How much does it cost to register a movie copyright with the US copyright office?

Basic copyright registration online is $35. By mail is $50. Legal firms can do it but may charge you several hundred. You don't need to file for a copyright in the US because US copyright law states that any original work put in a tangible medium is protected automatically by copyright. However, it is always a good idea to file in order to prove you are the copyright holder and that you made the work first.