https://www.irs.gov/businesses/gifts-from-foreign-person

Reporting Requirements
You must file Form 3520, Annual Return to Report Transactions with Foreign Trusts and Receipt of Certain Foreign Gifts, if, during the current tax year, you treat the receipt of money or other property above certain amounts as a foreign gift or bequest.  Include on Form 3520:

• Gifts or bequests valued at more than $100,000 from a nonresident alien individual or foreign estate (including foreign persons related to that nonresident alien individual or foreign estate);

or

• Gifts valued at more than $15,601 for 2015 (adjusted annually for inflation) from foreign corporations or foreign partnerships (including foreign persons related to the foreign corporations or foreign partnerships).