TurboTax determines whether any part of a Roth IRA contribution is an excess contribution only after you enter the proposed contribution. After having completed all other aspects of your tax return, enter the maximum permissible contribution for your age, allow TurboTax to tell you you if any of that is an excess contribution, then go back and change the amount of your proposed Roth IRA contribution, reducing it by the amount that was determined to be excess.
