Minor Beneficiary: Tax Reporting

[Guest 4Kicks]

Death distribution: minor beneficiary. We received the paperwork regarding the custodian and we know how the check needs to be made payable: Adult Name Custodian of Child Name Minor (they did not elect inherited IRA - they want lump sum distribution). We know it is subject to mandatory withholding as it is considered an eligible rollover distribution.

I'm sure this is an easy question but I can't find a concrete answer:how is the tax reporting done for the withholding? I've read that the beneficiary is liable for the income taxes of the distribution - does this mean the tax reporting is on the minor child, therefore we need her social security #? Or is the tax reporting on the adult custodian and we need his social security #?