You don't enter it on tax return or in TurboTax. On form 1099-Q, instructions to the recipient reads: "Nontaxable distributions from CESAs and QTPs are not required to be reported on your income tax return. You must determine the taxability of any distribution."
So, you can just not report the 1099-Q, at all, if your student-beneficiary has sufficient educational expenses, including room & board (even if he lives at home) to cover the distribution. You would still have to do the math to see if there were enough expenses left over to claim the tuition credit. You (and/or the parents or student herself) cannot double dip", When the box 1 amount on form 1099-Q is fully covered by expenses, TurboTax will enter nothing about the 1099-Q on the actual tax forms. But, it will prepare a 1099-Q worksheet for your records..
* I assume the student is not your dependent, but is the dependent of her parents. If they plan to claim a tuition credit, they cannot use the same tuition expenses, that you use to claim the earnings exclusion on the 1099-Q. So, you have to coordinate with them. See separate reply for details.
