Work for Hire: Is It Possible to Infringe on Your Own Work?

Short Answer:
Yes.

Long Answer:
If you are the sole owner of the copyright, then no. You cannot infringe on your own copyright.

If you have created a work but do not own sole copyright, then it is possible to infringe on your own work. You would of course need to obtain permission to create any reproductions or derivatives of someone else's work. But for your own original work, this most commonly happens when you have created a work under a "work for hire" agreement. This type of agreement can take many shapes. Often times it is with a publisher, a record label, or even part of your employer/employee agreement. A Work for Hire Agreement usually stipulates that the copyright ownership for works you create under the agreement goes to the entity who hired you. In other words, if a large movie studio hires you as work-for-hire to write the music to their next big movie, you'll need their permission before you can use that music in anything else. Other cases where you do not own the rights to your music can be when you are a cowriter with someone else, or you sell part or all of your copyright ownership to a record label or publisher. In situations like these, you could be sued for infringing on a song you wrote.