If you copyright your book before sending it to an editor, you are likely to end up with a slightly different version than you sent the U.S. Copyright Office. If the changes are just editorial or other minor revisions, you do not need to copyright the book again. The U.S. Copyright Office does not consider such changes to be substantial or a derivative work.
As an author, you may tweak the manuscript of your book once it has already been sent off to the U.S. Copyright Office. If this is the case, you may not need to register the revised copy. Only in certain instances is a copyright needed for a revised version of a book.
Minor Editorial Changes
Derivative Work Defined
The U.S. Copyright Office defines a derivative work as something that is derived from an already-existing work or works. It is also known simply as a new version of another work by the U.S. Copyright Office. Minor changes do not result in a derivative work. Only elaborate changes are considered to be a derivative work.
Major Revisions to Your Book
If you make major revisions to your book, it is considered to be a derivative work by the U.S. Copyright Office. In such instances, you can and do need to copyright the book. It is considered to be a separate work from the originally registered manuscript, which means you need an entirely new copyright for the revised version of the book. Changing the title or some phrases throughout the book is not enough for it to be considered a derivative work.
If you revise your book by translating it into another language, it is considered a derivative work and needs to be copyrighted. If you compile pieces from more than one book into a compilation and make only minor edits, it is not considered a derivative work and cannot be copyrighted. However, if you add some new material to that compilation it can be copyrighted. If you change the cover of the book, all of the chapter titles and have some editorial changes, it cannot be copyrighted. However, if you do those things as well as incorporate a new chapter or character, then it is considered a substantial change and you need to copyright the revision.