As an addendum to the other responses, understand this:
Colleges work in academic years, while the IRS works in calendar years. So whatever occurred in 2018 just flat out does not apply to your 2019 tax return in any way, form or fashion.
With the above information you now understand that it takes 5 calendar tax years to obtain that 4 year degree. So that's why you want to pay for that senior year last semester "before" that 5th calendar year starts. Remember, education expenses are claimed in the tax year they are paid and it flat out does not matter what tax year is paid *for*.
So if you claimed the AOTC for her first four years in college (2015-2018) you do not qualify for the AOTC for 2019. (But you may qualify for the lifetime learning credit which is a max of $2000)
But from what I see, since she did not attend as a full time student for at least 5 months (the months do not have to be consecutive either) she does not qualify as a full time student.
Finally, for a student that was enrolled for that final senior year semester that graduated on May 1, you get to count the entire month of May as one of the 5 months. But if their grad date was Apr 30th, then you only have 4 months as a full time student.
