The contract is expected to be done soon, well before the training camp deadline Carr had given the Raiders, according to sources.
The sides still are finalizing language, but the deal could be announced as early as the end of this week. Once signed, Carr's new contract will make him the NFL's highest-paid player in terms of new money average, a source told ESPN's Dan Graziano. That new money in Carr's deal will average more per year than the amount given to Indianapolis Colts quarterback Andrew Luck, who currently tops the list at $24.6 million.
Cousins and the Washington Redskins are trying to get a long-term deal done by the July 17 franchise deadline.
Carr's deal could potentially be backloaded to save in taxes. The deal could be backloaded until the Raiders move to Las Vegas because there is no state tax there whereas California's tax rate is 13.3 percent. Carr could save hundreds of thousands of dollars, if not millions.
Carr, 26, passed for 3,937 yards and 28 touchdowns with just six interceptions last season, helping lead the Raiders to their first postseason appearance since 2002. He suffered a broken fibula in Week 16 and missed Oakland's playoff loss to the Houston Texans, but he has been a full participant in the team's offseason activities.
Carr, speaking last week at the Raiders' minicamp, said he was happy to be "just playing ball again."
"The hardest part was taking the first rep, because the last rep you remember was like, 'Oh snap, I broke this thing,'" Carr said. "But as soon as the ball was snapped, it was a blessing. It kind of all went away."
Information from ESPN's Paul Gutierrez was used in this report.