1. Only backup withholding is permitted to be passed through to estate beneficiaries. The tax withholding reported in box 4 of the Form 1099-R is almost certainly not backup withholding, so the tax withholding remains as a credit on Form 1041 and any refund will have to be paid to the estate to be subsequently distributed to the estate beneficiaries. This is why, in general, tax withholding should be declined on any retirement distributions paid to an estate. (A distribution to the estate would be subject to backup withholding only if the executor failed to provide the payer with the EIN of the estate or if the IRS had previously explicitly made the estate subject to backup withholding.)
2. The taxable amount of the distribution to be entered is the amount in box 2a of the Form 1099-R. That will be the same as the amount in box 1 if nothing is shown in box 5.
