Technically, your song is copyrighted as soon as you finish writing it but you should register it with the Copyright Office since it will provide you with protection against anyone who tries to use your song without your permission (see How Do I Copyright My Songs?). The cost to register a song (using form PA) is only $30 and is a good investment. Although attorneys don’t usually recommend it, you can also do the “poor man’s copyright,” which entails putting written songs in a sealed envelope and mailing them back to yourself from your local post office.