IRS Link to Reporting Guidelines — Found Here
Despite how it sounds, this publication is not meant for tourists to the US, but rather for non-US-citizen workers who might be considered either resident aliens or nonresident aliens, or dual-status if they can be considered both within the same year.
Non resident aliens do not have to file a return if they did not earn more than the standard annual deduction amount. This guide is relatively short by IRS Publication standards, at only about 20 pages.
More information can be found in IRS Publication 519, US Tax Guide for Aliens.
Generally anyone who earns wages in the US above the standard deduction mount, whether or not they are permanent residents of the United States, will file a return with the IRS. For nonresident alien employees, this means filing a 1040NR or 1040NR – EZ.
Publication 513 can illuminate some of the questions that the workers and their employers might have. The standard deduction amount for a single filer is $6,350 in 2017 and $12,700 for a married couple filing jointly.
Most visitors to the United States will not be allowed to work here, and aliens should check first with US Citizenship and Immigration Services (USCIS). The alien may need to use a W7 to apply for a taxpayer identification number (TIN).
When an alien ends their tenure in the US and departs, a 1040-C or 2063 must be filed to “wrap-up” the individual’s tax reporting in the US. Generally a Resident Alien is subject to the same tax regulations as US citizens, while Nonresident Aliens must adhere to these different regulations described in Pub. 513, 519, and elsewhere.
Sometimes certain income is exempt due to international tax treaties.