Question: What Is Mandatory Deposit?
Answer: The United States has mandatory deposit requirement for all works published in the United States. (See the definition of
publication).
The owner of copyright has a legal obligation to deposit into the US Copyright Office copies of their work within three months of publication in the United States.
In general, two copies or in the case of sound recordings, two phonorecords of your work must be given to the Library of Congress.
Failure to make the mandatory deposit can result in fines and other penalties but it does not affect copyright protection.
Exceptions
Certain categories of works are exempt entirely from the mandatory deposit requirements, and the obligation is reduced for certain other categories. See -
Mandatory Deposit of Copies or Phonorecords
You Can Do A Mandatory Deposit And A Copyright Registration Together
For works published in the United States, the copyright law contains a provision under which a single deposit can be made to satisfy both the deposit requirements for the Library and the registration requirements.