Many professional songwriters don’t copyright songs until they begin earning income. The reason is both cost and time involved. Non-professionals often copyright their songs due to fear of infringement (their songs being stolen). Again, this can be expensive, but if it makes you feel comfortable, you can always exercise that option by visiting www.copyright.gov.
To help the creative minds, including songwriters from all genres of music, professional and amateur, who are committed to protecting the rights and future of the profession of songwriting.