For every eligible dollar spent on educational expenses over $200, United Mileage Plus members will earn double miles until Sept. 30, 2007. No registration is required when you use your Mileage Plus credit card to pay for tuition, room and board, books, school donations and more at retail locations in schools. The maximum bonus miles you can earn during the promotion is 5,000 miles for Visa Signature, Gold Class Visa Signature and Platinum Class Visa Signature and 2,500 miles for Rewards and College Visa cardmembers. Be aware that not all school expenses will get double miles, for example, when a bookstore is operated as a separate business not owned by the school.