UPDATE: Researching International Tax Law

By Christopher C. Dykes

Chris Dykes is currently the Head of Public Services at the University of Houston Law Center’s O’Quinn Law Library. He received his Juris-Doctor from the University of Baltimore School of Law and LL.M. in Taxation from Villanova University School of Law. He also holds a B.A. in Political Science and M.S. in Information Sciences from The University of Tennessee. [1]

Published April 2019

(Previously updated in January/February 2015)

See the Archive Version!

1. Introduction

This research guide, based on International Tax Law: A Legal Research Guide (Buffalo: Hein, 2011) by Christopher C. Dykes, is designed to provide a starting point for those interested in international tax research. This guide will focus on international tax law from the global perspective but will also list information and sources for those interested in U.S. international taxation. This research guide will also discuss model income tax conventions, tax treaties, customary international law, and general principles of law. Secondary sources such as selected treatises, practice guides, and journals as well as online sources and research guides will also be covered.

2. Primary Sources

2.1. Vienna Convention on the Law of Treaties[2]

This convention was adopted May 22, 1969 and entered into force on January 27, 1980.[3] It is important because it provides the standards for all treaties, including tax treaties. Today, it has been ratified by 96 nations and there are 45 signatories, but the United States (although a signatory) is among the nations that failed to ratify this convention.[4] Many federal and state appellate courts consider the provisions related to treaty interpretation to be binding despite the fact that the U.S. Senate has never ratified the Vienna Convention.[5]

2.2. Model Tax Conventions

These provide a starting point for tax treaty negotiations between nations. There are three major model conventions that one needs to be familiar with: Organisation for Economic Cooperation and Development (OECD) Model Tax Convention;[6] United States Model Tax Convention;[7] United Nations Model Tax Convention.[8] These three models are not binding but are designed to make tax treaty negotiations easier and to avoid any complications for nations whose laws require ratification.

OECD Model Tax Convention on Income and on Capital (2014 full version, 2017 update, condensed version): The OECD began in 1961 replacing the Organisation for European Economic Co-operation (OECC) created in 1948.[9] The organization today includes 33 nations (mostly developed European nations and the United States). This convention contains commentaries along with reservations from member nations and opposing positions taken from nonmember nations. The OECD model provides the basis for tax treaty negotiations for most developed nations, who either use the model convention as their starting point or adapt most or all of the provisions for their own model tax convention. The OECD recently updated the model tax convention in November 2017, with the condensed version of the latest update now available.[10]

U.S. Model Income Tax Convention (U.S. Model Income Technical Explanation): The U.S Income Tax Convention provides the starting point for the United States in negotiating tax treaties and was originally published in 1981, with revisions made in 1996,2006, and 2016. It contains accompanying technical explanations and is used to ensure that any issues that could potentially complicate the ratification process in the Senate are disposed of during bilateral negotiations. The U.S. model is similar to the OECD model in most respects but differs regarding anti-discrimination provisions related to foreign taxpayers and it also targets the use of tax havens more aggressively.[11]

U.N. Model Double Taxation Convention between Developed and Developing Countries: The United Nations model published in 1980 was designed to assist developing nations with respect to tax treaty negotiations.[12] The U.N. model is similar to the OECD Model and contains some of the same provisions but there are some notable differences such as provisions with blank percentages facilitating greater flexibility in tax treaty negotiations and more of a focus on source based taxation as opposed to residence based taxation.[13] The U.N. Model is substantially different from the U.S. Model because of less rigorous nondiscrimination policies as well as less emphasis on tax fraud and fiscal evasion.

Locating Model Tax Treaties: The model tax conventions can be easily located online via the free internet as well as from the following sources:

2.3. Tax Treaties

Tax treaties are the most authoritative source of international tax law, but that authority is contingent upon how an individual nation views the terms of the treaty in relation to its domestic laws.[14] Some countries view the treaties as automatically binding whereas other countries require special legislative procedures beyond simple ratification before the treaty’s provisions effectively become law. The United States in particular views tax treaties as “the supreme law of the land.”[15] However if there is a conflicting statute such authority depends on whether the treaty was passed later than that statute. [16] Treaties that are passed later in time are more authoritative than those entered into beforehand. [17] Self-executing treaties (those with provisions that stipulate enforcement) have more force in most jurisdictions than non-self-executing treaties.

2.3.1. Purpose of Tax Treaties

Tax treaties exist for the most part to avoid double taxation and prevent tax fraud or fiscal evasion. [18] Double taxation takes place when the taxpayer is taxed by the foreign nation of residence and the home country at the same time. For example, if a U.S. citizen were living abroad in Argentina, that person would not only be subject to taxation in that country but also the United States, regardless of residence. Double taxation is problematic because it can stifle commerce, discourage international trade, and can be particularly devastating to nations whose economies rely heavily on tourism. While double taxation can be crippling to all nations, tax evasion is a greater concern for developed nations than it is for developing nations because they are more likely to lose revenue. The expatriation of U.S. citizens to nations known as “tax havens” that boast little or no tax burden has been a problem in recent years. [19] While Congress has created restrictions designed to discourage this tactic through the enactment of the “Heroes Earnings Assistance and Relief Tax Act of 2008,”[20] there are other maneuvers used to hide assets offshore that will continue to be a major issue in tax treaty negotiations. Tax treaties may also deal with other issues such as nondiscrimination against foreign nationals and the reduction of withholding rates. [21]

There are times when nations cannot agree upon a comprehensive tax treaty and as such will often enter into treaties or agreements that focus on one particular issue. These agreements often include those that protect social security payments from double taxation along with those that focus on tax exemptions and credits for transportation costs, sharing information between nations regarding a particular taxpayer, and double taxation and fraud as it relates to taxes on gifts, estates, and inheritances. The United States has agreements with a number of nations where negotiations for a comprehensive tax treaty have failed. These agreements are viewed as authoritative as ratified treaties from an international standpoint, and domestically, the Supreme Court has upheld the President’s authority to enter into such agreements. [22]

2.3.2. Locating Tax Treaties

Locating U.S. Tax treaties is manageable because of the enormous number of commercial and noncommercial sources available that contain these treaties. Although there are noncommercial sources, commercial services are still important because of the analysis that they provide. Researching non-U.S. tax treaties is extremely difficult unless one has access to a database with the full text of tax treaties because fewer academic law libraries continue to subscribe to the print materials that contain them. The language barrier can also pose problems for those attempting to locate non-U.S. tax treaties from non-commercial sources, making databases with the English translation essential. Treaties Where the United States is a Party

Official Sources:

Commercial Services:

Treaty Guides and Indexes: Treaties Where the United States is Not a Party

2.4. Customary International Law

For those matters not covered by tax treaties, customary international law can help by looking at the “relatively uniform and consistent state practice regarding a particular matter”[23] to determine whether such action was taken based on the obligation or belief that it was legal based on international law.[24] Customary international law will review past actions taken by nations with respect to tax related issues and evidence of such can be found through sources of state practice, digests, and yearbooks.

Sources of State Practice


2.5. General Principles of Law

For matters that cannot be determined by treaties or customary international law, general principles of law can provide guidance to attorneys who are handling issues with little or no legal precedence. These are basic legal concepts that are imperative to all nations and involve matters not readily dealt with by treaties.[26] The authority of general principles of law has been given credibility by the Statute of the International Court of Justice requiring the court to consider, after consulting treaties and customary international law, “the general principles of law recognized by civilized nations” in determining the outcome of cases.[27] General principles of law can be established by looking at case law and scholarly works.[28]

The following is a list of sources that can used to ascertain general principles of law:

3. Secondary Sources

3.1. Treatises/Practice Guides

There are numerous secondary sources that focus on international tax law and these are important because they provide analysis that is fundamental for those who practice or research in this area. Keep in mind that the vast majority of materials focus on international taxation from a U.S. practitioner point of view while fewer sources view international taxation from a global perspective.

U.S. Perspective:

Global Perspective:

3.2. News/Current Awareness

3.3. Selected Journals/Periodicals

3.4. Dictionaries

3.5. Online Research

Online research is essential for international tax research particularly for those who need to access tax treaties and model tax conventions. There are a number of free databases provided by the U.S. government as well as foreign and international agencies but access to subscription databases are imperative for those who need to locate non-U.S. tax treaties.

U.S. Government Agency Websites

Foreign and International Agency Websites

Subscription Databases

4. Research Guides

There are a number of research guides compiled by academic law libraries on the subject of international taxation:

5. Sources Consulted for this Article

[1] Special thanks to the following for their assistance and support: Amanda Watson, Director and Assistant Professor of Law at the University of Houston Law Center, O’Quinn Law Library; Emily Lawson , Associate Director of the University of Houston Law Center, O’Quinn Law Library; and Dan Baker, Reference Librarian at the Capital University Law Library, O’Quinn Law Library.

[2] Vienna Convention on the Law of Treaties, May 23, 1969, 1155 U.N.T.S. 331

[3]1 Roy Rohatgi, Basic International Taxation, §2.2.1, at 27 (2d ed. 2005).

[4] Id.

[5] See Evan J. Criddle, The Vienna Convention on the Law of Treaties in U.S. Treaty Interpretation, 44 Va. J. Int’l, L., 431, 433-434 (2004).

[6] Model Convention with Respect to Taxes on Income and on Capital, as of July 15, 2014, reprinted in OECD Committee on Fiscal Affairs, Model Tax Convention on Income and on Capital—Condensed Version (2014).

[7] United States Model Income Tax Convention of February 17, 2016, hereinafter U.S. Model Income

[8] U.N. Dep’t of Econ. & Soc. Affairs, United Nations Model Double Taxation Convention between Developed and Developing Countries, U.N. Doc. ST/ESA/PAD/SER.E/21, U.N. Sales No. E.01.XVI.2 (2001) hereinafter U.N. Model Tax Convention.

[9] See Hugh J. Ault, Reflections on the Role of the OECD in Developing International Tax Norms, 34 Brook. J. Int’L. L. 757, 758 (2009).

[10] OECD

[11] See U.S. Model Income Tax Convention, art. 24; Joseph Isenbergh, International Taxation 224-225 (3rd ed. 2010).

[12] See U.N. Model Tax Convention, supra note 8, Introduction 2, at vii, 10, at x-xi.

[13] See Rohatgi, supra Note 3, §3.2.1, at 104.

[14] See Mark W. Janis, An Introduction to International Law 100-105(5th ed. 2008).

[15] U.S. Const. art. VI, cl. 2.

[16] See 1 Ronald D. Rotunda & John E. Nowak, Treatise on Constitutional Law-Substance & Procedure 6.7(a) (5th ed. 2017).

[17] Id.

[18] International Tax Law 164-166 (Andrea Amatucci ed., 2012).

[19] See Boris Bittker & Lawrence Loken, Federal Taxation on Income, Estates, and Gifts 66.1A.2 (2 Cum. Supp. 2018).).

[20] Pub. L. 110-245, 122 Stat. 1624 (2008).

[21] See International Tax Law supra note 18, at 166-168.

[22] See e.g., United States v. Pink, 315 U.S. 203 (1942); United States v. Belmont, 301 U.S. 324 (1937); Dames & Moore v. Regan, 453 U.S. 654 (1981). See Erwin Chemerinsky, Constitutional Law: Principles and Policies §§ 3.5.1 (4th ed., 2011).

[23] Sean Murphy, Principles of International Law 93 (2012).

[24] Id. at 94-95.

[25] Steven M. Barkan, Roy M. Mersky & Donald J. Dunn, Fundamentals of Legal Research 440-42 (9th ed. 2009).

[26] See Janis, supra note 14, at 58.

[27] Id.; Statute of the International Court of Justice, art. 38(1)(b), June 26, 1945, 59 Stat. 1055, 3 Bevans 1179, hereinafter Statute of the ICJ.

[28] Statute of the ICJ, supra note 27, art. 38(1)(c); See Marci B. Hoffman & Robert C. Berring, International Legal Research in a Nutshell, 2nd ed. 81-85 (2017) for a detailed explanation on the general principles of law.