@aa2:
1) Yes, you must amend 2017 to include the excess withdrawal that was included on the 2018 1099-R. It is taxable income for 2017 because you were not eligible to defer it in 2017.
2) Yes, you would have had to manually adjust your wages when preparing your 2017 Tax Return to include the excess contributions as wages on your return.
3) <a rel="nofollow" target="_blank" href="
https://www.irs.gov/retirement-plans/consequences-to-a-participant-who-makes-excess-deferrals-to-a-4...>
4) TT should allow you to enter the 1099-r with Code 8, are you getting an error message?
5) No, there is nothing you can do at this point to avoid having to Amend your 2017 return
