I made a non-deductible contribution in 2020 (for a backdoor Roth IRA) but answered "No" because the instructions specified "2019 or previous". When reviewing my Form 1040 before submission, I noticed that the contribution was being added to my income (when it was withdrawn early for the conversion) when it shouldn't have been because the original contribution was non-deductible.
I went back through the questions, selected "Yes" (this time assuming they meant 2020) and everything worked out properly on my 1040.
This was extremely frustrating
