Is There Really an International Tax System?

International taxation has become more prominent — and more complex.

But as governments introduce new layers of rules and international coordination intensifies, a more fundamental question emerges: is there really such a thing as an international tax system?

In this conversation with Tax Academy of Singapore, Professor H. David Rosenbloom draws on nearly six decades of experience in international taxation to examine some of the assumptions shaping tax policy today.

From Pillar Two and treaty dispute resolution to Singapore’s role in international tax discussions, the growing complexity confronting multinational businesses and the impact of artificial intelligence on the tax profession, Professor Rosenbloom offers a characteristically candid perspective on where international taxation may be heading.

Five perspectives from Professor David Rosenbloom

International taxation is becoming more prominent, but also more complex.

In this conversation with Tax Academy of Singapore, Professor H. David Rosenbloom draws on nearly six decades of experience in tax matters to reflect on some of the fundamental questions confronting international taxation today — from Pillar Two and tax treaties to national sovereignty, Singapore’s role in global tax discussions and the future of the tax profession.

1. Is there really an “international tax system”?

One of Professor Rosenbloom’s most fundamental observations is also one of the simplest: he is sceptical that there is, in fact, a single international tax system.

Instead, he sees the cross-border policies of individual countries interacting with one another. Countries continue to make their own decisions about whom and what they tax, even as treaties, international standards and coordinated initiatives increasingly connect national tax systems.

That distinction matters because it changes how international tax policy is understood. Coordination may be necessary, but it does not remove the underlying national systems through which taxation ultimately operates.

For Professor Rosenbloom, this also makes simplicity an important policy objective. Rather than continually tailoring increasingly complex rules to different taxpayer circumstances, he argues for rules that can be understood and practically administered by tax authorities.

“I don't really think there is an international tax system.”

2. Pillar Two: solving a problem or adding another layer of complexity?

Professor Rosenbloom makes no secret of his scepticism towards Pillar Two.

He points particularly to the additional complexity created by the rules and questions whether that complexity is solving the right problem — or indeed a clearly defined problem at all.

His comments raise a broader policy question extending beyond Pillar Two itself: how much complexity should international coordination create in pursuit of a policy objective?

This question becomes increasingly important as new international rules are layered on top of existing domestic laws, treaties and administrative requirements.

Later in the conversation, Professor Rosenbloom returns to this concern from the perspective of businesses. In his view, multinational enterprises are operating in an increasingly sophisticated environment in which new rules continue to be added to old ones.

His conclusion is straightforward:

“The rules just don't have to be this hard.”

Explore further

Professor Rosenbloom examines these tensions in greater depth in International Tax Policy Between National Sovereignty and Global Coordination, drawing on his session at Tax Academy's Masterclass with Professor David Rosenbloom and Professor Dr René Matteotti.

Read the Perspectives & Insights article

3. Tax treaties remain important — perhaps more than ever

Despite his scepticism towards some developments in international tax policy, Professor Rosenbloom remains clear about the continuing importance of tax treaties.

A key reason is dispute resolution.

Tax treaties provide access to the Mutual Agreement Procedure (MAP), through which the competent authorities of treaty partners can attempt to resolve cases involving cross-border taxation.

For Professor Rosenbloom, this ability to bring jurisdictions together to address international tax disputes remains crucial.

Rather than becoming obsolete as the international tax landscape changes, he suggests that tax treaties may now be more important than ever.

This becomes particularly significant as businesses operate across more jurisdictions and increasingly complex rules interact with one another. International coordination is not only about agreeing on rules; it also requires workable mechanisms for addressing disagreements when national tax systems collide.

4. Singapore has a voice in international tax debates

What influence can a small, open economy such as Singapore have on international taxation?

Professor Rosenbloom’s answer is encouraging: Singapore already plays an important role.

He observes that Singapore is regarded internationally as a significant jurisdiction in taxation. The question, therefore, is less about whether Singapore has a voice and more about finding the appropriate forums through which its positions and perspectives can be articulated.

The conversation also touches on whether there is a common “Asian perspective” in international taxation.

Professor Rosenbloom cautions against treating Asia as a single bloc. Countries have different national interests, and the tax priorities of Singapore, India or other Asian economies need not be identical.

At the same time, he sees Asian voices as being represented in international tax discussions.

The implication is an important one: meaningful international tax dialogue requires space for different national perspectives, rather than assuming that countries within a region necessarily approach tax policy in the same way.

5. In the age of AI, judgment still matters

The conversation closes by looking beyond tax rules to the future of the tax profession.

As artificial intelligence makes technical information increasingly accessible, what will distinguish an exceptional tax professional?

Professor Rosenbloom highlights the ability to think clearly, communicate effectively and write well.

Above all, however, he places emphasis on judgment.

Technical knowledge and technology will continue to matter, but tax professionals are often called upon to assess uncertain situations, understand competing considerations and form a view about how a problem may develop. Professor Rosenbloom does not see technological change as removing that responsibility.

He sees clear potential for AI in working with large volumes of information — including data-intensive areas such as transfer pricing — while cautioning against allowing it to substitute for human thinking.

When asked what younger professionals should learn beyond tax, his response is particularly succinct:

“How to write.”

And when looking towards the next generation of international tax leaders, he emphasises another quality: intellectual nimbleness.

Tax professionals need to remain capable of questioning assumptions and looking at the same problem from different perspectives rather than simply adopting the views of those around them.

A career perspective on a changing international tax landscape

Taken together, Professor Rosenbloom's observations do not offer a blueprint for a new international tax system.

They offer something arguably more useful: a way of questioning how that system is developing.

As international tax becomes more interconnected, policymakers, businesses and professionals may need to continually ask:

• What problem is a new rule intended to solve?

• Is greater complexity justified by the outcome it seeks to achieve?

• How do internationally coordinated rules interact with fundamentally national tax systems?

• What happens when countries disagree?

• And as technology becomes more capable, which decisions should continue to depend on human judgment?

For Professor Rosenbloom, international taxation has changed enormously over the course of his career. What has grown most significantly is not simply the volume of rules, but the recognition of international tax as an important subject of policy and analysis.

The challenge now is determining how that growing attention translates into an international tax environment that remains workable in practice.

About Professor H. David Rosenbloom

Professor H. David Rosenbloom is an international tax practitioner and academic with nearly six decades of experience in tax matters.

He served as International Tax Counsel and Director of the Office of International Tax Affairs at the United States Department of the Treasury from 1978 to 1981 and has advised organisations including the US Treasury, OECD and World Bank on tax policy matters.

Professor Rosenbloom also had a longstanding association with New York University School of Law, where he served as Director of the International Tax Program and as James S. Eustice Visiting Professor of Taxation before retiring from those roles in May 2025.

His work has spanned international tax policy, tax treaties, transfer pricing, international tax controversies and the interaction between national tax systems.