He owes the Bengals 4 more seasons. If he sits out 2011, he will still owe them 4 more seasons. If he sits out for 4 years.....he will still owe the Bengals 4 more seasons when he comes back.
But if he shows up, the Bengals have to pay him or cut him. $11.5 million this year, $11.5 million next year, $13M in Year 3 (2013), and $14M in Year 4 (2014). There's also a $9 million "Option Bonus" which, as far as I can tell, must be paid if he's on the roster at any time in 2011.
The ideal move for Palmer would have been to report the day before the season started. Now his best move is to pull a Vincent Jackson and show up just before Week 10, so he can collect 38% of his salary and burn a year off the contract. And he may still get that $9 Million option bonus.
Every week Palmer sits at home, Mike Brown gets $72,000 in free money.