Kiffin was fired in September for cause after what owner Al Davis described as acts of insubordination and lying.
Kiffin filed a grievance and is seeking two months pay for the time he was unemployed before being hired at the University of Tennessee.
The Raiders sent a letter to Tennessee, explaining how they believe Kiffin breached his contract, violated NFL rules and was insubordinate despite warnings from Davis.
Kiffin had a 5-15 record with the Raiders.
Associated Press helped contribute to this report.