You cannot enter your form 1098-T from 2015 on your 2016 tax return.
If you did not enter this 2015 form on your 2015 tax return, then you'll need to amend your 2015 tax return to claim your education expenses.
Please read this TurboTax FAQ on how to amend your 2015 tax return:
https://ttlc.intuit.com/replies/3288565
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