Decide which form to use. You generally register the composition itself as a "work of the performing arts" using Form PA. A recording would be registered as a "sound recording" using form SR. If you want to register both at the same time, use form SR.
Decide whether to register online. The Copyright Office recommends online registration because it is faster and cheaper. You can also submit electronic copies of your work instead of mailing hard copies if the work is unpublished or only published electronically. If you want to register online, go to the "Electronic Copyright Office" on the U.S Copyright Office website and follow the instructions to register and log in. Otherwise, print out the appropriate form.
Fill out the registration form. The electronic and paper versions require the same information about you and your instrumental work. If you are registering a composition and a recording together, make sure you list the composer and the musician separately, even if they are both the same person. If you have trouble with the forms, you may want to consult a copyright attorney or an online legal document service.
Pay the filing fee. If you are registering online, you can use a credit or debit card. Otherwise, write a check for the appropriate amount. You can find the current fees on the U.S. Copyright Office website.
Prepare copies of the instrumental work. If you are registering a composition you will need copies of the lead sheet or sheet music. If you are registering a recording, you will need copies of the recording. Either way, make two copies if the work has been published and one copy if it has not. There is an exception for published compositions that only exist as recordings, are published by "rental, lease, or lending," or are part of collective works. In all three cases, you only need to send one copy.
Complete your application. If you are registering online, either submit the copies of your work electronically or enter information about mailing them in. If you mail them, make sure to do it within 30 days. If you are registering by mail, send the Copyright Office your completed form, payment and copies of your work.