The amount in boxes 1 and 2a of the code 7 2020 Form 1099-R must be the amount that you originally took out of the IRA, including the tax withholding, not some lower amount. They must not have any other value. Some or all of the distribution is made nontaxable by how you report it on your tax return, not by how it is reported on the Form 1099-R. To make the distribution entirely nontaxable you would have had to have substituted other funds for the amount withheld for taxes.
