Most individual U.S. states collect a state income tax in addition to federal income tax. In addition, some local governments impose an income tax, often based on state income tax calculations. Forty-three states and many localities in the United States impose an income tax on individuals. Forty-seven states and many localities impose a tax on the income of corporations.
State income tax is imposed at a fixed or graduated rate on the taxable income of individuals, corporations, and certain estates and trusts. The rates vary by state. Taxable income conforms closely to federal taxable income in most states, with limited modifications. The states are prohibited from taxing income from federal bonds or other obligations. Most do not tax Social Security benefits or interest income from obligations of that state. Several states require different useful lives and methods be used by businesses in computing the deduction for depreciation. Many states allow a standard deduction or some form of itemized deductions. States allow a variety of tax credits in computing tax.
Each state administers its own tax system. Many states also administer the tax return and collection process for localities within the state that impose income tax.
State income tax is allowed as a deduction in computing federal income tax, subject to limitations for individuals.
characterization of business entities as either corporations, partnerships, or disregarded.
Gross income generally includes all income earned or received from whatever source, with exceptions. The states are prohibited from taxing income from federal bonds or other obligations. Most states also exempt income from bonds issued by that state or localities within the state, as well as some portion or all of Social Security benefits. Many states provide tax exemption for certain other types of income, which varies widely by state. The states imposing an income tax uniformly allow reduction of gross income for cost of goods sold, though the computation of this amount may be subject to some modifications.
Most states provide for modification of both business and non-business deductions. All states taxing business income allow deduction for most business expenses. Many require that depreciation deductions be computed in manners different from at least some of those permitted for federal income tax purposes. For example, many states do not allow the additional first year depreciation deduction.
Most states tax capital gain and dividend income in the same manner as other investment income. In this respect, individuals and corporations not resident in the state generally are not required to pay any income tax to that state with respect to such income.
Some states have alternative measures of tax. These include analogs to the federal Alternative Minimum Tax in 14 states, as well as measures for corporations not based on income, such as capital stock taxes imposed by many states.
Income tax is self assessed, and individual and corporate taxpayers in all states imposing an income tax must file tax returns in each year their income exceeds certain amounts determined by each state. Returns are also required by partnerships doing business in the state. Many states require that a copy of the federal income tax return be attached to at least some types of state income tax returns. The time for filing returns varies by state and type of return, but for individuals in many states is the same (typically April 15) as the federal deadline .
Every state, including those with no income tax, has a state taxing authority with power to examine (audit) and adjust returns filed with it. Most tax authorities have appeals procedures for audits, and all states permit taxpayers to go to court in disputes with the tax authorities. Procedures and deadlines vary widely by state. All states have a statute of limitations prohibiting the state from adjusting taxes beyond a certain period following filing returns.
All states have tax collection mechanisms. States with an income tax require employers to withhold state income tax on wages earned within the state. Some states have other withholding mechanisms, particularly with respect to partnerships. Most states require taxpayers to make quarterly payments of tax not expected to be satisfied by withholding tax.
All states impose penalties for failing to file required tax returns and/or pay tax when due. In addition, all states impose interest charges on late payments of tax, and generally also on additional taxes due upon adjustment by the taxing authority.
Forty-three states impose a tax on the income of individuals, sometimes referred to as personal income tax. State income tax rates vary widely from state to state. South Carolina has the lowest marginal tax rate at 0% for the first $2,850 of personal income, while California has the highest marginal rate of 13.3% for the portion of incomes over $1,000,000. Some states impose the tax on federal taxable income with minimal modifications, while others tax a measure bearing little resemblance to federal taxable income.
The states imposing an income tax on individuals tax all taxable income (as defined in the state) of residents. Such residents are allowed a credit for taxes paid to other states. Most states tax income of nonresidents earned within the state. Such income includes wages for services within the state as well as income from a business with operations in the state. Where income is from multiple sources, formulary apportionment may be required for nonresidents. Generally, wages are apportioned based on the ratio days worked in the state to total days worked.
All states that impose an individual income tax allow most business deductions. However, many states impose different limits on certain deductions, especially depreciation of business assets. Most of the states allow non-business deductions in a manner similar to federal rules. Few allow a deduction for state income taxes, though some states allow a deduction for local income taxes. Eight of the states allow a full or partial deduction for federal income tax.
In addition, some states allow cities and/or counties to impose income taxes. For example, most Ohio cities and towns impose an income tax on individuals and corporations. By contrast, in New York, only New York City and Yonkers impose a municipal income tax.
States with no individual income tax
States with no state individual income tax are in red, states taxing only dividend and interest income are in yellow.
Nine U.S. states do not level a broad-based individual income tax. Some of these do tax certain forms of personal income:
Alaska – no individual tax but has a state corporate income tax. Like New Hampshire, Alaska has no state sales tax, but unlike New Hampshire, Alaska allows local governments to collect their own sales taxes. Alaska has an annual Permanent Fund Dividend, derived from oil revenues, for all citizens living in Alaska after one calendar year, except for some convicted of criminal offenses.
Florida – no individual income tax but has a 5.5% corporate income tax. The state once had a tax on "intangible personal property" held on the first day of the year (stocks, bonds, mutual funds, money market funds, etc.), but it was abolished at the start of 2007.
Nevada – has no individual or corporate income tax. Nevada gets most of its revenue from sales taxes and the gambling and mining industries.
New Hampshire – has an Interest and Dividends Tax of 5%, and a Business Profits Tax of 8.5%. A Gambling Winnings Tax of 10% went into effect July 1, 2009 and was repealed May 11, 2011. New Hampshire has no sales tax.
South Dakota – no individual income tax but has a state corporate income tax on financial institutions.
Tennessee has a 6% tax on income received from stocks and bonds not taxed ad valorem. In 1932, the Tennessee Supreme Court struck down a broad-based individual income tax that had passed the General Assembly, in the case of Evans v. McCabe. However, a number of Attorneys General have recently opined that, if properly worded, a state income tax would be found constitutional by today's court, due to a 1971 constitutional amendment.
Texas – no individual income tax but imposes a franchise tax on corporations. In May 2007, the legislature replaced the franchise tax with a gross margins tax on businesses (sole proprietorships and some partnerships were automatically exempt; corporations with receipts below a certain level were also exempt as were corporations whose tax liability was also below a specified amount), which was amended in 2009 to increase the exemption level. The Texas Constitution places severe restrictions on passage of an individual income tax and use of its proceeds.
Washington – no individual tax but has a business and occupation tax (B&O) on gross receipts, applied to "almost all businesses located or doing business in Washington." It varies from 0.138% to 1.9% depending on the type of industry.
Wyoming has no individual or corporate income taxes.
Most states impose a tax on income of corporations having sufficient connection ("nexus") with the state. Such taxes apply to U.S. and foreign corporations, and are not subject to tax treaties. Such tax is generally based on business income of the corporation apportioned to the state plus nonbusiness income only of resident corporations. Most state corporate income taxes are imposed at a flat rate and have a minimum amount of tax. Business taxable income in most states is defined, at least in part, by reference to federal taxable income.
According to www.taxfoundation.org these states have no state corporate income tax as of Feb 1, 2010: Nevada, Washington, Wyoming, Texas, and South Dakota. However, Texas has a franchise tax based on "taxable margin", generally defined as sales less either cost of goods sold less compensation, with complete exemption (no tax owed) for less than $1MM in annual earnings and gradually increasing to a maximum tax of 1% based on net revenue, where net revenue can be calculated in the most advantageous of four different ways.
There must be a "substantial nexus" (connection) between the taxpayer's activities and the state,
The tax must not discriminate against interstate commerce,
The tax must be fairly apportioned, and
There must be a fair relationship to services provided.
Substantial nexus (referred to generally as simply "nexus") is a general U.S. Constitutional requirement that is subject to interpretation, generally by the state's comptroller or tax office, and often in administrative "letter rulings".
In Quill Corp. v. North Dakota the Supreme Court of the United States confirmed the holding of National Bellas Hess v. Illinois  that a corporation or other tax entity must maintain a physical presence in the state (such as physical property, employees, officers) for the state to be able to require it to collect sales or use tax. The Supreme Court's physical presence requirement in Quill is likely limited to sales and use tax nexus, but the Court specifically stated that it was silent with respect to all other types of taxes  "Whether "Quill" applies to corporate income and similar taxes is a point of contention between states and taxpayers. The "substantial nexus" requirement of "Complete Auto", supra, has been applied to corporate income tax by numerous state supreme courts.
The courts have held that the requirement for fair apportionment may be met by apportioning between jurisdictions all business income of a corporation based on a formula using the particular corporation's details. Many states use a three factor formula, averaging the ratios of property, payroll, and sales within the state to that overall. Some states weight the formula. Some states use a single factor formula based on sales.
Some states tax resident corporations on nonbusiness income regardless of apportionment. Generally, a resident corporation is one incorporated in that state. The definition of nonbusiness income varies but generally includes investment income of business corporations, including dividends.
Consolidated or unitary filings
Some states require and some states permit parent/subsidiary controlled groups of corporations to file returns on a consolidated or combined basis. California and Illinois require that all U.S. members of a "unitary" group must file a combined return.
State corporate income tax returns vary highly in complexity from two pages to more than 20 pages. States often require that a copy of the federal income tax return be attached to the state return. Corporate income tax return due dates may differ from individual tax return due dates. Most states grant extensions of time to file corporate tax returns.
Some of the English colonies in North America taxed property (mostly farmland at that time) according to its assessed produce, rather than, as now, according to assessed resale value. Some of these colonies also taxed "faculties" of making income in ways other than farming, assessed by the same people who assessed property. These taxes taken together can be considered a sort of income tax. The records of no colony covered by Rabushka (the colonies that became part of the United States) separated the property and faculty components, and most records indicate amounts levied rather than collected, so much is unknown about the effectiveness of these taxes, up to and including whether the faculty part was actually collected at all.
Colonies with laws taxing both property and faculties
Rabushka makes it clear that Massachusetts and Connecticut actually levied these taxes regularly, while for the other colonies such levies happened much less often; South Carolina levied no direct taxes from 1704 through 1713, for example. Becker, however, sees faculty taxes as routine parts of several colonies' finances, including Pennsylvania.
During and after the American Revolution, although property taxes were evolving toward the modern resale-value model, several states continued to collect faculty taxes.
States with faculty taxes
Massachusetts until 1916 (when it was replaced by a quasi-modern classified individual income tax);
Connecticut until 1819;
South Carolina, where the tax edged closer to a modern income tax, until 1868;
and Pennsylvania from 1782 to 1840 (when it was replaced by an individual income tax; Becker, as noted above, would date this tax earlier).
Between the enactment of the Constitution and 1840, no new general taxes on income appeared. In 1796, Delaware abolished its faculty tax, and in 1819 Connecticut followed suit. On the other hand, in 1835, Pennsylvania instituted a tax on bank dividends, paid by withholding, which by about 1900 produced half its total revenue.
Several states, mostly in the South, instituted taxes related to income in the 1840s; some of these claimed to tax total income, while others explicitly taxed only specific categories, these latter sometimes called classified income taxes. These taxes may have been spurred by the ideals of Jacksonian democracy, or by fiscal difficulties resulting from the Panic of 1837. None of these taxes produced much revenue, partly because they were collected by local elected officials. A list:
Early state income taxes
Pennsylvania from 1840 to 1871;
Maryland from 1841 to 1850;
Alabama from 1843 to 1884;
Virginia from 1843 to 1926 (when it was replaced by a modern individual income tax);
Florida from 1845 to 1855;
and North Carolina from 1849 to 1921 (when it was replaced by a modern individual income tax).
The 1850s brought another few income tax abolitions: Maryland and Vermont in 1850, and Florida in 1855.
During the American Civil War and Reconstruction Era, when both the United States of America (1861-1871) and the Confederate States of America (1863-1865) instituted income taxes, so did several states.
As with the national taxes, these were made in various ways to produce substantial revenue, for the first time in the history of American income taxation. On the other hand, as soon as the war ended, a wave of abolitions began: Missouri in 1865, Georgia in 1866, South Carolina in 1868, Pennsylvania and Texas in 1871, and Kentucky in 1872.
The rest of the century balanced new taxes with abolitions: Delaware levied a tax on several classes of income in 1869, then abolished it in 1871; Tennessee instituted a tax on dividends and bond interest in 1883, but Kinsman reports that by 1903 it had produced zero actual revenue; Alabama abolished its income tax in 1884; South Carolina instituted a new one in 1897 (eventually abolished in 1918); and Louisiana abolished its income tax in 1899.
Following the 1895 Supreme Court decision in Pollock v. Farmers' Loan & Trust Co. which effectively ended a federal income tax, some more states instituted their own along the lines established in the 19th century:
Old-fashioned state income taxes
Oklahoma 1908 to 1915;
Mississippi 1912 to 1924;
Missouri, individual and corporate, from 1917.
However, other states, some perhaps spurred by Populism, some certainly by Progressivism, instituted taxes incorporating various measures long used in Europe, but considerably less common in America, such as withholding, corporate income taxation (as against earlier taxes on corporate capital), and especially the defining feature of a "modern" income tax, central administration by bureaucrats rather than local elected officials. The twin revenue-raising successes of Wisconsin's 1911 and the United States' 1914 income taxes prompted imitation. Note that writers on the subject sometimes distinguish between corporate "net income" taxes, which are straightforward corporate income taxes, and corporate "franchise" taxes, which are taxes levied on corporations for doing business in a state, sometimes based on net income. Many states' constitutions were interpreted as barring direct income taxation, and franchise taxes were seen as legal ways to evade these bars. The term "franchise tax" has nothing to do with the voting franchise, and franchise taxes only apply to individuals insofar as they do business. Note that some states actually levy both corporate net income taxes and corporate franchise taxes based on net income. For the following list see  and.
Progressive Era state income taxes
The Territory of Hawaii, then Hawaii as a state, individual and corporate from 1901 (this is sometimes claimed as the oldest state income tax; it is certainly the oldest state corporate income tax);
Wisconsin, individual and corporate from 1911 (generally considered the first modern state income tax, built on a law largely written by Delos Kinsman, whose 1903 book on the subject is cited above; its major distinction as against older laws, including Hawaii's, is that state bureaucrats rather than local assessors collected it);
Connecticut, franchise, from 1915;
Oklahoma, modernisation of existing individual tax, from 1915;
Massachusetts, individual, from 1916;
Virginia, corporate, from 1916;
Delaware, individual, from 1917;
Montana, franchise, from 1917;
New York, franchise, from 1917;
Note abolition of South Carolina's non-modern individual income tax in 1918;
New Mexico, individual and corporate, 1919, apparently abolished soon thereafter;
New York, individual, from 1919;
North Dakota, individual and corporate, from 1919;
Massachusetts, corporate (franchise), from 1919 or 1920;
Mississippi's income tax was held to apply to corporations in 1921;
North Carolina, modernisation of existing individual and institution of corporate taxes, from 1921;
South Carolina, individual and corporate, from 1921 or 1922;
New Hampshire, "intangibles" (restricted to interest and dividends), from 1923;
Oregon, individual and corporate, 1923 (repealed 1924);
Tennessee, corporate, from 1923;
Mississippi, modernisation of existing corporate and individual taxes, from 1924;
Virginia, modernisation of existing corporate and individual taxes, from 1926.
This period coincided with the United States' acquisition of colonies, or dependencies: the Philippines, Puerto Rico, and Guam from Spain in the Spanish–American War, 1898–99; American Samoa by agreements with local leaders, 1899-1904; the Panama Canal Zone by agreement from Panama in 1904; and the U.S. Virgin Islands purchased from Denmark in 1917. (Arguably, Alaska, purchased from Russia in 1867, and Hawaii, annexed in 1900, were also dependencies, but both were by 1903 "incorporated" in the U.S., which these others never have been.) The Panama Canal Zone was essentially a company town, but the others all began levying income taxes under American rule. (Puerto Rico already had an income tax much like a faculty tax, which remained in effect for a short time after 1898.)
Early territorial income taxes
The Philippines and Puerto Rico, from 1913, by the same law that instituted the federal income tax; this law is ancestral to the modern independent Philippines' income tax as well; and
A third of the current state individual income taxes, and still more of the current state corporate income taxes, were instituted during the decade after the Great Depression started:
Depression state income taxes
Arkansas, individual and corporate, from 1929;
California, franchise, from 1929;
Georgia, individual and corporate, from 1929;
Oregon, individual, franchise, and intangibles, from 1929, but the individual tax didn't take effect until 1930 and was restricted to use for property tax relief, and the intangibles tax was held unconstitutional in 1930;
Tennessee, intangibles, from 1929;
Idaho, individual and corporate, from 1931;
Ohio, intangibles, from 1931, apparently abolished soon thereafter;
Oklahoma, corporate, from 1931;
Oregon, intangibles, 1931 to 1939;
Utah, individual and franchise, from 1931;
Vermont, individual and corporate, from 1931;
Illinois, individual and corporate, 1932, soon declared unconstitutional;
Washington, individual and corporate, 1932, declared unconstitutional 1933;
Alabama, individual and corporate, from 1933;
Arizona, individual and corporate, from 1933;
Kansas, individual and corporate, from 1933;
Minnesota, individual, corporate, and franchise, from 1933;
Montana, individual and corporate, from 1933;
New Mexico, individual and corporate, from 1933;
Iowa, individual and franchise, from 1934;
Louisiana, individual and corporate, from 1934;
California, individual and corporate, from 1935;
Pennsylvania, franchise, from 1935;
South Dakota, individual and corporate, 1935 to 1943;
The U.S. Virgin Islands income tax in 1935 became the first "mirror" tax, for which see below;
Washington, individual and corporate, 1935, held unconstitutional in separate decisions the same year;
West Virginia, individual, 1935 to 1942;
Kentucky, individual and corporate, from 1936;
Colorado, individual and corporate, from 1937;
Maryland, individual and corporate, from 1937;
District of Columbia, individual and either corporate or franchise, from 1939.
A "mirror" tax is a tax in a U.S. dependency in which the dependency adopts wholesale the U.S. federal income tax code, revising it by substituting the dependency's name for "United States" everywhere, and vice versa. The effect is that residents pay the equivalent of the federal income tax to the dependency, rather than to the U.S. government. Although mirroring formally came to an end with the Tax Reform Act of 1986, it remains the law as seen by the U.S. for Guam and the Northern Mariana Islands because conditions to its termination have not yet been met. In any event, the other mirror tax dependencies (the U.S. Virgin Islands and American Samoa) are free to continue mirroring if, and as much as, they wish.
The U.S. acquired one more dependency from Japan in World War II: the Trust Territory of the Pacific Islands.
Two states, South Dakota and West Virginia, abolished Depression-era income taxes in 1942 and 1943, but these were nearly the last abolitions. For about twenty years after World War II, new state income taxes appeared at a somewhat slower pace, and most were corporate net income or corporate franchise taxes:
As early as 1957 General Motors protested a proposed corporate income tax in Michigan with threats of moving manufacturing out of the state. However, Michigan led off the most recent group of new income taxes:
Great Society state income taxes
Michigan, individual and corporate (this replacing a value-added tax), from 1967;
Nebraska, individual and corporate, from 1967;
Maryland, individual (added county withholding tax and non resident tax. Believes led to state being mainly a commuter state for work) 1967,Present
West Virginia, corporate, from 1967;
Connecticut, intangibles (but taxing capital gains and not interest), from 1969;
Illinois, individual and corporate, from 1969;
Maine, individual and corporate, from 1969;
New Hampshire, corporate, from 1970;
Florida, franchise, from 1971;
Ohio, individual and corporate, from 1971;
Pennsylvania, individual, from 1971;
Rhode Island, individual, from 1971;
The Trust Territory of the Pacific Islands, individual and corporate, from 1971.
In the early 1970s, Pennsylvania and Ohio competed for businesses with Ohio wooing industries with a reduced corporate income tax but Pennsylvania warning that Ohio had higher municipal taxes that included taxes on inventories, machinery and equipment.
Michigan abolished its corporate income tax in 1975, replacing it with another value-added tax;
New Jersey instituted an individual income tax in 1976;
The Northern Mariana Islands negotiated with the U.S. in 1975 a mirror tax which was to go into effect in 1979, but in 1979 enacted a law rebating that tax partially or entirely each year and levying a simpler income tax;
Alaska abolished its individual income tax retroactive to 1979 in 1980.
(Also during this time the U.S. began returning the Panama Canal Zone to Panama in 1979, and self-government, eventually to lead to independence, began between 1979 and 1981 in all parts of the Trust Territory of the Pacific Islands except for the Northern Mariana Islands. The resulting countries - the Marshall Islands, the Federated States of Micronesia, and Palau - all levy income taxes today.)
The only subsequent individual income tax instituted to date is Connecticut's, from 1991, replacing the earlier intangibles tax. The median family income in many of the state's suburbs was nearly twice that of families living in urban areas. Governor Lowell Weicker's administration imposed a personal income tax to address the inequities of the sales tax system, and implemented a program to modify state funding formulas so that urban communities received a larger share.
Numerous states with income taxes have considered measures to abolish those taxes since the Late-2000s recession began, and several states without income taxes have considered measures to institute them, but only one such proposal has been enacted: Michigan replaced its more recent value-added tax with a new corporate income tax in 2009.
^For example, Colorado adjusts federal taxable income only for state income tax, interest on federal obligations, a limited subtraction for pensions, payments to the state college tuition fund, charitable contributions for those claiming the standard deduction, and a few other items of limited applicability. See 2010 Colorado individual income tax booklet. By contrast, Tennessee taxes individuals only on interest and dividend income; see 2010 Tennessee individual income tax return kit.
^"Publications". Ohio Department of Taxation. Retrieved 5 June 2013. "Since 1975, the department has published a Brief Summary of Major State & Local Taxes in Ohio, designed to be a quick overview of all of the state's significant state and local taxes."
^Massachusetts taxes certain types of gains at a flat 12%; a subset of those allow a 50% deduction, producing an effective rate of 6%. These tiers are still considered flat, since they are based on the type of income, and not the amount. See Individual Income Tax Provisions in the States.
^504 U.S. 298, 314 ("Although we have not, in our review of other types of taxes, articulated the same physical-presence requirement that Bellas Hess established for sales and use taxes, that silence does not imply repudiation of the Bellas Hess rule.").
^See, e.g., "Tax Commissioner of the State of West Virginia v. MBNA America Bank, 220 W. Va. 163, 640 S.E.2d 226, 231 (2006), cert. denied, 551 U.S. 1141.
^See, generally, "MBNA", supra, and "Geoffrey, Inc. v. South Carolina Tax Commission, 313 S.C. 15, 437 S.E.2d 13
^See, e.g., the discussion in Hellerstein, Hellerstein & Youngman, State and Local Taxation, Chapter 8 section C. ISBN 0-314-15376-4.
^For a compilation of formulas, see State Tax Handbook published annually by CCH.
^Seligman, Edwin R.A. (1914). The Income Tax: A Study of the History, Theory, and Practice of Income Taxation at Home and Abroad. Second edition, revised and enlarged with a new chapter. New York: The Macmillan Company. Underlies most of the history section through 1911, although several examples of sloppiness are recorded below, but for the faculty taxes and Seligman's evaluation of them as income taxes, see Part II Chapter I, pp. 367-387.
^Rabushka, Alvin (2008). Taxation in Colonial America. Princeton: Princeton University Press. ISBN 978-0-691-13345-4
^Becker, Robert A. (1980). Revolution, Reform, and the Politics of American Taxation, 1763-1783. Baton Rouge and London: Louisiana State University Press. ISBN 0-8071-0654-2
^Kinsman, Delos Oscar (1900). The Income Tax in the Commonwealths of the United States. Ithaca: Publications of the American Economic Association, Third Series, Vol. IV, No. 4. A source for the history section through 1900 in general, but specifically for the Virginia faculty tax see pp. 13-14. The tax from 1786 to 1790 referred to by Seligman, p. 380, is simply a tax on court clerks also mentioned by Kinsman, and as a tax on a single occupation is not listed here. Later writers have typically followed Seligman, but the tax referred to by Kinsman is in fact reported in the sources he cites, Hennings' Statutes at Large, volumes IX pp. 350, 353-354, and 548, and amended out of existence where he says, Hennings volume XI p. 112. For the 1786-1790 tax see Hennings volume XII pp. 283-284 and repeal in volume XIII p. 114
^Comstock, Alzada (1921). State Taxation of Personal Incomes. Volume CI, Number 1, or Whole Number 229, of Studies in History, Economics and Public Law edited by the Faculty of Political Science of Columbia University. New York: Columbia University. On the Panic of 1837 see p. 14.
^State Taxation of Interstate Commerce. Report of the Special Subcommittee on State Taxation of Interstate Commerce of the Committee on the Judiciary, House of Representatives. Pursuant to Public Law 86-272, as Amended. 88th Congress, 2d Session, House Report No. 1480, volume 1. (Usually abbreviated House Report 88-1480.) Often referred to as the "Willis committee report" after chair Edwin E. Willis. See p. 99.
^Foster, Roger (1915). A Treatise on the Federal Income Tax under the Act of 1913. Second edition. Rochester, N.Y.: The Lawyers Co-operative Publishing Co. Pp. 889-894.
^Legislative Interim Tax Study Committee (1958). Development of State Income Taxes in the United States and Oregon. Salem, OR. Pp. 21-22.
^Rowe, L[eo] S. (1904). The United States and Porto Rico. New York: Longmans, Green, and Co., but seen as New York: Arno Press, 1975, ISBN 0-405-06235-4. Pp. 188-190.
^Tantuico, Sr., Francisco, and Francisco Tantuico, Jr. (1961). Rules and Rulings on the Philippine Income Tax. Tacloban: The Leyte Publishing Corp. Pp. 3-5.
^Clark, Victor S., et alii (1930). Porto Rico and Its Problems. Washington: The Brookings Institution. P. 200.
^Chyatte, Scott G. (1988). "Taxation through the Looking Glass: The Mirror Theory and the Income Tax System of the U.S. Virgin Islands before and after the Tax Reform Act of 1986". Pp. 170-205 of Volume 6, Issue 1 of Berkeley Journal of International Law. Pp. 173-176.
^Blakey, Roy G., and Violet Johnson (1942). State Income Taxes. New York: Commerce Clearing House. List pp.3-4.
^ abPenniman, Clara, and Walter W. Heller (1959). State Income Tax Administration. Chicago: Public Administration Service. Chart pp. 7-8.
^ abcdPenniman, Clara (1980). State Income Taxation. Baltimore and London: The Johns Hopkins University Press. ISBN 0-8018-2290-4. Chart pp. 2-3.
^Legislative Interim Tax Study Committee, pp. 24-28.
^ abWashington State Research Council (1964). A State Income Tax: pro & con. Pp. 6-7.
^Joint Committee on Taxation (2012). Federal Tax Law and Issues Related to the United States Territories. JCX-41-12. Pp. 8, 20, and 22.