Manuscript Preparation, Copyediting, and Proofreading
Q. When the publication date appearing at the top of the copyright page (identical with the copyright) differs from the date appearing in the Cataloging-in-Publication (CIP) data at the bottom of the page, which is preferable to use for purposes of documentation? I have found that the CIP date is often, or at least occasionally, one year earlier than the publication date appearing as copyright (e.g., 2011 and 2012).
A. Use the information provided by the publisher, not the CIP. As you say, the actual publication of a book may be delayed significantly after CIP was applied for, and publishers don’t always file a correction. In fact, many publications don’t list CIP data or aren’t eligible for the program, which is metadata for librarians.