IRS Publication 970 indicates that it can be used for graduate school as well (see the Appendix comparison), so it apparently doesn't need to be just for 4 years of undergraduate education.
It's a little confusing what "Not have finished the first four years of higher education at the beginning of the tax year" means. If I've completed 4 years of undergraduate education, but didn't use the AOTC at the time, then I can use the AOTC for graduate school years? Or can I only use it if undergraduate education took less than 4 years, e.g. I did it in 3 years? Or perhaps they mean it can only be used for 4 years of higher ed at a particular school to which you are applying the credit?
