Direct Tax Laws & International Taxation · Application and Interpretation of Tax Treaties

Interpretation of Tax Treaties and the Vienna Convention

Updated 5 October 2026 · Fact-checked

Tax treaty interpretation means finding the meaning of treaty words using Articles 31 and 32 of the Vienna Convention: good faith, ordinary meaning, context, object and purpose. Undefined terms go to Article 3(2), which uses domestic law unless the context requires otherwise. To answer, state the rule, apply it to the facts, then conclude.

Understand Interpretation of Tax Treaties and Vienna Convention

A tax treaty is an agreement between two countries. It is not an ordinary domestic law. So its words are read by international law rules, not by the usual rules for reading a tax statute. The main source is the Vienna Convention on the Law of Treaties, 1969.

Article 31 is the general rule. A treaty is read in good faith, in the ordinary meaning of its terms, in their context and in light of its object and purpose. Context includes the text, preamble and annexes, plus related agreements and later practice between the parties. Article 32 gives supplementary means, such as preparatory work (travaux préparatoires). You use these only to confirm the meaning, or when Article 31 leaves it ambiguous, obscure or absurd.

Many treaty terms are not defined. Article 3(2) of the OECD and UN Models handles this. Under both Models, a term not defined in the treaty has the meaning it has under the law of the State applying the treaty, as at the time of application, unless the context requires otherwise. Under the Models, the meaning under that State's tax laws prevails over the meaning under its other laws. The words 'unless the context otherwise requires' can switch off the domestic meaning. Treaty wording can vary. Some treaties fix the meaning as at the date of signing, so read the Article 3(2) of the treaty in the question.

The OECD Commentary is not binding. Indian courts and tribunals treat it as persuasive, especially for treaties that follow the OECD Model. The UN Model commentary matters for treaties based on the UN Model. For a treaty signed before a commentary change, be careful: later commentary is generally treated as less useful than the commentary current when the treaty was signed. Its weight is debated, so say it is persuasive, not binding.

In India, section 90(2) of the Income-tax Act, 1961 lets the assessee choose the more beneficial of the Act or the treaty. The corresponding provision in the Income-tax Act, 2025 is section 159. A treaty gives relief. It does not create a charge that domestic law does not impose.

Two Supreme Court rulings are standard in exams. In Union of India v. Azadi Bachao Andolan (2003), the Court upheld the validity of the CBDT circular on tax residency certificates under the India-Mauritius treaty. It treated the tax residency certificate (TRC) as sufficient evidence of residence and beneficial entitlement to the treaty benefit. It held that treaty shopping is not per se illegal. It relied on section 90(2), under which the treaty prevails where it is more beneficial to the assessee. Vodafone International Holdings BV v. Union of India (2012) concerned the indirect transfer of shares of an Indian company through the sale of an overseas holding company. The Court held that, under the law as it then stood, the transfer was not taxable in India. It said that tax planning within the law is permitted, that a genuine structure is respected and that a sham or colourable device can be looked through. It observed that Azadi Bachao Andolan was not inconsistent with this look-through approach to sham structures, and did not treat it as needing to be overruled. Vodafone is not mainly a treaty interpretation case. Also note that the retrospective amendment by the Finance Act, 2012 overrode the outcome for domestic law purposes by taxing such indirect transfers.

Key rules to remember

Vienna Convention, Article 31 (general rule): Interpret in good faith = ordinary meaning of terms + context + object and purpose; Context includes text, preamble, annexes, related agreements and instruments, and later agreement or practice between parties.
Vienna Convention, Article 32 (supplementary means): Use preparatory work and circumstances of conclusion only to confirm Article 31 or if meaning is ambiguous, obscure, manifestly absurd or unreasonable; Article 32 does not override a clear Article 31 result.
Article 3(2) of the OECD/UN Model: Undefined term = meaning under the law of the applying State at the time of application, unless the context otherwise requires; Under the Models, tax law meaning prevails over meaning under other laws. Context can displace the domestic meaning. Treaty wording may vary, and some treaties freeze the meaning at signing.
Treaty versus domestic law in India: Section 90(2) of the 1961 Act (section 159 of the Income-tax Act, 2025): assessee may choose the more beneficial of the Act or the treaty; Treaty cannot be used to impose a tax burden that the domestic law does not impose.
Weight of OECD Commentary: OECD Commentary = persuasive aid, not binding law; Strongest where the treaty follows the OECD Model and the commentary existed or is consistent with the text at signing.

How to solve Interpretation of Tax Treaties and Vienna Convention questions

Use the same sequence for any question on treaty interpretation, whether it asks for a rule, a case or a fact-based problem.

1Identify the term or provision in dispute and the treaty involved. Note whether it follows the OECD or UN Model.
2Check if the treaty itself defines the term (Article 3 or the specific article). If yes, apply that definition.
3If not defined, apply Article 3(2): use the domestic tax law meaning, then ask if the context requires a different meaning.
4Apply Vienna Convention Article 31: ordinary meaning, context, object and purpose, read in good faith.
5Use Article 32 materials or OECD/UN Commentary only as supporting aids, and say they are persuasive, not binding.
6Bring in the relevant ruling: Azadi Bachao Andolan for treaty shopping and treaty benefit, Vodafone for substance and genuine tax planning.
7Compare treaty and domestic law for the more beneficial position, as per section 159 of the Income-tax Act, 2025.
8Conclude clearly in provision, facts and conclusion form.

Quickest way: Four-line answer frame

When to use it: Use when a 5 or 6 mark written answer or a case MCQ asks how a treaty term or provision is to be read.

Line 1: State Article 31 of the Vienna Convention in one sentence.
Line 2: State Article 3(2) if the term is undefined, with the context exception.
Line 3: Mention OECD Commentary as persuasive and the relevant case (Azadi Bachao Andolan or Vodafone) in one sentence each.
Line 4: Apply to the facts and give a one-line conclusion.

Common mistakes in Interpretation of Tax Treaties and Vienna Convention

Saying the OECD Commentary is binding on Indian authorities.
Students see courts quoting it often and assume it has legal force.
Fix: Write that it is a persuasive aid to interpretation, with weight depending on the treaty text and the timing of the commentary.
Applying the domestic meaning under Article 3(2) without checking the context.
Students remember only the first half of the rule.
Fix: Always add 'unless the context otherwise requires' and test whether the treaty text or purpose points to a different meaning.
Using Article 32 supplementary means first.
Students think preparatory work is the best evidence of intent.
Fix: Start with Article 31. Turn to Article 32 only to confirm a result or resolve ambiguity.
Stating Azadi Bachao Andolan as allowing all treaty abuse.
The ruling is summarised as 'treaty shopping is legal'.
Fix: Say treaty shopping is not per se illegal and the treaty benefit was upheld on the facts. Add that sham or colourable devices can still be disregarded, as Vodafone discusses.
Treating Vodafone as a case that rejected Azadi Bachao Andolan, or as a pure treaty interpretation case.
Both deal with structures and are taught separately.
Fix: Present Vodafone as an indirect transfer case that respects genuine structures and looks through sham ones. Add that the Finance Act, 2012 retrospective amendment overrode its outcome for domestic law.
Assuming a treaty can create a tax liability that domestic law does not.
Students read 'treaty overrides' as 'treaty always wins'.
Fix: State that the assessee may choose the more beneficial of the Act or the treaty. Treaty gives relief but does not impose a new charge.

Worked examples

Example 1

Case: A company resident in Country X earns fees from an Indian company. The India-X treaty, a hypothetical one, taxes 'fees for technical services' but does not define that term. The Income-tax Act has a wide meaning for 'fees for technical services'. The treaty text and its protocol, which forms part of the treaty, suggest a narrower sense. The Indian company asks which meaning applies.

Show the solution

Provision: The term 'fees for technical services' is undefined in the treaty, so Article 3(2) applies. India gives the term its domestic tax law meaning, unless the context otherwise requires.
Facts: The domestic Act defines the term widely, but the treaty text and protocol point to a narrower sense.
Apply Article 31 of the Vienna Convention: read the term in good faith, in its ordinary meaning, in context and in light of the treaty's object and purpose. The protocol forms part of the treaty, so it is part of the context.
Because this context points to the narrower sense, the 'unless the context otherwise requires' exception in Article 3(2) is met. The domestic definition is displaced.
OECD or UN Commentary may be used as a persuasive aid, but it cannot override the treaty text.

Answer: The narrower meaning of 'fees for technical services' shown by the treaty text and protocol applies, because the context under Article 3(2) requires a meaning different from the domestic definition.

Example 2

Case: A Mauritius company holds Indian shares. It holds a tax residency certificate issued in Mauritius. The tax officer says the company was set up only to claim treaty benefit and denies relief, but shows no evidence that the structure is a sham. Advise on the position based on case law.

Show the solution

Provision: Treaty is read under Article 31 in good faith and ordinary meaning. Benefit follows the treaty text.
Case law: Azadi Bachao Andolan held treaty shopping is not per se illegal and upheld the circular accepting the tax residency certificate as sufficient evidence of residence and beneficial entitlement to treaty benefit.
Vodafone held that a genuine structure is respected and tax planning within law is allowed. A sham or colourable device can be looked through. The Court observed that Azadi Bachao Andolan was not inconsistent with this approach.
Facts: The company holds a tax residency certificate. The officer's only ground is that the company was set up to obtain treaty benefit, and he has not shown that it is a sham.
Check domestic anti-avoidance rules and any limitation of benefit clause in the treaty, which may apply separately.

Answer: The denial is not sustainable merely because the company was set up to get treaty benefit. Unless the officer proves a sham or an anti-abuse provision applies, the treaty benefit should be allowed on the strength of the tax residency certificate.

Exam tips

Write Article 31 and Article 32 separately and in order. Examiners reward the sequence.
Always attach the phrase 'unless the context otherwise requires' when you write Article 3(2).
For case-law answers, give the court, the year, the holding and one line of application to the facts.
Call the OECD Commentary persuasive, never binding, and mention it only after the treaty text.
In MCQs, watch for options that overstate Azadi Bachao Andolan as permitting every form of treaty abuse.

Practice questions from Application and Interpretation of Tax Treaties

Interpretation of Tax Treaties and Vienna Convention: frequently asked questions

What does the Vienna Convention say about interpreting tax treaties?

Article 31 requires interpretation in good faith, in the ordinary meaning of the terms, in their context and in light of the treaty's object and purpose. Article 32 allows preparatory work as a supplementary aid. Indian courts apply these principles to tax treaties.

What was held in Azadi Bachao Andolan?

The Supreme Court upheld the validity of the CBDT circular on Mauritius tax residency certificates. It treated the certificate as sufficient evidence of residence and beneficial entitlement, and held that treaty shopping is not per se illegal. It relied on section 90(2), under which the assessee can choose the more beneficial of the Act or the treaty.

How does Vodafone differ from Azadi Bachao Andolan?

Vodafone concerned the indirect transfer of shares. It stressed looking at the transaction as a whole and respecting genuine structures, while allowing sham or colourable devices to be looked through. The Court observed that Azadi Bachao Andolan was not inconsistent with this approach. The Finance Act, 2012 amendment later overrode its outcome for domestic law.

How are undefined terms treated under Article 3(2)?

Under the OECD and UN Models, the applying State uses the meaning under its own law at the time of application, unless the context requires otherwise. Treaty wording may vary, and some treaties fix the meaning at signing. Always test whether the treaty context points to a different meaning.

Is the OECD Commentary binding in India?

No. It is a persuasive aid, mainly for treaties that follow the OECD Model. Its weight depends on the treaty text and on when the relevant commentary was issued.