TurboTax
uses parts of you college expenses to claim the Tuition credit. That reduces
the amount that can be used to claim the 1099-Q as being totally tax free.
If your income is too high to claim a tuition credit, see https://ttlc.intuit.com/questions/4451709-why-is-the-529-distribution-from-my-1099-q-showing-up-as-t...
