有两个triggers

一个是一万块或以上，银行需报告：

Under the Bank Secrecy Act (BSA) of 1970, financial institutions are required to report certain transactions to the IRS. This includes wire transfers over $10,000, which are subject to reporting under the Currency and Foreign Transactions Reporting Act (31 U.S.C. 5311 et seq.).

Financial institutions must file a Currency Transaction Report (CTR) for any transaction over $10,000. The CTR includes information about the person initiating the transaction, the recipient, and the nature of the transaction. The purpose of this requirement is to prevent money laundering and other criminal activity.

另一个是收礼人十万块或以上需报告：

You are required to report the receipt of foreign gifts or bequests only if the applicable threshold is exceeded. For purposes of determining the reporting thresholds, you must aggregate gifts received from related parties. See the Instructions to Part IV of Form 3520 for more information; see also Section VI of Notice 97-34PDF.

• For gifts or bequests from a nonresident alien or foreign estate, you are required to report the receipt of such gifts or bequests only if the aggregate amount received from that nonresident alien or foreign estate exceeds $100,000 during the taxable year. If the gifts or bequests exceed $100,000, you must separately identify each gift in excess of $5,000.

总结：外国来的大笔钱如果是wire transfer, 极其麻烦。抛开国内对汇款的严控不说。