NFL Collective Bargaining Agreement

Article 13
Salary Cap Accounting Rules

Section 8(b)
Renegotiations and Extensions

(b)

No Player Contract, and no contract renegotiation or extension, may be agreed to between a Player and a Club for any term that expires prior to the last day of a League Year. All rights by a player to terminate a Player Contract must be exercised prior to the first day of any League Year to be terminated.