You must be half time or more for the more generous American Opportunity Credit (AOTC). But a single course qualifies for the non refundable Lifetime Learning Credit (LLC) or Tuition and Fees Deduction (TFD). TurboTax will select the best one for you. It's usually the LLC which is 20% of qualifying expenses, e.g. 20% x $2500 = $500.
