there's only a tax problem if you don't pay your taxes. if defending your copyright is an issue, you may need to register for copyright. but copyright for an author is normally understood to exist at the time the work is created, and does not require registration. if it did, then most artists could not make a living and the only source of art would be corporations.Yes, you can publish your thought in form of book without government license.
But there is no evidence about the real author.
If other person steal your contents, you will confront difficulty in proving
And if you sell your book. that will provoke tax problem.