Which form is used to report transactions with foreign trusts?

Form 3520 is specifically designed for reporting transactions with foreign trusts, along with certain transactions with foreign estates and gifts. When a U.S. person has certain relationships with a foreign trust, such as being a grantor or beneficiary, or if they engage in certain transactions with the foreign trust, they must report these activities using Form 3520. This form helps the IRS track the assets and income held in foreign trusts to ensure compliance with tax laws.

The other forms provided in the options pertain to different reporting requirements. For instance, Form 1099-DIV is used to report dividends and distributions from U.S. corporations and mutual funds, while Form 8814 is for reporting the child's unearned income. Additionally, Form TD F 90-22.1, also known as the Foreign Bank and Financial Accounts Report (FBAR), is used to report foreign bank accounts, but it does not focus specifically on foreign trusts. Therefore, Form 3520 is the correct choice for reporting transactions involving foreign trusts.