The 1040-NR is a tax form used by non-resident aliens in the United States to report their income and calculate their tax liability. This form is specifically designed for individuals who do not meet the criteria to be considered residents for tax purposes, such as foreign students, scholars, and certain workers. Non-resident aliens must file the 1040-NR if they have U.S.-sourced income or if they are engaged in a trade or business in the U.S. The form helps the Internal Revenue Service (IRS) assess the correct amount of tax owed based on the income earned during the tax year.