Is 2020 tax return based on 2019 income?

[xmasbaby0]

No.   A 2020 tax return is what you use to report your 2020 income.   You prepare and file a 2020 return in 2021, now that the tax year 2020 is over.   All of the tax documents you enter on your 2020 return should say 2020 on them---like your W-2's, 1099's etc.   You cannot enter income from any other year on a 2020 tax return.   The current online software is only for 2020 returns----no other year.

[VolvoGirl]

Why are you asking?  You do need to enter the 2019 AGI to efile 2020.  Or There is a lookback to 2019 to qualify for the EIC.

The special lookback rule will allow lower income individuals to use their earned income from 2019 to determine their Earned Income Tax Credit and the refundable portion of the Child Tax Credit in 2020, since their lower 2020 income could reduce the amount they are eligible for.

You may use your 2019 income for the Child Tax Credit if your 2019 earned income was morethan your 2020 earned income.  If your 2020  income was more than your 2019 income then you cannot use the 2019 income.