The Buffett-Gates Giving Pledge, under which wealthy individuals promise to leave a majority of their assets to charity, is an admirable effort to encourage philanthropy. However, the Pledge requires us to confront the paradox that the federal estate tax charitable deduction is unlimited while the federal income tax charitable deduction is capped. If a Giving Pledger leaves his wealth to charity, the federal fisc loses significant revenue since the Pledger thereby avoids federal estate taxation as charitable bequests are deductible without limit for federal estate tax purposes. Despite its laudable qualities, the Giving Pledge is a systematic (albeit inadvertent) threat to the estate tax base.

The Giving Pledge requires the amendment of the federal estate tax to restrict an estate’s charitable deduction to a percentage of the estate, just as the income tax charitable deduction is limited to a percentage of the taxpayer’s income. In this fashion, the sensible compromise embedded in the income tax charitable deduction would be carried over to the federal estate tax to simultaneously encourage charitable giving while ensuring that all large estates pay some federal estate tax.

The Giving Pledge need not be the death knell of the estate tax. It should instead be the catalyst to reform the tax by limiting the estate tax charitable deduction.