Gift tax in the United States
If a person is a non-resident alien for purposes of gift tax, taxation of gifts is determined in a different way. If the property is not located in the U.S., there is no gift tax. If it is intangible property, such as shares in U.S. corporations and interests in partnerships or LLCs, there is no gift tax.
Estate tax in the United States
U.S. real estate owned by a non-resident alien through a foreign corporation is not included in a non-resident alien's estate. The corporation must have a business purpose and activity, lest it be deemed a sham designed to avoid U.S. estate taxes.
The estate tax of a deceased spouse depends on the citizenship of the surviving spouse.