American Opportunity Tax Credit at a Glance
A credit for tuition, required enrollment fees and course material for the first four years of post-secondary education for up to $2,500 per eligible student per year. Your modified adjusted gross income (MAGI) must be under $90,000 ($180,000 for joint filers) and you must not have claimed the AOTC or the former Hope Credit for more than four tax years for the same eligible student. Forty percent of this credit may be refundable.
Publication 17, Your Federal Income Tax - Chapter 35, Education Credits - Essential guidance
Publication 970, Tax Benefits for Education (revised January 7, 2015) - Detailed guidance