A dual-status alien is a person who was both a resident alien and a nonresident alien for US tax purposes in the same tax year, which usually happens in the year of arrival in or departure from the United States. The year splits at a date, and the two parts are taxed under two different sets of rules.
The status is not a filing election and it is not about citizenship. It follows from the residency tests landing on different answers at the start and the end of the same year.
The Year Is Treated as Two Periods
The regulation states the split in both directions and says what it does.
An individual who is a citizen or resident of the United States at the beginning of the taxable year but a nonresident alien at the end of it, or a nonresident alien at the beginning but a citizen or resident at the end, is taxable for such year as though his taxable year were comprised of two separate periods, one consisting of the time during which he is a citizen or resident of the United States and the other consisting of the time during which he is not (26 CFR 1.871-13(a)(1)). The same paragraph then closes a loop most summaries leave open. In determining the taxable income for such year which is subject to the graduated rate of tax imposed by section 1 or 1201 of the Code, all income for the period of US citizenship or residence must be aggregated with the income for the period of nonresidence which is effectively connected for such year with the conduct of a trade or business in the United States.
Two periods, then, but one graduated rate schedule run over a combined base.
The regulation also fixes which side of the line the changeover day falls on. For purposes of that section, an individual is deemed to be a citizen or resident of the United States for the day on which he becomes a citizen or resident of the United States, a nonresident of the United States for the day on which he abandons his US residence, and an alien for the day on which he gives up his US citizenship (26 CFR 1.871-13(a)(2)).
And it names who is outside it. The section does not apply to alien individuals treated as residents for the entire taxable year under section 6013(g) or (h), who are taxed under the rules in 1.1-1(b) instead (26 CFR 1.871-13(a)(1)). A married couple that elects to treat the nonresident spouse as a resident for the whole year has therefore switched the dual-status treatment off rather than worked around it, and the publication says the same from its own side: for someone married who chooses to be a nonresident spouse treated as a resident, the rules of the dual-status chapter do not apply for that year (IRS, Publication 519 (2025)).
Where the Line Falls
The split date is not chosen. It comes out of the same residency tests set out in nonresident alien.
Arriving. Someone who is a US resident for the calendar year but was not a US resident at any time during the preceding calendar year is a US resident only for the part of the year beginning on the residency starting date, and a nonresident alien for the part before it. Under the substantial presence test that starting date is generally the first day of presence in the United States during that calendar year, and up to 10 days of actual presence do not have to be counted where, on those days, the person establishes both a closer connection to a foreign country than to the United States and a tax home in that foreign country (IRS, Publication 519 (2025)). The same publication adds the limb that catches people out: although up to 10 days can be excluded in determining the residency starting date, those days must still be included when determining whether the substantial presence test is met at all.
Leaving. Someone who was a US resident in a year but is not a US resident during any part of the following year ceases to be a resident on the residency termination date, which is December 31 unless an earlier date is available. The earlier date is the last day of physical presence in the United States for someone who met the substantial presence test, the first day of no longer being a lawful permanent resident for someone who met the green card test, or the later of the two for someone who met both, and it can be used only where, for the remainder of the year, the tax home was in a foreign country and there was a closer connection to that country (IRS, Publication 519 (2025)).
What Each Period Taxes
For the resident part of the year, income from all sources is taxed, and foreign source income is taxable if it is received while a resident alien, even if it was earned while a nonresident alien or the person became a nonresident alien after receiving it and before the end of the year (IRS, Publication 519 (2025)).
For the nonresident part, the reach is narrower: US source income, plus certain foreign source income treated as effectively connected with a US trade or business. Foreign source income that is not effectively connected is not taxable if it is received while a nonresident alien, and it stays untaxed even if it was earned while a resident alien, or the person became a resident alien or a US citizen after receiving it and before the end of the year (IRS, Publication 519 (2025)).
So receipt, not merely when the work was done, is doing the work in both halves. That is the practical reason the split date matters more than it looks.
Which Form Is the Return and Which Is the Statement
Both forms are involved either way, and the last day of the tax year decides which one is which.
A dual-status taxpayer who becomes a resident during the year and is a US resident on the last day of the tax year files Form 1040 or 1040-SR, checks the Other checkbox at the top and writes Dual Status Return on the entry line, and attaches a statement showing the income for the nonresident part of the year, for which Form 1040-NR can be used, marked Dual Status Stmt (IRS, Publication 519 (2025)).
A dual-status taxpayer who gives up residence during the year and is not a US resident on the last day of the tax year does the reverse: Form 1040-NR is the return, and Form 1040 or 1040-SR can be used as the statement showing the income for the resident part (IRS, Publication 519 (2025)).
Two mechanical points carry explicit year qualifiers rather than standing rules. The Other checkbox was added on Forms 1040, 1040-SR and 1040-NR for 2025, and dual-status taxpayers cannot e-file their US income tax return for tax year 2025 (IRS, Publication 519 (2025)).
The Restrictions That Apply to the Return
Four restrictions apply to a return filed for a dual-status tax year, and each has a limb worth keeping (IRS, Publication 519 (2025)).
- The standard deduction is out, itemizing is not. The standard deduction allowed on Form 1040 or 1040-SR cannot be used, but any allowable deductions can still be itemized. What the standard deduction otherwise does is in standard deduction.
- Head of household. The head of household Tax Table column or Tax Computation Worksheet cannot be used.
- No joint return, subject to the choosing-resident-alien-status route the publication points to in its own chapter 1.
- Rate column. Someone married and a nonresident of the United States for all or part of the year who does not choose to file jointly must use the married filing separately Tax Table column or Tax Computation Worksheet on income effectively connected with a US trade or business, and cannot use the married filing jointly or single columns. Filing as single may be possible for someone who lived apart from their spouse during the last 6 months of the year and is a married resident of Canada, Mexico or South Korea, or a married US national.
What a Dual-Status Alien Is Not
- Not a dual citizen. Dual status does not refer to citizenship, only to US tax resident status (IRS, Publication 519 (2025)).
- Not a dual-resident taxpayer. That is a separate term with its own mechanism. A dual-resident taxpayer claiming treaty benefits files a return using Form 1040-NR with Form 8833 attached and computes tax as a nonresident alien (IRS, Publication 519 (2025)), rather than splitting a year in two.
- Not a permanent condition. It describes one tax year. The year before and the year after are each decided on their own, through the tests in nonresident alien.
Common Questions
Anyone who was both a resident alien and a nonresident alien in the same tax year. In practice that is almost always the year of arrival or the year of departure, because those are the years in which the residency tests change their answer partway through.
No. The standard deduction allowed on Form 1040 or 1040-SR is unavailable for a dual-status tax year, though allowable deductions can be itemized instead.
The one that matches the status on the last day of the tax year. Resident on that day means Form 1040 or 1040-SR as the return with Form 1040-NR attached as the statement, and nonresident on that day means the opposite. Both are marked, one Dual Status Return and one Dual Status Stmt.
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