You must file 2016 Form 5329 to report and pay the 6% penalty on the excess for 2016. If you are not able to apply that excess as a Roth IRA contribution for 2017, you must do the same for 2017. If the entire excess could not be applied as a 2017 contribution (eliminating the excess in 2017), 2018 TurboTax will prepare 2018 Form 5329 for this excess carried into 2018 and include it with your 2018 tax return.
If the excess could not be applied as a 2017 or 2018 contribution, the excess carries into 2019. If you cannot apply this excess as a 2019 contribution you must obtain a regular distribution equal to the amount of the excess (with no adjustment for investment gain or loss) before the end of 2019. That will eliminate this excess for 2019 and beyond.
