I can answer my own question now....since I called for TT support. The 1098 includes billing for Spring of 2018 and our 529 withdraws covers only 2017 expenditures. On one child we actually only paid $2500 out of our own pocket for tuition/books in 2017 (because the scholarships paid the rest and our 529 paid room and board) but for tax purposes the numbers come out more than the $4000 needed to get the $2500 tax credit. If a student goes to school for 4 years he or she is actually billed over 5 tax years and he or she only has 4 tax years to collect the credit. So, there is some carryover (2018 is carried over a bit into our 2017 bill) . I Wish I could explain better, but it does make sense to me now. That is why the box 7 on the 1098 is checked.
