(Bankrate) — Parents seeking an investment safe haven that provides guaranteed returns may not find one in prepaid tuition plans. Long touted as a no-risk way to save for college, prepaid plans generally allow parents to purchase college credits at slightly above current market prices, and then cash them in when their child heads off to school. Some investors predict that prepaid plans may be a thing of the past in coming years. Since 2008, several prepaid plans have either closed down entirely or stopped new enrollment, as Tennessee recently did. The 10 remaining state-run prepaid plans and one independently operated plan provide good value, but also come with restrictions on where funds can be used and questions about whether funds are safe. Here’s what you need to know before investing in 529 prepaid tuition plans.