I was wondering about that also. My son is in graduate school and has a paid graduate research assistant position over the summer, so I assumed we could not use the 529 money for his off-campus apartment. However, I just found out that he is required to register for a class in order to do the research position. I believe it's basically a "wrapper" for the research position, but we are trying to find out exactly which class to register for. He gets a tuition waiver for the majority of the tuition. For grad students, 3 hours is considered full time over the summer. So I believe since he is considered enrolled full-time for the summer, his off campus room and board are eligible to be reimbursed by out 529 plan, up to the cost-of-living amount as determined by the university. Which is a good thing because we were going to have some left-over in the 529 plan, but now it will be used up.