Income tax in the United States

UStaxationThe federal government of the United States imposes a progressive tax on the taxable income of individuals, partnerships, companies, corporations, trusts, decedents' estates, and certain bankruptcy estates. Some state and municipal governments also impose income taxes. The first Federal income tax was imposed (under Article I, section 8, clause 1 of the U.S. Constitution) during the Civil War, then again in the 1890s, and again after the Sixteenth Amendment was ratified in 1913. Current income taxes are imposed under these constitutional provisions and various sections of Subtitle A of the Internal Revenue Code of 1986, as amended, including usc|26|1 (imposing income tax on the taxable income of individuals, estates and trusts) and usc|26|11 (imposing income tax on the taxable income of corporations).

Income tax basics

While U.S. tax law is very complex, the underlying idea is relatively easy to understand. Simplifying greatly, gross income is all income from all sources (USCSec|26|61) less any exclusions (USCSec|26|101 et seq.). An exclusion is something that Congress has effectively said a taxpayer need not include in his or her income for tax purposes, such as employer-paid health insurance (USCSec|26|106) or interest from tax-exempt bonds (USCSec|26|103).

For individuals, Adjusted Gross Income (AGI) is gross income less any above-the-line deductions (USCSec|26|62). Above-the-line deductions are listed in USCSec|26|62 and include trade or business deductions, alimony (USCSec|26|215), and moving expenses (USCSec|26|217). Taxable income is AGI less (1) itemized deductions or the applicable standard deduction, whichever is greater, and (2) a deduction for any allowable personal exemptions for the taxpayer, the taxpayer's spouse (if filing jointly), and the taxpayer's dependents. (In certain cases involving higher income taxpayers, the allowed personal exemptions may be reduced or even eliminated.)

Non-itemizers take the standard deduction. Itemized deductions include any deduction not listed in USCSec|26|62 such as charitable contributions (USCSec|26|170) and certain medical expenses (USCSec|26|213). Taxable income is then multiplied by the appropriate tax rate to arrive at the tax due. Tax credits such as the Earned Income Tax Credit (USCSec|26|32) or the Child Tax Credit (USCSec|26|24) lower the tax owed on a dollar-for-dollar basis. This means tax credits are more valuable than deductions because deductions are applied before the tax rate while credits are applied after. For instance, with a 35% tax rate, a deduction of $100 would save only $35 of taxes while a $100 credit would save $100 worth of taxes.

Types of income

For tax purposes, income can be divided in a variety of ways. The first division is between ordinary income and capital gains. Ordinary income includes compensation for personal services such as wages and salaries, business profit, dividends from stock shares, and interest income from invested funds while capital gain generally comes from the sale of investment property. Congress has typically shown a preference for long-term investment by having a capital gains tax rate lower than the ordinary income rate. However, only long-term capital gains get preferential treatment; short-term capital gains (from property held for one year or less) are taxed at the same rate as ordinary income. Added complications come from various distinctions within each category. For instance, qualified dividends, which were previously taxed at ordinary income rates (as non qualified dividends currently are), are currently taxed at long-term capital gain rates until 2011 under the Jobs and Growth Tax Relief Reconciliation Act of 2003, and within long-term capital gains, gains on certain real estate, collectibles, and small business stock each have their own tax rates. The rules for offsetting capital losses with gains (whether capital or ordinary) add further complications. In ordinary usage, when someone speaks of their "tax rate", they typically are referring to their marginal tax rate for ordinary income.

Another important distinction in types of income is income from passive activities versus non-passive activities (USCSec|26|469), an attempt to curb tax shelters used by taxpayers not directly involved with an activity other than as an investor ("passive").

Year 2007 income brackets and tax rates

An individual's marginal income tax bracket depends upon their income and their tax-filing classification. As of 2007, there are six tax brackets for ordinary income (ranging from 10% to 35%) and four classifications: single, married filing jointly (or qualified widow or widower), married filing separately, and head of household.:* Capital gains up to $250,000 ($500,000 if filed jointly) on real estate used as primary residence are exempt.

Example of a tax computation

Income tax for year 2007:

* $40,000 (taxable income)
** $7,825 × 0.10 = $782.50
** ($31,850 - $7,825) × 0.15 = $3,603.75
** ($40,000 - $31,850) × 0.25 = $2,037.50
* Total income tax = $6,423.75 (16.06% of income assuming no deductions, exemptions or credits are taken)

Note that in addition to income tax, a wage earner would also have to pay FICA (payroll) tax (and an equal amount of FICA tax must be paid by the employer):

* $40,000 (adjusted gross income)
** $40,000 × 0.062 = $2,480 (Social Security portion)
** $40,000 × 0.0145 = $580 (Medicare portion)
* Total FICA tax = $3,060 (7.65% of income)

* Total federal tax of individual = $9,483.75 (23.71% of income)

See also Rate schedule (federal income tax)

Legal history

Article I, Section 8, Clause 1 of the United States Constitution (the "Taxing and Spending Clause"), specifies Congress's power to impose "Taxes, Duties, Imposts and Excises," but Article I, Section 8 requires that, "Duties, Imposts and Excises shall be uniform throughout the United States." [ [http://www.usconstitution.net/xconst_A1Sec8.html US Constitution.net] ]

In addition, the Constitution specifically limited Congress' ability to impose direct taxes, by requiring it to distribute direct taxes in proportion to each state's census population. It was thought that head taxes and property taxes (slaves could be taxed as either or both) were likely to be abused, and that they bore no relation to the activities in which the federal government had a legitimate interest. The fourth clause of section 9 therefore specifies that, "No Capitation, or other direct, Tax shall be laid, unless in Proportion to the Census or enumeration herein before directed to be taken."

Taxation was also the subject of Federalist No. 33 penned secretly by the Federalist Alexander Hamilton under the pseudonym Publius. In it, he explains that the wording of the "Necessary and Proper" clause should serve as guidelines for the legislation of laws regarding taxation. The legislative branch is to be the judge, but any abuse of those powers of judging can be overturned by the people, whether as states or as a larger group.

The courts have generally held that direct taxes are limited to taxes on people (variously called "capitation", "poll tax" or "head tax") and property. ["Penn Mutual Indemnity Co. v. Commissioner", 227 F.2d 16, 19-20 (3rd Cir. 1960)] All other taxes are commonly referred to as "indirect taxes," because they tax an event, rather than a person or property "per se." ["Steward Machine Co. v. Davis", ussc|301|548|1937, 581-582] What seemed to be a straightforward limitation on the power of the legislature based on the subject of the tax proved inexact and unclear when applied to an income tax, which can be arguably viewed either as a direct or an indirect tax.

Early Federal income taxes

In order to help pay for its war effort in the American Civil War, the United States government imposed its first personal income tax, on August 5, 1861, as part of the Revenue Act of 1861 (3% of all incomes over US $800; rescinded in 1872).

In 1894, Democrats in Congress passed the Wilson-Gorman tariff, which imposed the first peacetime income tax. The rate was 2% on income over $4000, which meant fewer than 10% of households would pay any. The purpose of the income tax was to make up for revenue that would be lost by tariff reductions. [ Charles F. Dunbar, "The New Income Tax," "Quarterly Journal of Economics," Vol. 9, No. 1 (Oct., 1894), pp. 26-46 [http://www.jstor.org/stable/1883633 in JSTOR] ]

In 1895 the United States Supreme Court, in its ruling in "Pollock v. Farmers' Loan & Trust Co.," held a tax based on receipts from the use of property to be unconstitutional. The Court held that taxes on rents from real estate, on interest income from personal property and other income from personal property (which includes dividend income) were treated as direct taxes on property, and therefore had to be apportioned. Since apportionment of income taxes is impractical, this had the effect of prohibiting a federal tax on income from property. The power to tax real and personal property, or that such was a direct tax, was not denied by the Constitution. [ Chief Justice Fuller's opinion, 158 U.S. 601, 634 [http://www.let.rug.nl/usa/D/1876-1900/reform/pollock.htm] ] Due to the political difficulties of taxing individual wages without taxing income from property, a federal income tax was impractical from the time of the "Pollock" decision until the time of ratification of the Sixteenth Amendment (below).

Ratification of the Sixteenth Amendment

In response, Congress proposed the Sixteenth Amendment (ratified by the requisite number of states in 1913 [United States Government Printing Office, at [http://www.gpoaccess.gov/constitution/html/conamt.html Amendments to the Constitution of the United States of America] ; see generally "United States v. Thomas", 788 F.2d 1250 (7th Cir. 1986), "cert. denied", 107 S.Ct. 187 (1986); "Ficalora v. Commissioner", 751 F.2d 85, 85-1 U.S. Tax Cas. (CCH) paragr. 9103 (2d Cir. 1984); "Sisk v. Commissioner", 791 F.2d 58, 86-1 U.S. Tax Cas. (CCH) paragr. 9433 (6th Cir. 1986); "United States v. Sitka", 845 F.2d 43, 88-1 U.S. Tax Cas. (CCH) paragr. 9308 (2d Cir.), "cert. denied", 488 U.S. 827 (1988); "United States v. Stahl", 792 F.2d 1438, 86-2 U.S. Tax Cas. (CCH) paragr. 9518 (9th Cir. 1986), "cert. denied", 107 S. Ct. 888 (1987); "Brown v. Commissioner", 53 T.C.M. (CCH) 94, T.C. Memo 1987-78, CCH Dec. 43,696(M) (1987); "Lysiak v. Commissioner", 816 F.2d 311, 87-1 U.S. Tax Cas. (CCH) paragr. 9296 (7th Cir. 1987); "Miller v. United States", 868 F.2d 236, 89-1 U.S. Tax Cas. (CCH) paragr. 9184 (7th Cir. 1989); also, see generally Boris I. Bittker, Constitutional Limits on the Taxing Power of the Federal Government, "The Tax Lawyer", Fall 1987, Vol. 41, No. 1, p. 3 (American Bar Ass'n).] ), which states:

The Congress shall have power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States, and without regard to any census or enumeration.

The Supreme Court in "Brushaber v. Union Pacific Railroad," ussc|240|1|1916, indicated that the amendment did not expand the federal government's existing power to tax income (meaning profit or gain from any source) but rather removed the possibility of classifying an income tax as a direct tax on the basis of the source of the income. The Amendment removed the need for the income tax to be apportioned among the states on the basis of population. Income taxes are required, however, to abide by the law of geographical uniformity.

Some tax protesters and others opposed to income taxes cite what they contend is evidence that the Sixteenth Amendment was never "properly ratified," based in large part on materials sold by William J. Benson. In December of 2007, Benson's ""Defense Reliance Package" containing his non-ratification argument which he offered for sale on the internet, was ruled by a federal court to be a "fraud perpetrated by Benson" that had "caused needless confusion and a waste of the customers' and the IRS' time and resources." [Memorandum Opinion, p. 14, Dec. 17, 2007, docket entry 106, "United States v. Benson", case no. 1:04-cv-07403, United States District Court for the Northern District of Illinois, Eastern Division.] The court stated: "Benson has failed to point to evidence that would create a genuinely disputed fact regarding whether the Sixteenth Amendment was properly ratified or whether United States Citizens are legally obligated to pay federal taxes." [Memorandum Opinion, p. 9, Dec. 17, 2007, docket entry 106, "United States v. Benson", case no. 1:04-cv-07403, United States District Court for the Northern District of Illinois, Eastern Division.] "See also Tax protester Sixteenth Amendment arguments."

Modern interpretation of the power to tax incomes

The modern interpretation of the Sixteenth Amendment taxation power can be found in "Commissioner v. Glenshaw Glass Co." ussc|348|426|1955. In that case, a taxpayer had received an award of punitive damages from a competitor for antitrust violations and sought to avoid paying taxes on that award. The Court observed that Congress, in imposing the income tax, had defined gross income, under the Internal Revenue Code of 1939, to include:

gains, profits, and income derived from salaries, wages or compensation for personal service . . . of whatever kind and in whatever form paid, or from professions, vocations, trades, businesses, commerce, or sales, or dealings in property, whether real or personal, growing out of the ownership or use of or interest in such property; also from interest, rent, dividends, securities, or the transaction of any business carried on for gain or profit, or gains or profits and income derived from any source whatever. [348 U.S. at 429]

(Note: this case was under the Tax Code of 1954 and the definition of income found in Title 26 sec. 61. from which our present laws derive.)

The Court held that "this language was used by Congress to exert in this field the full measure of its taxing power", id., and that "the Court has given a liberal construction to this broad phraseology in recognition of the intention of Congress to tax all gains except those specifically exempted." [Id. at 430.]

The Court then enunciated what is now understood by Congress and the Courts to be the definition of taxable income, "instances of undeniable accessions to wealth, clearly realized, and over which the taxpayers have complete dominion." Id. at 431. The defendant in that case suggested that a 1954 rewording of the tax code had limited the income that could be taxed, a position which the Court rejected, stating:

The definition of gross income has been simplified, but no effect upon its present broad scope was intended. Certainly punitive damages cannot reasonably be classified as gifts, nor do they come under any other exemption provision in the Code. We would do violence to the plain meaning of the statute and restrict a clear legislative attempt to bring the taxing power to bear upon all receipts constitutionally taxable were we to say that the payments in question here are not gross income. [Id. at 432-33.]

Tax statutes passed after the ratification of the Sixteenth Amendment in 1913 are sometimes referred to as the "modern" tax statutes. Hundreds of Congressional acts have been passed since 1913, as well as several codifications (i.e., topical reorganizations) of the statutes (see Codification).

"Central Illinois Public Service Co. v. United States", ussc|435|21|1978, confirmed that wages and income are not identical as far as taxes on income are concerned, because income not only "includes" wages, but any "other" gains as well. The Court in that case noted that in enacting taxation legislation, Congress "chose not to return to the inclusive language of the Tariff Act of 1913, but, specifically, 'in the interest of simplicity and ease of administration,' confined the "obligation to withhold" [income taxes] to 'salaries, wages, and other forms of compensation for personal services'" and that "committee reports ... stated consistently that 'wages' meant remuneration 'if paid for services performed by an employee for his employer'". [Id. at 27.]

Other courts have noted this distinction in upholding the taxation not only of wages, but also of personal gain derived from "other" sources, recognizing some limitation to the reach of income taxation. For example, in "Conner v. United States", 303 F. Supp. 1187 (S.D. Tex. 1969), "aff’d in part and rev’d in part", 439 F.2d 974 (5th Cir. 1971), a couple had lost their home to a fire, and had received compensation for their loss from the insurance company, partly in the form of hotel costs reimbursed. The court acknowledged the authority of the IRS to assess taxes on all forms of payment, but did not permit taxation on the compensation provided by the insurance company, because unlike a wage or a sale of goods at a profit, this was not a gain. As the Court noted, "Congress has taxed income, not compensation".

By contrast, other courts have interpreted the Constitution as providing even broader taxation powers for Congress. In Murphy v. IRS, the United States Court of Appeals for the District of Columbia Circuit upheld the Federal income tax imposed on a monetary settlement recovery that the same court had previously indicated was not income, stating: " [a] lthough the 'Congress cannot make a thing income which is not so in fact,' [ . . . ] it can "label" a thing income and tax it, so long as it acts within its constitutional authority, which includes not only the Sixteenth Amendment but also Article I, Sections 8 and 9." [Opinion on rehearing, July 3, 2007, p. 16, "Murphy v. Internal Revenue Service and United States", case no. 05-5139, United States Court of Appeals for the District of Columbia Circuit, 2007-2 U.S. Tax Cas. (CCH) paragr. 50,531 (D.C. Cir. 2007).]

Similarly, in "Penn Mutual Indemnity Co. v. Commissioner", the United States Court of Appeals for the Third Circuit indicated that Congress could properly impose the Federal income tax on a receipt of money, regardless of what that receipt of money is called:

It could well be argued that the tax involved here [an income tax] is an "excise tax" based upon the receipt of money by the taxpayer. It certainly is not a tax on property and it certainly is not a capitation tax; therefore, it need not be apportioned. [ . . . ] Congress has the power to impose taxes generally, and if the particular imposition does not run afoul of any constitutional restrictions then the tax is lawful, call it what you will. ["Penn Mutual Indemnity Co. v. Commissioner", 277 F.2d 16, 60-1 U.S. Tax Cas. (CCH) paragr. 9389 (3d Cir. 1960) (footnotes omitted).]

Tax rates in history

History of top rates

* In 1913 the tax rate was 1% on taxable net income above $3,000 ($4,000 for married couples), less deductions and exemptions. It rose to a rate of 7% on incomes above $500,000.
* During World War I the top rate rose to 77%; after the war, the top rate was scaled down to a low of 25%.
* During the Great Depression and World War II, the top income tax rate rose again. In the Internal Revenue Code of 1939, the top rate was 75%. The top rate reached 94% during the war and remained at 91% until 1964.
* In 1964 the top rate was decreased to 70% (1964 Revenue Act), then to 50% in 1981 (Economic Recovery Tax Act or ERTA).
* The Tax Reform Act of 1986 reduced the top rate to 28%, at the same time raising the bottom rate from 11% to 15% (in fact 15% and 28% became the only two tax brackets).
* During the 1990s the top rate rose again, standing at 39.6% by the end of the decade.
* The top rate was cut to 35% and the bottom rate was cut to 10% by the Economic Growth and Tax Relief Reconciliation Act of 2001 (EGTRRA).

History of progressivity in federal income tax

The federal income tax rates in the United States have varied widely since 1913. For example, in 1954 the Congress imposed a federal income tax on individuals, with the tax imposed in layers of 24 income brackets at tax rates ranging from 20% to 91% (for a chart, see Internal Revenue Code of 1954). Here is a partial history of changes in the U.S. federal income tax rates for individuals (and the income brackets) since 1913: [ [http://www2.census.gov/prod2/statcomp/documents/CT1970p2-01.pdf Historical Statistics of the United States: Colonial Times to 1970 p.1095] ]

The Tax Foundation states that the tax cuts signed by U.S. Presidents Ronald Reagan and George W. Bush, contrary to popular belief, actually made the U.S. tax code more progressive, not less. In 1980, before Reagan's tax cuts, the richest 1% paid 19.05% of all federal income taxes, and by 1988, after Reagan's tax cuts, their share had increased to 27.58%. Likewise, in 2001, before Bush's tax cuts, the richest 1% paid 33.89% of all federal income taxes, and by 2006, after Bush's tax cuts, their share had increased to 39.89%. [ [http://www.taxfoundation.org/news/show/250.html Total Income Tax Shares, 1980-2006] , Summary of Latest Federal Individual Income Tax Data, Table 6, Source: Internal Revenue Service, July 18, 2008]

Federal tax revenue always equals approximately 19.5% of GDP.

Hauser's Law is a theory that states that in the United States, federal tax revenues will always be equal to approximately 19.5% of GDP, regardless of what the top marginal tax rate is. The theory was first suggested in 1993 by Kurt Hauser, a San Francisco investment economist, who wrote at the time, "No matter what the tax rates have been, in postwar America tax revenues have remained at about 19.5% of GDP." In a May 20, 2008 editorial, the Wall St. Journal published a graph showing that even though the top marginal tax rate of federal income tax had varied between a low of 28% to a high of 91% between 1950 and 2007, federal tax revenues had indeed constantly remained at about 19.5% of GDP. [ [http://online.wsj.com/article/SB121124460502305693.html You Can't Soak the Rich] , Wall St. Journal, May 20, 2008.]

ources of U.S. income tax laws

United States income tax law comes from a number of sources. These sources have been divided into three tiers as follows: [Samuel A. Donaldson, Federal Income Taxation of Individuals: Cases, Problems and Materials, 4 (2nd Ed. 2007). ]

* "Tier 1"
** United States Constitution
** Internal Revenue Code (IRC) (legislative authority, written by the United States Congress through legislation)
** Treasury regulations
** Federal court opinions (judicial authority, written by courts as interpretation of legislation)
** Treaties (executive authority, written in conjunction with other countries)

* "Tier 2"
** Agency interpretative regulations (executive authority, written by the Internal Revenue Service (IRS) and Department of the Treasury), including:
*** Final, Temporary and Proposed Regulations promulgated under IRC § 7805;
*** Treasury Notices and Announcements;
** Public Administrative Rulings (IRS Revenue Rulings, which provide informal guidance on specific questions and are binding on all taxpayers)

*"Tier 3"
** Legislative History
** Private Administrative Rulings (private parties may approach the IRS directly and ask for a Private Letter Ruling on a specific issue - these rulings are binding only on the requesting taxpayer).

Where conflicts exist between various sources of tax authority, an authority in Tier 1 outweighs an authority in Tier 2 or 3. Similarly, an authority in Tier 2 outweighs an authority in Tier 3. ["Id."] Where conflicts exist between two authorities in the same tier, the "last-in-time rule" is applied. As the name implies, the "last-in-time rule" states that the authority that was issued later in time is controlling. ["Id."]

Regulations and case law serve to interpret the statutes. Additionally, various sources of law attempt to "do" the same thing. Revenue Rulings, for example, serves as an interpretation of how the statutes apply to a very specific set of facts. Treaties serve in an international realm.

The complexity of the U.S. income tax laws

Even venerable legal scholars like Judge Learned Hand have expressed amazement and frustration with the complexity of the U.S. income tax laws. In the article, "Thomas Walter Swan", 57 Yale Law Journal No. 2, 167, 169 (December 1947), Judge Hand wrote:

In my own case the words of such an act as the Income Tax… merely dance before my eyes in a meaningless procession: cross-reference to cross-reference, exception upon exception — couched in abstract terms that offer [me] no handle to seize hold of [and that] leave in my mind only a confused sense of some vitally important, but successfully concealed, purport, which it is my duty to extract, but which is within my power, if at all, only after the most inordinate expenditure of time. I know that these monsters are the result of fabulous industry and ingenuity, plugging up this hole and casting out that net, against all possible evasion; yet at times I cannot help recalling a saying of William James about certain passages of Hegel: that they were no doubt written with a passion of rationality; but that one cannot help wondering whether to the reader they have any significance save that the words are strung together with syntactical correctness.

Complexity is a separate issue from flatness of rate structures. In the United States, income tax codes are often legislatures' favored policy instrument for encouraging numerous undertakings deemed socially useful — including the buying of life insurance, the funding of employee health care and pensions, the raising of children, home ownership, development of alternative energy sources and increased investment in conventional energy. Special tax rebates granted for any purpose increase complexity, irrespective of the system's flatness or lack thereof.

tate and territorial income taxes

Income tax may also be levied by individual U.S. states and are on top of the federal income tax. In addition, some states allow individual cities to impose an additional income tax. However, some state and local taxes are deductible for federal tax purposes. Through this deduction, the federal government effectively subsidizes a portion of an individual's state income tax. Not all states levy an income tax and U.S. territories such as Puerto Rico and Guam pay no federal income tax.

Arguments against income taxation

A libertarian viewpoint proposes the existence of a natural right to "enjoy all the fruits of one's own labor" (previously protected, some libertarians claim, by the Ninth Amendment). Taxation of income is argued to be an infringement on that right. Under this argument, income taxation offers the federal government a technique to radically diminish the power of the states, because the federal government is then able to distribute funding to states with conditions attached, often giving the states no choice but to submit to federal demands.

Proponents of a consumption tax argue that the income tax system creates perverse incentives by encouraging taxpayers to spend rather than save: a taxpayer is only taxed once on income spent immediately, while any interest earned on saved income is itself taxed. [John Stuart Mill's argument, reported by Marvin A. Chirelstein, "Federal Income Taxation", p. 433 (Foundation Press, 10th Ed., 2005)] To the extent that this is considered unjust, it may be remedied in a variety of ways, "e.g." excluding investment income from taxable income, making investments deductible and therefore only taxing them when gains are realized, or replacing the income tax by other forms of tax, such as a sales tax. [Chirelstein, "loc.cit."] The proposed "Fair Tax Act", a bill before the U.S. Congress, repeals the income tax in favor of a national sales tax with a rebate, and calls for a repeal of the Sixteenth Amendment.

ee also

*Taxation in the United States
*Payroll taxes in the United States
*Sales taxes in the United States
*State income tax
*State tax levels
*Federal tax revenue by state
*Flat Tax: Proposals to alter the federal income tax with a single rate.
*FairTax: Proposal to replace the federal income tax with a national sales tax.
*Taxation of illegal income in the United States
*Internal Revenue Code § 212 - tax deductibility of investment expenses
*Tax preparation
*Tax protester
*Tax resister
*US State NonResident Withholding Tax
*""
*Tax Day

References

External links

* [http://taxalmanac.org TaxAlmanac - Online tax collaboration] A wiki created by tax professionals with detailed information on US IRS Tax Law and the only known free up to date copy of the US Internal Revenue Code.
* [http://www.irs.gov/pub/irs-utl/friv_tax.pdf IRS publication: The Truth About Frivolous Tax Arguments]
* [http://www.treas.gov/education/fact-sheets/taxes/ustax.shtml US Department of Treasury] Official fact sheet on income taxes in the US.