Налогоплательщики ждут

E-file if you can, especially if you expect a refund.

In that connection the IRS says:

What You Can Expect

As of March 5, 2021, we had 2.4 million individual tax returns received prior to 2021 in the processing pipeline. Including current year returns, as of March 5, 2021, we had 9.2 million unprocessed returns in the pipeline. [...]

E-filing your 2020 tax return: To e-file you will need to enter your AGI from your tax year 2019 tax return. If your 2019 return has not yet been processed, you may enter $ 0 (zero) as your prior year Adjusted Gross Income. If you used the Non-Filers: Enter Payment Info Here tool last year to register for an Economic Impact Payment, enter “$1” as your prior year AGI. See Claiming the Recovery Rebate Credit if you aren’t required to file a tax return.