Not knowing you precise situation, I recommend you review the IRS Publication 970 (https://www.irs.gov/pub/irs-pdf/p970.pdf) which details the credits and deductions available to taxpayers along with the restrictions on who can claim them.  Being in graduate school you would not qualify for the American Opportunity Credit, but you may be qualified for the Lifetime Learning credit depending upon your age, whether you are a dependent, what expenses you had for graduate school and what scholarships and grants you had.