, Parsons, Galecki and Cuoco negotiated together for equal salary, as did Helberg and Nayyar, who were then in a different tier. I hear that by the current eighth season, all five reached parity at about $1 million an episode. In the previous go-round, Parsons, Galecki and Cuoco also negotiated an increase in their ownership stake, and Galecki and Parsons received producing deals at WBTV. (I hear Cuoco got monetary compensation instead.) As a producer, Galecki landed a pilot order at CBS for comedy Living Biblically, while Parsons is producing the Sheldon offshoot.

“These are going to be, I think, the normal tough negotiations when you in a situation like this, but we are guardedly optimistic,” CBS Entertainment president Glenn Geller told Deadline of the BBT talks last month.

With original cast members Parsons, Galecki, Cuoco, Helberg and Nayyar almost done, negotiations are expected to gain momentum with Big Bang co-stars Melissa Rauch and Mayim Bialik, whose contracts also are up.

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Rauch and Bialik, both introduced as guest stars in Season 3 and becoming regulars in Season 4, had been on a different track than their cast mates, earning $175,000 an episode in their most recent deal, according to sources. Because their characters have become an integral and equal part of the show’s ensemble, with Bialik earning four Emmy nominations for her role, and because of where they are salary-wise due to their later start on the show, both are primed for a major salary bump for the next two seasons. Sources indicate the two may be seeking parity with their co-stars.

While Big Bang‘s production price tag is creeping up to an eye-popping $10 million an episode, the comedy series is in its own league performance-wise. In its 10th season, The Big Bang Theory is the most-watched scripted series on television, currently edging NBC’s Sunday Night Football for the top spot with an average of 20.13 million viewers in Live+7, vs 19.75 million for the NFL games. In adults 18-49, it is the No. 2 program behind SNF with a 5.4 Live+7 rating and the highest-rated scripted broadcast show by a wide margin. What’s more, Big Bang is still packing the elusive live audience, averaging more than 14 million live viewers for an original telecast.

Additionally, BBT has been used to launch numerous new CBS series, most recently Kevin Can Wait, The Great Indoors, Life in Pieces, Mom, The Odd Couple and Scorpion.

The series has generated more than $1 billion for Warner Bros TV in syndication revenue. The dearth of big network sitcoms in the past few years might help the show continue to generate strong revenue for its additional seasons on TBS and in broadcast syndication despite the fact that both the cable network and the stations have a cap on how many seasons of Big Bang they have to pick up at the original very high price, which has been met, making suture seasons potentially less valuable.

“If there was another Big Bang Theory, I can promise you we’d buy it,” TNT and TBS president Kevin Railly told Deadline in January when discussing the off-network market.