Note: I am not an attorney. The following are generalizations only based on my study of copyright law and are not meant to be construed as legal advice. If you have a question, consult a competent attorney specializing in copyrights and intellectual property law.
Self-publishing your work does not change copyright. As soon as you set down your work in concrete form, you had copyright protection.
Even though some authors do not register their commercially-published works, the self-publisher is highly advised to do so. Two copies of the work are required in the application package.
copyright 1996-2002, Martha Beth Lewis