529 earnings being taxed?

When I input a 1099-Q for distributions for my daughter's college tuition, TurboTax starts out by calculating a tax on the earnings. That's expected, but when I go to enter the matching expenses, it won't let me saying my income exceeds the maximum limit, which makes sense if I had wanted to claim those expenses directly, but I simply want to offset the amount distributed under the 1099-Q. Did the law change or am I doing something wrong?