Generally, these are interrelated computations where section 6166 is not involved. Amounts to be distributed to a surviving spouse (section 2056) or a charity (section 2055) are interrelated with the Federal estate tax and some of the expenses that are deductible on Schedules J and K of the estate tax return. Each case is unique. Given the escalated level of complexity that is possible (e.g., combining interrelated marital and charitable deductions with a New York elective share computation, where charges are allocated among the estate and several trusts), in order to generate a correct computation the specific scheme of distribution and allocation of charges must be verified with counsel for the estate at each step in the computation process.

After an interrelated estate tax charitable deduction computation has been completed, a companion section 664 computation can also be run for income tax purposes.