The OECD in 2026: What Businesses Need to Understand

1. What the OECD Is

The OECD grew from the Organisation for European Economic Co-operation, created in 1948 to administer Marshall Plan aid. The Convention transforming the OEEC into the OECD was signed in Paris on 14 December 1960 and entered into force on 30 September 1961. The OECD has 38 members and works with more than 100 countries. Mathias Cormann has served as Secretary-General since 2021; his second and final five-year term began on 1 June 2026.

The 38 does not include Russia. Its accession process, opened in 2007 and postponed in 2014, was formally terminated by the OECD Council on 25 February 2022 in response to the full-scale invasion of Ukraine, and the OECD closed its Moscow office at the same time. Russia was a candidate, never a member.

Its work combines comparable data, policy analysis, peer review and standard-setting. That combination matters. A benchmark becomes more influential when governments measure themselves against it, publish the results and carry the standard into legislation, tax administration, public finance, procurement or corporate due diligence.

2. How OECD Standards Work

The OECD Council can adopt Decisions and Recommendations under Article 5 of the founding Convention. Decisions are legally binding on members that do not abstain, although under Article 6 no Decision binds a member until that member has complied with its own constitutional procedures. Recommendations are not legally binding, but they express a political commitment and are often monitored through reporting and peer review.

Separate conventions negotiated under OECD auspices, including the Anti-Bribery Convention, become binding international law for countries that ratify them. Other instruments influence business indirectly because national authorities, lenders, investors, customers and procurement teams use them as reference points.

3. Membership and Accession

Costa Rica became the 38th member in May 2021. Eight countries are now in formal accession processes. Accession is not a promise of membership by a stated date. Each candidate submits an Initial Memorandum setting out its position on the OECD's legal instruments, then undergoes in-depth review by some 25 technical committees, covering areas from investment and taxation to environment and labour. The OECD Council decides by consensus whether to issue an invitation once those reviews are complete, which gives every existing member a veto.

Dates are taken from the OECD Council decisions and accession roadmaps, checked on 25 September 2026. Progress since then differs widely. Romania reported its 24th of 25 committee opinions in April 2026 and Bulgaria its 18th of 25 in June 2026, while Argentina submitted its Initial Memorandum only in November 2025 and Thailand in December 2025. National target dates are not OECD completion dates and have been excluded. For a country-risk assessment, the stage each candidate has actually reached is a more reliable guide than the date its discussions opened.

4. The Major 2026 Tax Story

Pillar Two and the Side-by-Side Package

The OECD/G20 Inclusive Framework on Base Erosion and Profit Shifting brings together more than 145 countries and jurisdictions. Its Pillar Two rules are designed to apply a 15% minimum effective tax rate to large multinational groups, generally those with consolidated annual revenue of at least EUR 750 million. The rules operate through domestic legislation, not through a tax levied by the OECD.

On 5 January 2026, the Inclusive Framework approved the Side-by-Side package. It introduced a permanent Simplified Effective Tax Rate safe harbour, extended the transitional country-by-country reporting safe harbour by one year, introduced a Substance-Based Tax Incentive safe harbour and created safe harbours for groups whose ultimate parent is in a jurisdiction that meets specified minimum-tax conditions.

The package's political context also matters. On 11 September 2026, the US Treasury welcomed the revised GloBE Information Return as implementing “President Trump's Day One Executive Order”, stating that US-headquartered companies will remain subject to US global minimum taxes rather than “overlapping foreign regimes.” For compliance teams outside the United States, the practical point is that the Side-by-Side arrangement is a negotiated accommodation that each jurisdiction must still legislate, and its durability depends on continued political agreement rather than treaty commitment.

Where the Side-by-Side safe harbour applies, top-up tax is treated as zero for the Income Inclusion Rule and Undertaxed Profits Rule. It does not displace the primary taxing right of a jurisdiction operating a Qualified Domestic Minimum Top-up Tax. A qualifying group can therefore retain domestic top-up tax exposure in a low-tax jurisdiction even when IIR and UTPR exposure is reduced.

Priority, not just existence, is what explains this. A QDMTT has the first claim on a jurisdiction's own low-taxed income: once that jurisdiction taxes it up to 15% under its own domestic minimum tax, there is nothing left for the IIR or UTPR to reach. The Side-by-Side safe harbour reduces exposure under those two rules specifically; it was never going to touch a separate jurisdiction's prior claim on its own income, because the two mechanisms are not competing for the same tax.

Filing obligations can be independent of the amount owed. Belgium is a timely example. A group in scope must file an annual Belgian QDMTT return even where a safe harbour applies and no top-up tax is ultimately payable; groups within the scope of the IIR file a separate IIR return; and the GIR filing entity must be notified separately. After two extensions, the first Belgian deadline for these filings was deferred to 30 September 2026. Other jurisdictions set their own return, notification and GIR requirements, so group tax functions should check each one separately rather than treating “no tax due” as “nothing to file.”

The OECD framework sets qualification criteria and uses a central record. Businesses should check that record and the relevant national legislation rather than treating the package as a blanket exemption for every US-linked group.

National implementation is still moving. The Netherlands, for example, tabled a bill with its 2027 Tax Plan on 15 September 2026 to add the new safe harbours to its Minimum Tax Act, partly with retroactive effect. Groups should confirm how, and from when, each jurisdiction in which they operate gives effect to the package.

The 11 September Implementation Update

The most recent OECD development at the time of this review came on 11 September 2026, when the Inclusive Framework released:

• A framework for full peer reviews of domestic IIR, UTPR and QDMTT legislation.
• An updated GloBE Information Return incorporating the January simplifications, for fiscal years beginning on or after 31 December 2025.
• Additional guidance on explicitly conditional taxes and the use of local financial accounting standards where QDMTT and parent fiscal periods do not align.

For affected groups, this is a systems and data issue as much as a tax-policy issue. Reporting teams should map the revised GIR fields now, but wait for the revised XML schema, which the OECD said would follow shortly, and for local filing specifications before changing systems. They should also confirm which entity will file and reconcile local QDMTT calculations with group data.

Transfer Pricing and Customs: Two Regimes That Do Not Automatically Reconcile

The OECD Transfer Pricing Guidelines remain the global reference for applying the arm's length principle to cross-border transactions between associated enterprises. They affect the pricing and documentation of goods, services, financing, intellectual property and distribution arrangements. In June 2026, the OECD opened a consultation on revisions to Chapter VII concerning intra-group services; public comments were published on 24 August 2026 and a consultation meeting is scheduled for 9 November 2026 at the OECD Conference Centre in Paris.

Customs value and transfer price are governed by different legal frameworks, and the reason is a specific piece of case law. In Hamamatsu Photonics (Case C-529/16, 2017), the Court of Justice of the EU held that a retroactive transfer-pricing adjustment calculated on a residual-profit basis does not automatically justify adjusting a declared customs value, because customs valuation looks at the value of the specific imported goods, not a group's overall margin.

A downward adjustment can therefore produce a customs refund claim rather than an automatic correction, and an upward adjustment can create additional duty liability that customs authorities are free to pursue. A more recent ruling, Tauritus (Case C-782/23, 15 May 2025), narrows this in one respect: where a price adjustment is pre-agreed and objective, for example indexed to a published price or exchange rate written into the sales contract, the transaction value method can still apply.

5. Responsible Business Conduct

The OECD Guidelines for Multinational Enterprises on Responsible Business Conduct were updated in June 2023. They cover human rights, labour, the environment, bribery, consumer interests, disclosure, science and technology, competition and taxation. They ask businesses to conduct risk-based due diligence across operations, products, services and business relationships, including supply chains.

The Guidelines are backed by 52 governments: all 38 OECD members and 14 non-members. Each adherent must maintain a National Contact Point. NCPs promote the Guidelines and provide a non-judicial grievance mechanism for alleged non-observance. They cannot impose a fine, but they can offer mediation, publish statements and make recommendations. The OECD's database of specific instances now covers cases linked to activity in more than 100 countries and territories.

The regulatory picture has moved beyond voluntary expectations. On the OECD's own figures, 84% of OECD member countries, and 67% of all governments adhering to the Guidelines, have introduced due diligence-related regulation. That category is broad. It covers sustainability reporting laws, mandatory due diligence laws, and product or market-based rules, each with its own scope and duties. The practical step is to identify which specific laws apply to the company's products, operations and markets, and what each one requires, rather than assume a single standard.

The OECD Responsible Business Outlook 2026 gives this section practical weight. It assessed the 10,000 largest listed companies. Although 69% disclosed a commitment on at least one responsible-business issue, fewer than 20% reported assessing supplier risk against social or environmental criteria and only 7% reported integrating social supply-chain policy into purchasing practices. The gap between policy and purchasing evidence is where due diligence often fails, and where the applicable laws are increasingly likely to test it.

6. Anti-Bribery and Enforcement

The Convention on Combating Bribery of Foreign Public Officials in International Business Transactions entered into force in 1999. It is a binding treaty. Its 46 Parties must criminalise foreign bribery by their companies and nationals and must investigate, prosecute and sanction the offence under domestic law.

Implementation is monitored by the OECD Working Group on Bribery through successive peer-review phases. Country reports are public. They can show whether a jurisdiction has adequate laws, resources and enforcement practice. Businesses entering a market should use those findings as one input to country risk assessment, while remembering that weak public enforcement increases rather than reduces the need for strong internal controls.

Monitoring can also produce direct commercial signals. In July 2026, the Working Group took the exceptional step of warning that Türkiye's failure to implement key aspects of the Convention may necessitate increased due diligence over Turkish companies, citing long-standing gaps in its legal framework and enforcement. The warning concerns the state's implementation record, not the conduct of any individual company. It does, however, give commercial partners and lenders a documented reason to ask sharper questions about agents, intermediaries and public-sector counterparties.

Indonesia, Mauritius and Ukraine requested accession to the Convention in July 2025, and Ukraine's parliament gave first-reading approval to enabling legislation in May 2026. The OECD still reported 46 Parties at the time of this review, so none of the three should yet be described as a completed accession.

7. Trade Facilitation and Export Credit

Trade Facilitation Indicators

The OECD Trade Facilitation Indicators compare the design and operation of border processes across economies. They complement the WTO Trade Facilitation Agreement by examining areas such as information availability, advance rulings, appeal procedures, fees, document automation, agency co-operation and border governance. They are diagnostic indicators, not legally enforceable customs rules. Businesses can use them to test whether a delay reflects a company process, a specific authority or a wider border-system weakness.

Officially Supported Export Credits

The Arrangement on Officially Supported Export Credits is a gentlemen's agreement among its Participants. It disciplines the financing terms that governments and export credit agencies can support, including repayment periods, minimum premium rates and other conditions. The Arrangement is updated, and sector understandings can modify its terms for particular industries. Exporters should identify the current version and applicable sector rules before pricing a transaction that depends on public support.

In the EU, the Arrangement carries legal force. Regulation (EU) No 1233/2011 provides that its guidelines apply in the Union, and the Commission updates them by delegated act. On 7 September 2026, the Commission adopted a delegated regulation incorporating amendments to the Arrangement finalised on 26 January 2026, covering the civil aircraft sector understanding, the margin used to set Commercial Interest Reference Rates, and climate-related export credits. It enters into force 20 days after publication in the Official Journal.

8. What Businesses Should Do Now

The WTO, WCO and OECD at a Glance

Membership figures are current to the latest ECTM review on 25 September 2026.