Six-Month Estate Valuation Window Slashes Tax When Markets Fall

Only estates that owe federal estate tax qualify. Congress wrote a hard gate: the election is permitted only if it reduces both the value of the gross estate and the estate tax liability. For decedents dying in 2026, the basic exclusion amount is $15 million, up from $13.99 million for 2025 estates. That number means most families never file Form 706. The alternate valuation date is a tool for taxable estates and those with concentrated equity positions.

The mechanics are straightforward. Take a snapshot of every asset in the gross estate as of the date of death. Watch the portfolio for six months. If markets slide or a concentrated holding takes a real hit, run the numbers under both scenarios. Assets sold, exchanged, or distributed inside the six-month window are valued as of the disposition date, not the six-month mark. Confirm the election lowers both the gross estate value and the tax due. Make the election on a timely filed Form 706, generally due nine months after death unless an extension is filed. Miss the deadline and the door closes. The election cannot be made on a late return.

The tradeoff is significant, estate planning attorneys said. A lower estate valuation means a lower stepped-up basis for beneficiaries. When they eventually sell that inherited stock or property, their capital gain is measured against the alternate valuation, not the higher date-of-death price. The estate saves tax today at 40%, heirs may face a larger capital gains bill later. In a market that then rebounded, as it did after the March 2026 spike, the numbers can flip. The S&P 500 is up 14.07% year to date through August 13, 2026.

This is an executor-level decision. The math is fact-specific to each estate. Run it with a qualified estate attorney or CPA before signing the return.