I think you are talking about two different things. The original question seems to be the calculation of a deduction for Income in Respect of a Decedent because the deceased's estate was subject to estate taxes. A deduction can be taken for IRD up to the beneficiary's portion of the estate tax paid.
To enter the deduction, go to Deductions & Credits -> Other Deductions and Credits -> Other Deductible Expenses. Answer No to Generation Skipping Taxes and to Less Common Expenses. Answer Yes to Any Other Deductions. Enter the deduction for IRD in the box labeled Estate Tax Deduction.
