Order Code RS21732
Updated January 18, 2007
Federal Taxation of Aliens Working in the
United States
Erika Lunder
Legislative Attorney
American Law Division
Summary
As Congress considers immigration reform, one question that often arises is
whether illegal aliens and other foreign nationals working in the United States are
subject to U.S. taxes. The federal tax consequences for these individuals are dependent
on (a) whether an individual is classified as a resident or nonresident alien and (b)
whether a tax treaty or agreement exists between the United States and the individual’s
home country. Resident aliens are generally taxed in the same manner as U.S. citizens.
Nonresident aliens are subject to different treatment, such as generally being taxed only
on income from U.S. sources. Exceptions from the general rules may exist for aliens
with specific types of visas or employment, and the provisions of a tax treaty or
totalization agreement may reduce or eliminate taxes owed to the United States.
Immigration Status
This report discusses the federal tax treatment of alien individuals (i.e., foreign
nationals) who are working in the United States. Under U.S. immigration law, foreign
nationals are legally admitted into the United States as immigrants to live permanently or
as nonimmigrants to stay on a temporary basis.1 The terms “immigrant” and
“nonimmigrant” are not used in the Internal Revenue Code. Instead, as discussed below,
a foreign national, whether in the United States as an immigrant, nonimmigrant or illegal
alien, is classified as a resident or nonresident alien for federal tax purposes.
Certain exceptions to the tax laws exist for aliens with specific visa types. These
exceptions are almost exclusively for F-, J-, M-, and Q-visa holders who are temporarily
admitted into the United States as foreign students, teachers, trainees, and cultural
1 For more information, see CRS Report RS20916, Immigration and Naturalization
Fundamentals, and CRS Report RL31512, Visa Issuances: Policy, Issues, and Legislation, both
by Ruth Ellen Wasem.

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exchange visitors.2 Exceptions also exist for employees of foreign governments, business
visitors and tourists, aliens in transit through the United States, crew members of ships
and aircraft, and employees of international organizations. While these individuals are
usually admitted into the United States under certain visas (A-, B-1 and B-2, C-, D-, and
G-visas, respectively), they generally qualify for the exceptions based on their type of
employment, not visa category.
Resident or Nonresident Alien
For federal tax purposes, alien individuals are classified as resident or nonresident
aliens.3 The classification has important consequences for determining whether income
is subject to U.S. taxation, what is the appropriate tax rate, and whether an individual is
covered by a tax treaty. In general, an individual is a nonresident alien unless he or she
meets the qualifications under either residency test:
! Green card test: the individual is a lawful permanent resident of the
United States at any time during the current year (i.e., has an alien
registration card), or
! Substantial presence test: the individual is present in the United States for
at least 31 days during the current year and at least 183 days during the
current year and previous two years. For computing the 183 days, a
formula is used that counts all the qualifying days in the current year, 1/3
of the qualifying days in the immediate preceding year, and 1/6 of the
qualifying days in the second preceding year.4
There are several situations in which an individual may be classified as a nonresident
alien even though he or she meets the substantial presence test. For example, an
individual will be treated as a nonresident alien if he or she has a closer connection to a
foreign country than to the United States, maintains a tax home in the foreign country, and
is in the United States for fewer than 183 days during the year.5 Another example is that
an individual in the United States under an F-, J-, M-, or Q-visa may be treated as a
nonresident alien if he or she has substantially complied with visa requirements.6 Other
2 The visa letter is derived from the subparagraph of section 101(a)(15) of the Immigration and
Nationality Act that describes the type of visa. For further information, see CRS Report
RL31381, U.S. Immigration Policy on Temporary Admissions, by Ruth Ellen Wasem.
3 It is possible for an individual to be a resident alien and a nonresident alien during the same
year. For an explanation of the rules on determining residency starting and termination dates and
dual-status filing, see IRS Publication 519: U.S. Tax Guide for Aliens.
4 I.R.C. §§ 7701(b)(1)(A) and (b)(3). A nonresident alien may qualify to be treated as a resident
alien if the substantial presence test is met in the year following the election. I.R.C. § 7701(b)(4).
A dual-status or nonresident alien married to a U.S. citizen or resident may qualify to be treated
as a resident alien for the entire year. I.R.C. §§ 6013(g) and (h).
5 I.R.C. § 7701(b)(3)(B).
6 I.R.C. § 7701(b)(5). There are limits on how long an individual may be exempt from the
substantial presence test. Non-student J-, M-, or Q-visa holders are exempt for two or four years
(continued...)

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individuals that may be treated as nonresident aliens even if they meet the substantial
presence test include employees of foreign governments and international organizations,
regular commuters from Canada or Mexico, aliens who are unable to the leave the United
States because of a medical condition, foreign vessel crew members, aliens in transit
through the United States, and athletes participating in charitable sporting events.7
A residency definition in an income tax treaty will override these residency rules.
If an individual is defined as a resident of a foreign country under a treaty, then he or she
is a nonresident alien for purposes of determining his or her U.S. tax liability regardless
of whether the “green card” or “substantial presence” test is met.8
Illegal Aliens. The Internal Revenue Code does not have a special classification
for individuals who are in the United States without authorization. Instead, the Code
treats these individuals the same as other foreign nationals — they are subject to federal
taxes and classified for tax purposes as either resident or nonresident aliens. An
unauthorized individual who has been in the United States long enough to qualify under
the “substantial presence” test is classified as a resident alien; otherwise, the individual
is classified as a nonresident alien. This classification is for tax purposes only and does
not affect the individual’s immigration status.
Taxation of Income
Resident Aliens. Resident aliens are subject to the same federal income tax laws
as citizens of the United States.9 Like U.S. citizens, resident aliens are subject to tax on
all income earned in the United States and abroad. Resident aliens file a tax return using
the Form 1040 series, may claim deductions and credits, and are taxed at the same
graduated rates as U.S. citizens. They are also subject to the income tax withholding
requirements.
Nonresident Aliens. Nonresident aliens are taxed on income from sources within
the United States but generally not on income from foreign sources. Sections 861, 862,
863, 864, and 865 of the Internal Revenue Code define income that is from sources within
and outside the United States. Compensation for services performed in the United States
is U.S. source income.10
6 (...continued)
in a six-year period, depending on their source of income. After five years, student F-, J-, M-,
or Q-visa holders must establish to the IRS that they do not intend to permanently reside in the
United States in order to continue to be exempt.
7 I.R.C. §§ 7701(b)(3)(D), (b)(5), and (b)(7).
8 Treas. Reg. § 301.7701(b)-7.
9 Resident aliens who are employees of foreign governments and international organizations may
qualify to exempt their compensation from taxation. I.R.C. § 893.
10 I.R.C. § 861(a)(3).

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A nonresident alien’s U.S. source income is taxed at different rates depending on
whether it is “effectively connected” with a trade or business in the United States.11
“Effectively connected” income is income received while engaging in a trade or business
in the United States.12 It includes compensation for the performance of personal services
in the United States. Nonresident aliens with F-, J-, M-, or Q-visas are considered to be
engaged in a trade or business in the United States.13
Income that is effectively connected with a trade or business in the United States is
generally taxed by the same rules and at the same graduated rates as the income of U.S.
citizens and resident aliens.14 Income that is not effectively connected may not be reduced
by most deductions and is generally taxed at a flat rate of thirty percent.15 Nonresident
aliens file a return using the Form 1040NR series and are subject to the same collection
procedures as U.S. citizens and resident aliens. Additionally, nonresident aliens are
generally subject to withholding requirements on personal service compensation and non-
effectively connected income.16
There are limited circumstances in which a nonresident alien’s U.S. source income
is not subject to U.S. taxation. For example, some interest income that is not effectively
connected with a U.S. trade or business (e.g., foreign portfolio interest) is exempt from
U.S. tax.17 Compensation for services performed in the United States is not subject to
U.S. tax if the services are for a foreign employer or office, the alien is in the United
States for not more than 90 days during the tax year, and the compensation does not
exceed $3000.18 A nonresident alien with an F-, J-, or Q-visa is not taxed on
compensation received from a foreign employer.19 Employees of foreign governments
and international organizations and crew members of foreign vessels and aircraft may
qualify to exempt their compensation from tax.20 Furthermore, income may be exempt
from U.S. tax under a treaty (see below).
11 I.R.C. § 871.
12 I.R.C. § 864(c).
13 I.R.C. § 871(c).
14 I.R.C. §§ 871(b) and 873. Examples of nonresident aliens being subject to different rules than
U.S. citizens and residents are that nonresident aliens may not claim the standard deduction, more
than one personal exemption, or the earned income credit.
15 I.R.C. §§ 871(a) and 873.
16 I.R.C. §§ 1441 and 3402; Treas. Reg. § 1.1441-4(b)(1). The rate of withholding on
compensation for personal services is generally the applicable graduated income tax rate,
although self-employed individuals may be subject to withholding at a flat 30% rate. The rate
of withholding on non-effectively connected U.S. source income is 30% unless (a) the 14% rate
applies for qualifying income received by nonresident aliens with F-, J-, M-, and Q-visas or (b)
there is a lower rate under an income tax treaty.
17 I.R.C. §§ 871(h) and (i).
18 I.R.C. §§ 861(a)(3) and 864(b)(1).
19 I.R.C. § 872(b)(3).
20 I.R.C. §§ 861(a)(3), 872, and 893.

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Sailing Permit. Aliens leaving the United States are generally required to obtain
a certificate of compliance (“sailing permit”) from the IRS that shows the individual “has
complied with all the obligations imposed upon him by the income tax laws.”21 For aliens
who attempt to leave without obtaining the permit, the IRS may subject them to
examination at the point of departure and require payment of any tax due if its collection
would be jeopardized by the departure. Aliens that may be exempt from the permit
requirement include employees of international organizations and foreign governments;
students and trainees with F-, H-, J-, and M-visas; military trainees; visitors, including
those on B-1 or B-2 visas; aliens in transit through the United States on a C-1 visa; and
commuters from Canada and Mexico.22
Tax Treaties. Tax treaties provide benefits to nonresident aliens and, in certain
situations, resident aliens. Benefits vary by treaty and typical provisions include the
reduction of the 30% flat rate applied to non-effectively connected U.S. source income
and the exemption of gain from the sale of personal property. Treaties often exempt
personal service compensation from taxation if a nonresident individual is in the United
States for less than a stated period of time (e.g., 90, 180, or 183 days) or the compensation
is less than a specified amount (generally between $3,000 and $10,000) and paid by a
foreign employer. Additionally, the compensation of specific groups of employees (e.g.,
students, teachers, athletes, and employees of foreign governments) is often exempted
from U.S. tax.
The United States has income tax treaties with the following countries:
Australia, Austria, Bangladesh, Barbados, Belgium, Canada, China, the
Commonwealth of Independent States, Cyprus, Czech Republic, Denmark, Egypt,
Estonia, Finland, France, Germany, Greece, Hungary, Iceland, India, Indonesia,
Ireland, Israel, Italy, Jamaica, Japan, Kazakhstan, Latvia, Lithuania, Luxembourg,
Mexico, Morocco, the Netherlands, New Zealand, Norway, Pakistan, Philippines,
Poland, Portugal, Romania, Russia, Slovak Republic, Slovenia, South Africa, South
Korea, Spain, Sri Lanka, Sweden, Switzerland, Thailand, Trinidad and Tobago,
Tunisia, Turkey, Ukraine, the United Kingdom, and Venezuela.
Social Security and Medicare Taxes
Resident Aliens. Resident aliens are subject to Social Security and Medicare
taxes on wages (FICA taxes) and on self-employment income (SECA taxes) in the same
manner as U.S. citizens.23 A list of exempted services in section 3121(b) is generally
applicable to all who work in the United States. Examples include services provided by
employees of foreign governments and qualifying international organizations.
Nonresident Aliens. Nonresident aliens are subject to FICA taxes on
compensation from work within the United States under the rules applicable to U.S.
21 I.R.C. § 6851(d).
22 Treas. Reg. § 1.6851-2.
23 I.R.C. §§ 1402(b) and 3121(b).

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citizens and resident aliens.24 A list of exempted services in section 3121(b) is generally
applicable to all who work in the United States and includes services provided by
employees of foreign governments and qualifying international organizations. Some
exemptions apply only to nonresident aliens: (1) services performed by foreign workers
admitted to the United States on a temporary basis to perform agricultural labor; (2)
services performed by individuals with F-, J-, M-, or Q-visas that meet the purpose of
admittance; and (3) services performed in Guam by H-2 visa holders who are residents
of the Philippines. Nonresident aliens are generally not subject to SECA taxes.25
Totalization Agreements. The United States has entered into totalization
agreements with numerous countries that have social security programs. The intent of
these agreements is to provide individuals who work in two countries with the opportunity
to qualify for social security benefits within one country and to avoid double taxation.
Under an agreement, an alien who is sent by a foreign employer to work in the United
States for less than five years will generally not be subject to FICA taxes upon proving
that he or she is paying social security taxes to the home country.26 A self-employed
resident alien generally pays taxes in the country where he or she resides.
The United States has entered into totalization agreements with Australia, Austria,
Belgium, Canada, Chile, Finland, France, Germany, Greece, Ireland, Italy, Japan,
Luxembourg, the Netherlands, Norway, Portugal, Spain, South Korea, Sweden,
Switzerland, and the United Kingdom.27 It appears the United States has completed
negotiations with the Czech Republic and Denmark, but the agreements have not yet been
signed.28 The United States signed an agreement with Mexico on June 29, 2004, but it
has not been transmitted to Congress.29 Under 42 U.S.C. § 433(e)(2), once an agreement
is transmitted, it becomes effective at the end of the period during which at least one
House has been in session 60 days, unless either House adopts a resolution of disapproval.
It should be noted, however, that this is a legislative veto and the Supreme Court has held
such vetoes to be unconstitutional.30
24 I.R.C. § 3121(b).
25 I.R.C. § 1402(b).
26 I.R.C. §§ 1401(c), 3101(c), and 3111(c).
27 Texts of the agreements may be found on the website of the Social Security Administration at
[http://www.ssa.gov/international].
28 [http://www.ssa.gov/international/status.html].
29 The agreement with Mexico has been controversial. For more information, see CRS Report
RL32004, Social Security Benefits for Noncitizens: Current Policy and Legislation, by Dawn
Nuschler and Alison Siskin; CRS Report RL33015, Mexican Workers in the United States: A
Comparison with Workers from Social Security Totalization Countries, by Alison Siskin and
Gerald Mayer; and Social Security: Proposed Totalization Agreement with Mexico Presents
Unique Challenges, GAO-03-993 (September 2003).
30 INS v. Chadha, 462 U.S. 919 (1983).

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