“Portability” is a significant development in federal estate tax law. In essence, if a spouse dies and has not used all of his or her federal estate tax exclusion amount, the unused portion can be rolled over and used in the surviving spouse’s estate. Unfortunately, portability is not self-executing. It requires making an affirmative election on a timely filed federal estate tax return using IRS Form 706 regardless of the size of the first spouse’s gross estate. Even “medium” sized estates should consider making this election by filing a Form 706 as an “insurance policy” just in case the surviving spouse realizes a windfall or the federal estate tax exclusion is reduced during the lifetime of the surviving spouse.