Should I file Form 1040 or Form 1040NR as a newcomer to the U.S.?

File Form 1040 if you're a resident alien for the year, and Form 1040NR if you're a nonresident alien. Resident aliens (those who meet the green-card test or Substantial Presence Test) use the same 1040 as citizens, report worldwide income, and get the standard deduction—$15,000 single or $30,000 married filing jointly for 2025. Nonresident aliens use 1040NR, report only U.S.-source and effectively connected income, and usually can't take the standard deduction. In an arrival or departure year you may have a dual-status return that combines elements of both. Choosing the wrong form is a common newcomer mistake that can cost you deductions or trigger IRS notices. Determine your residency status first using the tests, then the correct form follows. If your year is mixed, read the dual-status rules before you start.