Since the implementation of the Trade Competition Act, B.E. 2560 (2017) (TCA) in October 2017, Thailand’s merger control framework has exhibited notable stability; there were no significant amendments or substantial shifts in the regulatory approach in 2025. The TCA faced some challenges at the time of initial implementation due to ambiguities in interpretation and application. However, enhanced clarity about merger filing procedures has been attained through rulings issued by the Trade Competition Commission (“Commission”).

Overview of Merger Filing Process in Thailand

In Thailand, a merger filing is required when a business operator merges with another business operator. It is important to note that not all entities qualify as “business operators” under the TCA: the designation is limited to vendors, producers engaged in sales, individuals who place orders or import goods into Thailand for sale, purchasers involved in the production or resale of goods, and service providers operating within a business framework. Consequently, a holding company does not fall within the classification of “business operator” and may not be subject to the merger filing requirements unless it controls subsidiaries that meet the definition of “business operator”. The Commission has also determined that a business operator must either be established in Thailand or have a subsidiary company based in Thailand. Based on this limited interpretation, it is not necessary to submit a merger filing in the event of a merger involving a foreign entity that does not have a subsidiary in Thailand, even if it generates income in Thailand.

For purposes of merger control, a “merger” is triggered if a transaction meets the following criteria.

• A consolidation of producers with producers, distributors with distributors, producers with distributors, or service providers with service providers, resulting in one business that continues and another that ceases to exist, or the formation of a new business.
• An acquisition of part or all of the assets of another business, with the goal of controlling business policy, management or administration. Specifically, acquiring assets used in the ordinary course of business from another operator, in an amount equal to more than 50% of the total value of the transferring operator’s assets, based on the relevant operator’s most recent fiscal year accounts, is classified as the purchase of assets for the purpose of controlling business policy, administration or management. The value of the assets acquired is determined based on their book value as of the date of the agreement or acquisition, as applicable.
• The acquisition of part or all of the shares of another business, whether conducted directly or indirectly, with the goal of gaining control over business policy, management or administration, including:
1. in the case of a Thai listed company, the acquisition or obtaining of shares, warrants or other securities convertible into shares on any given day, resulting in an increase in the total voting rights held in a business operator subject to the Securities and Exchange Act to 25% or more; or
2. in other cases, the acquisition or obtaining of shares with voting rights, on any given day, resulting in an increase in the total voting rights held in another business operator to more than 50%.

With regard to this last bullet point, where the acquiring party is an individual business operator, any acquisitions made by the acquiring party’s spouse are aggregated for purposes of evaluating relevant thresholds. Where the acquiring party is a legal entity, acquisitions made by individuals or legal entities that hold more than 30% of the total voting rights in the acquiring entity, along with acquisitions made by related business operators that possess policy influence or controlling power over the acquiring entity, are aggregated with those of the acquirer for evaluation purposes. It is also essential to clarify that the Commission currently interprets the “Securities and Exchange Act” to mean the Thai Securities and Exchange Act. Consequently, in the event of foreign-to-foreign mergers involving companies listed overseas, a merger is triggered when the acquiring entity obtains 50% or more of the total issued shares of the foreign listed company, rather than the 25% threshold referenced above.

The Thai merger control framework is organised into two distinct regulatory phases: pre-merger approval and post-merger notification. This dual structure reflects a strategic effort to balance the prevention of anti-competitive practices with support for legitimate business consolidations. The applicable phase is determined based on a substantive evaluation of the market impact: specifically, whether the proposed merger is likely to create or strengthen a “dominant position” in a market (per the criteria below), or whether it is merely a “merger that may significantly reduce competition in a market”.

According to the TCA, a “merger that may significantly reduce competition in a market” is defined by a specific quantitative threshold. When the combined sales turnover of an acquirer, target company or merging parties collectively meets or exceeds THB1 billion in a particular market in Thailand, and the transaction does not create a monopoly or lead to the emergence of a “dominant position”, it activates the requirement for post-merger notification. This threshold-based approach is designed to capture only those transactions that possess the potential to materially influence competitive dynamics, thereby ensuring that regulatory attention is appropriately directed toward mergers with substantial economic significance.

The calculation of sales turnover is comprehensive, and encompasses not only the merging entities but also all subsidiaries that have policy or controlling power relationships. This extensive definition is designed to prevent the circumvention of regulatory requirements through intricate corporate structures or indirect control mechanisms.

It is also important to note that the Commission’s interpretation of the “markets relevant for merger filings” is that any market in which the relevant party or parties’ revenue equals or exceeds THB1 billion will be taken into account, whether or not the market otherwise qualifies as a merging market. This broad interpretation has led to misunderstandings in connection with cross-border transactions, as entities may not be aware that a merger filing could be triggered even in situations that do not pertain to the intended business activities. Thus, when either the acquirer group or the target group generates revenue of THB1 billion or more in a particular market in Thailand, there is a stringent obligation to submit a post-merger notification within seven days after completion of the merger. This limited reporting timeframe emphasises the Commission’s dedication to prompt oversight.

By contrast, when a merger involves an entity that possesses a “dominant position”, or is likely to acquire one as a result of the merger, the regulatory framework requires pre-merger approval. This approach reflects a more cautious perspective, which acknowledges the increased risks associated with market dominance. By enforcing a higher level of scrutiny prior to the approval of these mergers, the regulatory Commission seeks to prevent the consolidation of market power that could have an adverse effect on consumer welfare and impede competition. Overall, the Thai regulatory framework utilises a sophisticated, risk-based method of merger regulation, which was meticulously designed to address varying levels of competitive threat.

If an acquirer fails to submit a merger filing and the authorities subsequently become aware of the omission, the following penalties for non-compliance with pre-merger approval and post-merger notification requirements apply.

• Failure to submit a post-merger notification is subject to an administrative fine of up to THB200,000, in addition to a daily fine of up to THB10,000 for the duration of the non-compliance.
• Failure to secure pre-merger approval as required is subject to an administrative fine of up to 0.5% of the transaction value of the merger.
• If the violation is perpetrated by a legal entity, and if the offence occurs at the direction or oversight of a director, manager or responsible party, or if such an individual fails to fulfil their responsibilities, the relevant individual is also subject to the penalties applicable to the relevant offence.

New Criteria to Identify Business Operators With Dominant Positions

On 16 December 2025, the Thai Royal Gazette published a new criterion for identifying business operators with a dominant position, raising the market share threshold in the second bullet point below from 10% to 20%. Effective as of 17 December 2025, a merger will require pre-merger approval if it meets one of the following criteria.

• A business operator was engaged in the market for a specific product or service, and possessed a market share of 50% or more in that market, during the previous year (ie, from 1 January to 31 December 2025, if the transaction will occur in 2026), and achieved sales revenue of THB1 billion or more during the same timeframe.
• A business operator ranks among the top three business operators that possessed a combined market share of 75% or more in the market for a specific product or service during the preceding year. However, the criteria for identifying the top three business operators do not apply to any business operator that reports sales revenue of less than THB1 billion for the preceding year, or holds a market share below 20% during that year.

Merger Filings From 2024 to2026

In 2024, a total of 21 merger filings were submitted to the Trade Competition Commission of Thailand (TCCT), with a combined transaction value of THB599.71 billion. Among these filings, 20 were categorised as requiring post-merger notifications, which collectively represented a transaction value of THB373.77 billion. The remaining four filings required pre-merger approval, and had a combined transaction value of THB225.94 billion. This distribution indicates that the majority of merger activity in 2024 did not fall within the scope of transactions expected to create dominant market positions or monopolies, as post-merger notifications are typically applicable to transactions that do not meet the thresholds requiring pre-merger review. Nevertheless, the substantial transaction values recorded in both categories highlight a vigorous level of merger activity, with post-merger transactions contributing a larger proportion to the total transaction value.

During 2025, a total of 24 merger filings were submitted to the TCCT, with an aggregate transaction value of THB1.25 trillion, slightly surpassing the total for the previous year. Of these, 20 were post-merger notifications, reflecting a transaction value of THB1.24 trillion. Four required pre-merger approval, with an aggregate a transaction value of THB 10.62 billion. This consistency in the ratio of post-merger notifications to pre-merger approvals could suggest a stable regulatory environment or similar market dynamics year-on-year. However, the slight uptick in total filings may signal increased merger activity, possibly in anticipation of forthcoming regulatory changes or market consolidation trends.

The data highlights the ongoing importance of pre-merger and post-merger procedures under Thai competition law. Given the large transaction values associated with post-merger notifications, a significant portion of market activity is subject to ex post review, suggesting a broader interpretation of market relevance by the Commission for merger filings. In addition, the comparison between the two years emphasises the need for businesses to stay alert to filing requirements as the regulatory landscape changes, including updates to market share thresholds and stricter criteria for merger review.

As of May 2026, no official records or merger filing statistics are available for the current year. However, as far as is known, the numbers of merger filings submitted between January and April 2026 remain consistent with those recorded in the previous year. Ongoing global developments such as the US–Iran conflict may have implications for the global economy, so merger activity may also experience changes.

New Draft Amendment to the TCA

A number of draft amendments to the TCA were proposed in 2024 and 2025. Notably, the draft amendment presented by the People’s Party (“Draft Amendment”) made significant strides, and has progressed to consideration by the House of Representatives. It successfully advanced through the initial phase of adoption in principle, and has entered the second stage of the amendment process, which involves a comprehensive, section-by-section evaluation. Unfortunately, the Cabinet dissolved Parliament on 12 December 2025, which resulted in the lapse of the Draft Amendment. The Draft Amendment was brought back for deliberation by the House of Representatives on 15 May 2026. This action was initiated by the new Cabinet, which submitted a formal request to the House of Representatives to recommence discussions within 60 days of the beginning of the first parliamentary session following the general election. Consequently, it is feasible that the TCA will undergo revisions, which will be enacted in the near future.

The principal substance of the Draft Amendment concerning merger control, which has been adopted by the House of Representatives, is noteworthy.

• The Draft Amendment expands the definitions of “Business Operator” and “Business”. Specifically, it expands the term “Business Operator” to encompass any individual that engages in the operation of a business, and the new definition of “Business” now includes any activity performed, directly or indirectly, for one’s own commercial advantage or for the benefit of others, with the exception of actions expressly specified in ministerial regulations. The definition of Business Operator in the Draft Amendment is broader than that set forth in the TCA, which restricts the definition to a vendor, a producer for sale, an individual who places an order or imports products into Thailand for sale, a buyer for the production or resale of goods, or a service provider engaged in business activities. Consequently, a holding company that was previously excluded from certain provisions of competition law, including the merger filing requirement in the TCA, may fall within this interpretation unless it receives a specific exemption through ministerial regulations.
• Pre-merger approval is mandatory for all merger filings. In Thailand, pre-merger approval from the Commission is currently mandated solely for mergers that have the potential to create a monopoly or result in a dominant market position. This determination is based primarily on established revenue and market share thresholds. The Draft Amendment states that all mergers are required to secure prior approval from the Commission. However, the specifications concerning merger filings and the applicable exceptions remain vague, particularly with regard to foreign-to-foreign mergers. These details are expected to be explained further in upcoming guidelines that will be released by the Commission.
• A method to collect feedback from stakeholders is necessary, considering the potential competitive effects that could result from unilateral actions or collaborations, impacts on economic efficiency, and implications for consumers.
• The application fee for mergers will rise substantially, from THB250,000 under the TCA to THB5 million per submission in the Draft Amendment. This indicates that the merger filing procedure is set to become more intricate and expensive, even for minor transactions that are unlikely to have a significant effect on the market.
• The penalty for failing to obtain a pre-merger approval is payment of a “Phinai Fine” at a rate not exceeding 5% of the transaction value of the business merger. The transition to a Phinai Fine requires the offender to pay a specified monetary penalty. This fine is not considered a criminal punishment, nor does it entail imprisonment or confinement in place of payment. If no administrative penalty is imposed, and no legal action is commenced within five years of the date of the offence, the statute of limitations will lapse.

Digital Market

In 2026, the TCCT recognised the growing importance of the digital market. This acknowledgement addresses global trends and the significant impact of digital platforms on competition in Thailand. By studying how to regulate e-commerce and digital platforms, the TCCT seeks to tackle challenges posed by multi-sided platforms, where market power can concentrate quickly, highlighting the limitations of traditional regulatory methods. On 24 March 2026, the TCCT issued the Guidelines for the Assessment of Unfair Trade Practices and Conduct, in an effort to enhance clarity and oversight in this area.

The announcement has been in effect since 25 May 2026. The focus on multi-sided platform businesses, particularly those involved in the purchase and sale of goods or services, addresses concerns related to potential monopolistic behaviour, reduced competition, and barriers to market entry. The public consultation phase reflects an intent to engage a wide range of stakeholders, which is important for understanding the complexities of digital commerce and ensuring that regulatory measures are effective and proportionate.

In examining and proposing regulations for digital markets, the TCCT’s actionsindicate a proactive approach. However, several key questions remain unanswered, particularly with regard to appropriate consideration of the market definition of business operator within this market context. Market participants are advised to monitor developments, engage in consultations, and prepare for various potential regulatory scenarios. Effective engagement with the TCCT and thorough compliance planning are important for navigating the evolving legal and competitive landscape in Thailand’s digital sector.

Conclusion

In 2026, Thailand’s merger control framework is undergoing substantial reform, with significant implications for market dynamics and legal compliance. The increasing complexity and activity within the market, coupled with anticipated legal modernisation, requires acquirers and their legal counsel to engage with regulatory authorities on a proactive basis and to apply rigorous analysis to relevant business practices. Should the Draft Amendment be enacted, the resulting legal landscape is likely to feature more robust regulatory oversight, enhanced transparency and stronger deterrents to anti-competitive conduct. These developments may have a material effect on the timing of regulatory approvals and the strategic structuring, negotiation and post-merger integration in M&A transactions.