Calculate the portion of the distribution that applies to the child and subtract that portion from the taxable portion of the CSF 1099-R.
Retain your calculation with your paper records that support your tax return should a tax authority have a question at a later time.
IRS Publication 721, page 26, states:
Surviving spouse with child
If the survivor benefits include both a life annuity for the surviving spouse and one or more temporary annuities for the retiree's children, the tax-free monthly amount that would otherwise apply to the life annuity must be allocated among the beneficiaries. To figure the tax-free monthly amount for each beneficiary, multiply it by a fraction. The numerator of the fraction is the beneficiary's monthly annuity, and the denominator of the fraction is the total of the monthly annuity payments to all the beneficiaries.
Calculate the portion of the distribution that applies to the child and subtract that portion from the taxable portion of the CSF 1099-R.
Retain your calculation with your paper records that support your tax return should a tax authority have a question at a later time.
IRS Publication 721, page 26, states:
Surviving spouse with child
If the survivor benefits include both a life annuity for the surviving spouse and one or more temporary annuities for the retiree's children, the tax-free monthly amount that would otherwise apply to the life annuity must be allocated among the beneficiaries. To figure the tax-free monthly amount for each beneficiary, multiply it by a fraction. The numerator of the fraction is the beneficiary's monthly annuity, and the denominator of the fraction is the total of the monthly annuity payments to all the beneficiaries.