The Consolidated Appropriations Act (CAA) was signed into law on December 27, 2020 as a stimulus measure to provide relief to those affected by the pandemic. For tax year 2020, the CAA allows taxpayers to use their 2019 earned income if it was higher than their 2020 earned income in calculating the Additional Child Tax Credit (ACTC) as well as the Earned Income Tax Credit (EITC).
You would NOT use your EIC amount from your 2019 tax return to calculate the amount of the credit in 2020. It simply allows you to use the 2019 income instead of 2020 if it is more beneficial for you to do so. TurboTax will calculate this for you.
Here is a TurboTax article about the EIC.
