U.S. Estate and Gift taxes are considered "transfer" taxes and not "income" taxes and the tax is asserted against the person making the transfer. The U.S. Estate and Gift taxes apply differently to U.S. persons and non-U.S. persons, and some of the rules depend on if the non-U.S. person is considered a resident (which are not the same as traditional income tax rules.)
For an introduction to U.S. estate and gift tax see the following links:
- An Explanation of U.S. Estate 7 Gift Tax: U.S. and Non-U.S. Persons by Angloinfo, includes links to important IRS forms
- IRS Introduction to Estate and Gift Taxes, Publication 950
- Gift Tax Audits Increasing by Angloinfo
Looking for help? Start with the Society of Trust and Estate Practitioners.