Strictly speaking, an IEP affords all of the protections and then some of a 504. The distinction at the end of high school is that the accommodations of the IEP should form the basis of the posr-secondary 504, but not all colleges will spontaneously or skillfully do so, if no one does it for them. So no, you don't need both during K-12 education, nor do you (or can you) after high school graduation. But for some students, it isn't a bad idea to transition from an IEP to a 504 near the end of high school, so that a college-forward-looking document exists prior to speaking with college disability services, and so that the document can be developed by educators who are familiar with the student's needs. It's. Also a good sheltered opportunity to practice self-advocacy and independence skills, before being let loose on the wide world.
