If you contributed more for 2017 than is permitted to be deducted and you do not obtain a return of contribution (not a regular distribution) by the due date of your tax return to correct the excess, you must file Form 5330 and pay a 10% penalty (section 4972 excise tax) on the excess. You can then treat the excess as part of your contribution for 2018. TurboTax does not support Form 5330.
Form 5330: https://www.irs.gov/pub/irs-pdf/f5330.pdf
Instructions for Form 5330: https://www.irs.gov/pub/irs-pdf/i5330.pdf
