I missed reporting a 1098-T for my oldest son, college tuition. I am getting a refund, do I need to file an amended return?

If you claim him as a dependent, the only way to get a credit or deduction for qualified education expenses (primarily tuition and fees and sometimes books and course related materials) paid out of pocket or with loans is to enter the expenses on your tax return. The 1098-T is the form to start with to enter those expenses. The credit can be up to $2500 for up to $4000 of expenses. If scholarships or grants paid for all the qualified expenses, you would not get any credit.

If the return you filed is accepted, you would need to file an amended return to enter the expenses. See this link for how to amend a return: https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed

If your son had scholarship or grant awards that paid for non qualified expenses such as room and board, he must enter that income on his tax return.