Digital rights to the books you would like to offer
An Apple ID for use on the iTunes Store with a valid credit card on file. One Apple ID can be added to multiple iTunes Connect providers.
A valid email account
A U.S. Tax ID can only be used once to sign up for iBooks.
If you are based in the U.S. or a non-U.S. entity that would like to sell books on the iBooks Store, you will need a valid U.S. Tax ID.