OECD Pillar Two in Thailand.

For global information on OECD Pillar Two and the global minimum tax for multinational groups in all markets, see Acclime Group’s guide.

Thailand has enacted the OECD’s Pillar Two Global Anti-Base Erosion (GloBE) Rules through the Emergency Decree on Top-up Tax, B.E. 2567 (2024), introducing the 15% global minimum effective tax rate for large multinational enterprise (MNE) groups. The Decree applies for fiscal years beginning on or after 1 January 2025 and implements all three charging mechanisms, the Qualified Domestic Minimum Top-up Tax (QDMTT, referred to domestically as the Domestic Top-up Tax), the Income Inclusion Rule (IIR) and the Undertaxed Profits Rule (UTPR), which take effect simultaneously.

The Decree was published in the Royal Gazette on 26 December 2024, with the detailed computational and administrative rules following through subordinate legislation. The first GloBE filings, covering fiscal years ending 31 December 2025, fall due on 30 June 2027. This guide focuses on Thailand’s implementation, filing obligations and local considerations.

At a glance

Local summary

Thailand has adopted all three GloBE charging mechanisms simultaneously through the Emergency Decree on Top-up Tax. Where the jurisdictional effective tax rate (ETR) in Thailand is below 15%, additional Top-up Tax may arise and be collected through the QDMTT, IIR or UTPR. The QDMTT, known domestically as the Domestic Top-up Tax, allows Thailand to collect the Top-up Tax on low-taxed Thai profits before such tax may be imposed by another jurisdiction under the IIR or UTPR.

Scope and key concepts

The GloBE Rules apply to MNE groups meeting the EUR 750 million consolidated revenue threshold. In Thailand, all Constituent Entities located in the country that are part of an in-scope group fall within scope (including subsidiaries, branches and in-scope joint ventures) where the global group meets the threshold, even if the Thai entity’s own revenue is much lower.

How the mechanisms apply depends on where the Ultimate Parent Entity (UPE) sits. Where the UPE is outside Thailand, Thailand’s QDMTT takes priority over Thai-source profits, so a Thai entity typically pays any Top-up Tax locally under the QDMTT. Where the UPE, an intermediate parent or a partially-owned parent entity is in Thailand, the IIR applies to low-taxed foreign group entities, with the UTPR operating as a backstop where Top-up Tax has not been fully collected elsewhere. For the Domestic Top-up Tax and the UTPR, liabilities are allocated proportionally among Thai Constituent Entities based on their GloBE Income. Subject to conditions, the group may designate a single Thai entity to file and pay, although all Thai entities remain jointly liable.

Local deviations

Based on our review, Thailand’s Pillar Two framework generally aligns with the OECD GloBE architecture, and no material substantive deviations have been identified to date. Detailed computational and administrative rules continue to be issued through subordinate legislation (Royal Decrees and Ministerial Regulations), which in-scope groups should monitor.

Compliance and filing obligations

In-scope groups with Thai Constituent Entities are subject to the filing, payment and reporting requirements set out below. All filings are made to the Thai Revenue Department, and operate separately from the ordinary corporate income tax return.

Key deadlines

The three filings

Notification

In-scope Thai Constituent Entities must notify the Revenue Department that they belong to an in-scope MNE group. An exemption may apply in certain cases, for example where the notification information is available to the Revenue Department through another channel.

GloBE Information Return (GIR)

The GIR may be filed by each Thai Constituent Entity, or the local obligation may be satisfied where the UPE or a designated surrogate entity files the GIR in a jurisdiction that has an effective exchange-of-information arrangement (such as a Qualifying Competent Authority Agreement) with Thailand. Local filing obligations should be reviewed for each group structure, as filing directly in Thailand remains the more reliable route where the position is uncertain.

Top-up Tax Return and payment

The Top-up Tax Return reports the liability arising under the QDMTT, IIR and/or UTPR. For the Domestic Top-up Tax and the UTPR, the liability is allocated proportionally among Thai Constituent Entities based on GloBE Income. Subject to conditions, the group may designate one Thai entity to file and pay, with the Revenue Department notified within 15 months after the last day of the UPE’s fiscal year, though all Thai entities remain jointly liable. Assessed top-up tax may be paid in instalments over a three-month period.

Transitional safe harbours

Thailand has not yet adopted the OECD transitional safe harbours. The Revenue Department is expected to issue further guidance through subordinate legislation, including on safe harbours and the de minimis rule. Until then, in-scope groups should plan on the basis that the full GloBE calculation applies to their Thai operations.

Tax incentive impact

Pillar Two does not remove Thailand’s tax incentives, but it neutralises their benefit for large in-scope groups. Incentives that reduce the effective tax rate below 15%, including Board of Investment (BOI) tax holidays and reduced rates, may be offset by Top-up Tax under the QDMTT, IIR or UTPR, effectively recovering the benefit the incentive was intended to confer. Entities that are not part of an in-scope MNE group continue to benefit from BOI incentives as before.

In response, the BOI and the Ministry of Finance have moved to redesign affected incentives. In November 2025 they announced changes to the National Competitiveness Enhancement Act to introduce a Qualified Refundable Tax Credit (QRTC), an OECD-recognised mechanism offered as an alternative measure for MNEs affected by the Decree. The Substance-Based Income Exclusion may also provide partial relief based on local payroll and tangible assets.

Monitoring, audit and disputes

The Thai Revenue Department administers and monitors compliance with the top-up tax regime, which is reported separately from the ordinary corporate income tax return. A late or inaccurate GIR can create inconsistencies with data filed elsewhere and trigger Revenue Department queries. Because the detailed rules are still being finalised through subordinate legislation, in-scope groups should monitor developments and keep their data and calculations under review. Groups may pursue the usual dispute resolution routes against assessments or collection actions arising from Pillar Two.

Key local issues

Penalties under the top-up tax regime are significant, which makes accurate and timely filing a priority:

Local contact

For advice on how Pillar Two applies to your group’s Thai operations, please contact Acclime Thailand about their tax services regarding OECD Pillar Two.