The earned income tax credit worksheet states 2019 earned income to calculate a higher amount, but it automatically transfers over the 2020 amount.  It does allow you to manually put in the 2019.

I have looked all over and cannot find the scenario that best describes my clients situation.  If the taxpayer used the 2019 income on the 2020 tax return to calculate the eitc, can it be used again for tax year 2021.