Although not necessary in order to copyright your book, registration with the US Copyright Office will make your registration a matter of public record, provide you with a copyright certificate and allow you to enforce your copyright protection in case of infringement. Copyright law protects your work for life plus 70 years. For more information about copyright registration, read the government copyright faq.
Register your copyright as soon as possible after the publication date for maximum protection and benefits. For example, if registration is made within three months of publication, predetermined payments are available to the copyright owner in an infringement lawsuit. If you register outside of the three month window, your financial remedy is limited to the actual damages you suffered from the infringement. Otherwise, a work registered within five years of publication brings with it the presumption that the work is copyrightable and that the facts stated in the registration certificate are true.
If you desire copyright registration and protection, CrossLink will complete your application and send the copyright office a copy of your book as part of their official record. Although it could take up to six months for you to receive your certificate, your copyright registration becomes effective on the date we register it with the copyright office.