If you are a U.S. person who received foreign gifts of money or other property, you may need to report these gifts on Form 3520, Annual Return to Report Transactions with Foreign Trusts and Receipt of Certain Foreign G.... Form 3520 is an information return, not a tax return, because foreign gifts are not subject to income tax. However, there are significant penalties for failure to file Form 3520 when it is required.
See https://www.irs.gov/businesses/gifts-from-foreign-person for more in depth information.
