Each season NFL teams can elect to carry over unused cap money to the next season. That is, of course, if they have any to carry over. On average, NFL teams this year will carry over around $9 million in unused cap, topping out at the Browns carrying over some $50 million on down to the Chargers who will carry over just above $113K.
The Raiders are just below the average, carrying over at $8 million in carry over according to NFLPA official figures. That is the ninth most money carried over.
According to two different cap sites, overthecap.com and spotrac.com. the Raiders are between $44 million and $47 million under the cap. The $8 million in carryover would raise those figures to between $50 million and $55 million depending on projected salary cap.
As we get closer to the end of the league year and the start of free agency, exact amount of money available under the salary cap for each team will become more clear. Either way, the Raiders will have sufficient money to spend this offseason to lock up their own players (i.e. Derek Carr) and be a player in free agency.