The Advanced Diploma in International Taxation (ADIT) is a specialist postgraduate qualification awarded by the Chartered Institute of Taxation (CIOT). It is designed for tax professionals who advise on international tax matters, and it is recognised globally.

This module looks at the international tax system as a whole - not the domestic tax rules of any single jurisdiction. The focus is on the framework that governs how countries allocate taxing rights between them: tax treaties, transfer pricing, anti-avoidance measures, and the evolving OECD and UN standards that shape modern international tax policy.

It is particularly well-suited to:

• Tax advisers in practice who work with cross-border clients or transactions
• In-house tax professionals in multinational businesses
•  Those working in transfer pricing, corporate tax or financial services who want to develop their understanding of the international framework
• Tax professionals seeking to progress their career or deepen their technical knowledge in a structured way

If international tax is a growing part of your work, or an area you want to move into, this module gives you the conceptual and technical foundation to do that.

The syllabus is broad, but it is coherently structured. It is divided into six parts, with the exam weighted to reflect the relative importance of each.

This covers the foundational concepts: jurisdiction to tax, the distinction between source and residence, how states determine tax residence for individuals and companies, the causes of international double taxation, and the methods used to relieve it. This section also touches on the history of international tax law and the roles of the OECD, the G20 and the United Nations.

This is the largest part of the syllabus, and for good reason. Double taxation conventions (DTCs) are the primary mechanism through which states manage cross-border taxation. You will study the OECD Model Tax Convention (OECD MTC), comparing and contrasting with the UN Model Double Taxation Convention (UN MTC). You will look at how double tax treaties are interpreted, how key articles apply in practice, and how treaty abuse is addressed.

The syllabus reflects the current state of international tax. Pillar One (reallocation of taxing rights) and Pillar Two (the global minimum tax) are both examined. We discuss the policy rationale behind the BEPS 2.0 measures, looking at the current state of implementation around the world and alternative options to meeting the challenges of the digital economy. 

This part covers the arm's length principle, the OECD Transfer Pricing Guidelines, transfer pricing methodologies, advanced pricing agreements, along with the impact of BEPS Actions 8–10 and 13. It also covers thin capitalisation rules and restrictions on interest deductibility under BEPS Action 4.

This is a significant part of the paper. This covers harmful tax practices, controlled foreign company legislation, exchange of information, the Common Reporting Standard, and BEPS Actions 2, 3, 5, 11, 12 and 15, among others. Transparency and anti-avoidance are recurring themes throughout.

This final section covers indirect taxes in an international context, cross-border mergers and emerging topics such as digital currencies and artificial intelligence in taxation.

The permitted texts - including the OECD MTC, the UN MDTC, the OECD Transfer Pricing Guidelines and the Vienna Convention on the Law of Treaties - can be brought into the exam. Knowing how to use them effectively under exam conditions is part of the preparation.

The exam is three hours and 15 minutes long and is sat online, in a location of your choice, at a set date and time. The June 2026 exam takes place on Tuesday 9 June.

It is divided into two sections:

• Section A comprises three essay questions, worth 25 marks each. Candidates must answer at least two.
• Section B offers two case study questions, each worth 25 marks.

Candidates must answer four questions in total. This means you can choose either three essay questions from Section A and one case study from Section B, or two essay questions from Section A and both case studies from Section B.

The essay questions in Section A typically focus on conceptual and analytical issues. For example, the interpretation of treaty provisions, the operation of BEPS measures, or the principles underlying a particular area of international tax law. Section B requires candidates to work through a detailed fact pattern, identify the treaty issues it raises, and set out a reasoned analysis. These questions draw on the same technical knowledge as the essays but test your ability to apply that knowledge to a specific scenario.

Past papers are a central part of preparation. They reveal the style of questioning, the level of technical depth expected, and the topics that recur. Reviewing past papers early in your studies helps you understand what the examiners are looking for and how to structure your answers.

It is. The overall CIOT pass rate for Principles of International Tax has ranged from around 37% to 61% in recent sittings. That reflects the depth and breadth of the syllabus, and the level of analysis required in the exam itself.

That said, candidates who prepare consistently - working through the material steadily, practising past paper questions, and using the revision phase effectively - are well placed to pass. The exam rewards structured, clear analysis rather than memorisation or regurgitation from the Permitted Texts.

At ExtraTax Training, our students passed at a rate of 88% in June 2025 and 100% in December 2025. Structured support and consistent preparation make a significant difference.

For the June 2026 sitting, the ExtraTax Training course runs as follows.

Tuition phase
Ten weekly tuition classes run on Tuesdays from 4pm to 6:30pm, starting on Tuesday 3rd March. There are also two additional Friday booster sessions to revisit key topics.

Before the first class, students are asked to complete some pre-course reading. This is the opening chapters of Principles of International Taxation by Lynne Oats, which is available through the Bloomsbury International Tax Service included in your course package.

Each week, following the class, students work through a past paper assignment on the topic covered. This builds the habit of applying what you have learned before the material accumulates.

Revision phase
After the tuition classes, the focus shifts to revision. There are two weekend revision days, structured around past paper questions, as well as a pre-revision mock exam and a post-revision mock exam. The mock exams are an important part of preparation. They test not just knowledge but time management and the ability to produce structured answers under pressure.

Classes are delivered live on Zoom via our online learning platform. Recordings are made available after each session, which is helpful if you are unable to join live or want to go back over a topic.

Study materials
Your course package includes access to the Bloomsbury International Tax Service, which is the primary study resource for this module. It contains the set text by Lynne Oats, alongside the permitted texts relevant to the exam.

If you are planning to sit in June 2026, there are two important CIOT deadlines to note:

• 2nd March 2026 — deadline to register as an ADIT student with the CIOT (required before you can enter for an exam)
• 16th March 2026 — deadline to enter for the June 2026 ADIT exams

These are CIOT deadlines and are fixed. It is your responsibility to register and enter in time.

For your career
ADIT is a globally recognised qualification. For tax professionals whose work involves cross-border matters, holding an ADIT qualification, or even a certificate in a specific module, demonstrates a level of technical knowledge that goes beyond generalist tax training.

For your day-to-day practice
The Principles of International Tax syllabus covers the concepts and frameworks that underpin most international tax work: treaty interpretation, transfer pricing, anti-avoidance, and the evolving BEPS framework. Studying the module systematically gives you a more confident and grounded understanding of the issues you encounter in practice.

Flexibility
Because you can sit the paper as a standalone certificate, you can benefit from having your knowledge recognised without committing to the full qualification. If you later decide to continue, you have at least five years to complete ADIT.

Small group classes
The ExtraTax Training course runs as small group classes, which means there is genuine interaction in the sessions. We encourage you to ask questions, and the tutor can respond to what the group needs. Students consistently tell us that attending the live sessions, including the revision days, was important to their success.

Studying for a professional qualification alongside a full-time role requires focus and organisation. The ExtraTax Training team, including Kristen Gillanders, who looks after client relations from the point of booking through to results, is there to help with the practical side of things. If you have questions about the course, the CIOT registration process, or anything else, please get in touch.

If you would like to join the ADIT Principles of International Tax classes or one of our other ADIT courses, please get in touch with the ExtraTax Training team by emailing info@extrataxtraining.com or calling +44 (0)28 9590 5990.