What do you believe is the single most important factor driving up the cost of living in Nigeria?

The benefit is scheduled to expire at the end of 2025 along with the other individual provisions of the 2017 Tax Cuts and Jobs Act. If it expires, the estate and gift tax exemption will fall by about half. Individuals will only be able to gift about $6 million to $7 million, and that rises to $12 million to $14 million for couples. Any assets transferred above those amounts will be subject to the 40% transfer tax.

The scheduled "sunset" of a generous provision in the estate tax next year has taken on new urgency as the odds of a divided government or Democratic president have increased, tax experts say. Under current law, individuals can transfer up to $13.61 million (and couples can send up to $27.22 million) to family members or beneficiaries without owing estate or gift taxes.

The tightening presidential race has touched off a wave of tax planning by ultra-wealthy investors, especially given fears of a higher estate tax, according to advisors and tax attorneys.

Wealth advisors and tax attorneys said expectations of a Republican sweep in the first half of the year led many wealthy Americans to take a wait-and-see approach, since former President Donald Trump wants to extend the 2017 tax cuts for individuals.

Vice President Kamala Harris has advocated higher taxes for those those making more than $400,000.

• Read More