@f404
The deadline to make a corrective distribution for 2019 deferred wages was April 15, 2020. Although this IRS document is an audit guide rather than an instruction, it contains the same information.
https://www.irs.gov/retirement-plans/consequences-to-a-participant-who-makes-excess-deferrals-to-a-4...
Since you can't make a corrective distribution, the excess deferral is taxed on your 2019 tax return AND your withdrawals will be taxed, you do not get a basis in the 401(k). In this way, a 401(k) plan is quite different from an IRA, where making non-deductible contributions gives you a basis in future withdrawals.
Please tell me where you are seeing a 6% additional penalty in reference to a 401(k) excess deferral. This is subject to much confusion because IRAs have a 6% penalty for excess contributions but a 401(k) is not an IRA, they are covered under completely different tax codes even though their overall purpose is similar. I see several internet articles (and even a few other answers on this forum, unfortunately) that get the two confused. Further, the rules that limit deferrals by "highly compensated employees" apply to the plan, not to the individual. The plan may be required to return your excess contributions if you are subject to a reduced limit as an HCE, but that burden is not on you. There is no additional 6% penalty for uncorrected excess deferrals as far as I can tell. If there was, it would be calculated on form 5329, which does not have a section for excess deferrals to a 401(k). @dmertz is my go-to expert, in case they want to weigh in further.
https://www.irs.gov/pub/irs-pdf/f5329.pdf
Remember that excess contributions to an IRA are covered by completely different rules than excess deferrals to a 401(k).
Bottom line: it is too late to make a corrective distribution for 2019. The excess deferral is added to your box 1 taxable wages and you pay income tax on it. There are no further taxes or penalties. Then, when you withdraw the money in retirement, all your distributions will be subject to regular income tax, even though a portion of your contributions were already taxed.
As to how to report the excess deferral on your 2019 tax return, print your return before you file and double check. I would expect that turbotax would advise you to take a corrective distribution before April 15, 2020, and if you indicate you can't or won't do it, turbotax would automatically add the income to line 1. Therefore, I expect that adding more income to line 1 will result in a double entry. I may be wrong about how Turbotax works in this situation. So, before you mail your return, print it and review it carefully, and make sure that the total taxable income on line 1 is correct; it should be job 1 plus job 2 plus the excess deferral, but the excess deferral should not be doubled.
