S529 plans offer a tax-advantaged way to fund college. With a prepaid tuition plan, tuition is guaranteed regardless of its cost when the child attends the school. Downsides are that there’s uncertainty in how benefits will be applied if the child attends a different school and costs other than tuition aren’t covered. With a savings plan, withdrawals used to pay qualified expenses (such as tuition, books and room and board) are generally income-tax-free. A downside is that you don’t have direct control over the plan’s investments.