Yes, you are correct. Interest and Capital Gains are not reportable unless they are effectively connected with a US business. Capital Gains are not taxable either unless the partner stayed in the US for 183 days during the tax year.
If these conditions are met, the income isn't taxable nor a 1042 S would be issued because there were no withholdings to be made. If dividends were paid however, then this is taxable income and withholding tax would need to be withheld at 30%. This would then be reported on a 1042 S.
This IRS document explains this well.
@yuan60101
**Say "Thanks" by clicking the thumb icon in a post
**Mark the post that answers your question by clicking on "Mark as Best Answer"
