Editing Form 1040 (section)

=== Who must file? ===

Form 1040 (or a variant thereof) is the main tax form filed by individuals who are deemed residents of the United States for tax purposes. The corresponding main form filed by businesses is [[Form 1120]], also called the U.S. Corporation Income Tax Return.<ref name=f1120>{{cite web|url = https://www.irs.gov/pub/irs-pdf/f1120.pdf|title = Form 1120, U.S. Corporation Income Tax Return|access-date = January 1, 2016}}</ref>

An individual is considered a resident of the United States for tax purposes if he or she is a citizen of the United States or a resident alien of the United States for tax purposes.<ref name="f1040_2014ins">{{cite web|url=https://www.irs.gov/pub/irs-pdf/i1040gi.pdf|title=1040 Instructions 2018|website=IRS|publisher=Internal Revenue Service|url-status=live|archive-url=https://web.archive.org/web/20190831171656/https://www.irs.gov/pub/irs-pdf/i1040gi.pdf|archive-date=August 31, 2019|access-date=September 7, 2019}}</ref>{{rp|6}} An individual is a resident alien of the United States if he or she passes either the [[Substantial Presence Test]] or the [[Green Card Test]], although there are also some other cases; individuals who have taxable income in the United States but fail the criteria for being resident aliens must file as nonresident aliens for tax purposes.<ref name="alien_tax">{{cite web |url=https://www.irs.gov/pub/irs-pdf/p519.pdf |archive-url=https://web.archive.org/web/20030606025620/http://www.irs.gov/pub/irs-pdf/p519.pdf |archive-date=2003-06-06 |url-status=live |title=U.S. Tax Guide for Aliens For use in preparing 2014 Returns |publisher=Internal Revenue Service}}</ref>{{rp|3}} While residents of the United States for tax purposes file Form 1040, nonresident aliens must file Form 1040NR or 1040NR-EZ.<ref>{{cite web |url=https://www.irs.gov/Individuals/International-Taxpayers/Aliens---Which-Form-to-File |title=Aliens - Which Form to File |publisher=Internal Revenue Service |access-date=December 31, 2015 |archive-date=February 7, 2016 |archive-url=https://web.archive.org/web/20160207105204/https://www.irs.gov/Individuals/International-Taxpayers/Aliens---Which-Form-to-File |url-status=live }}</ref> There is also a "dual status alien" for aliens whose status changed during the year.

Resident aliens of the United States for tax purposes must generally file if their income crosses a threshold where their taxable income is likely to be positive, but there are many other cases where it may be legally desirable to file. For instance, even if not required, individuals can file a return in order to receive a refund on withheld income or to receive certain credits (e.g. [[earned income tax credit]]).<ref name="f1040_2014ins" />{{rp|6}}