Your ETD is protected by copyright the moment it is fixed in a tangible form, whether that is a PDF, DOCX, or LaTeX file. You therefore do not need to register your ETD with the Copyright Office to have a valid copyright in your thesis or dissertation.
However, sometimes it is helpful to register your copyright formally. For example, in order to file a copyright infringement lawsuit, you will need to have a received a completed copyright registration. Registering your ETD as a single literary work costs $35.00, and if your ETD includes additional works your authored e.g. photographs, music score, video, you can also register them as separate works (see the Copyright Office Circular 4 for a complete schedule of fees). The registration and payment process can be completed online and it generally takes 1-7 months for the Copyright Office to process your online application.
The first step is to go to the Copyright Office Registration Web Portal which provides more information about different types of works that can be registered. You will then create an eCO account and begin the process of registering your ETD.
The copyright office has a short video, showing the complete registration and payment process.
If you have any questions about how to complete a Copyright Registration, please contact the Office of Scholarly Communication and Publishing.