You are using an outdated browser and your browsing experience will not be optimal. Please update to the latest version of Microsoft Edge, Google Chrome or Mozilla Firefox. Install Microsoft Edge

June 2, 2023

Customs Post-assessment Dispute Mechanisms: Challenging Official Duty Assessments

Efficiency and predictability in the global supply chain are critical for business operations. Whether involved in manufacturing, distribution, logistics, or even in the provision of services, most business operators rely upon problem-free customs clearance in the countries in which they operate. If customs disputes do arise and are not effectively addressed, they can have a profound impact on operations, delaying delivery, creating potential civil and criminal liabilities, or even resulting in the seizure of imported goods.

Often, importers or their agents can become complacent, particularly where there has been a period of months or even years of customs clearance without encountering any issues. However, disputes can arise, often relating to origin of goods, classification, and duty assessment. When not addressed early in the dispute process or through settlement, a dispute can escalate, leading to issuance of official letters of assessment by customs authorities. Once Thai customs has issued such a formal letter of assessment to an importer, discretion in settlement is gone and only the full value of the duty assessment can be accepted. At this stage, the only legal avenue for challenge is to accept the duty assessment or to litigate. This article addresses post-assessment litigation options to challenge official customs duty assessments.

Customs Board of Appeals

Once an official assessment is made, an importer has the right to seek a formal appeal of the customs assessment with the Customs Board of Appeals or to otherwise make payment of the full assessment within 30 days of the date it received the assessment. Extensions of time are not permitted. With few exceptions, the right to appeal does not allow the importer to defer an assessed duty payment. This means that the importer must post security for the assessed duty at the time of filing the appeal.

This essentially means that an importer has a tight timeframe in which to prepare and file an appeal and security. Since many customs disputes involve complex issues of goods classification, application of rules of origin, and exemptions under free trade agreements, it is imperative the importers and counsel work in advance of formal assessment so that they are prepared to file appeals within the 30 day period.

The Thai Customs Act provides that the Board of Appeals has 180 days to complete the appellate procedure. The Board of Appeals has the opportunity to extend the procedure for up to 90 days, but only if there is necessary cause. Thereafter, if the appellate procedure cannot be completed within the original or extended time period, an importer has the right to consider withdrawing the appeal and filing a lawsuit in the applicable court.

The Board of Appeals and its Appeal Committee have the right to appoint a subcommittee to perform any entrusted duty. The committee or subcommittee can issue a summons to the appellant or request any person to give an oral statement or submit any documentation concerning the appeal. A Customs Board of Appeals ruling is final, made in writing, and submitted to the appellant. If the appellant is dissatisfied with the ruling, it has the right to file a lawsuit in court within thirty days of receiving the ruling.

Filing Claims with the Court

Where there has been an official duty assessment by Thai customs, an importer, if it wishes to bypass the Customs Board of Appeals process, has the right to file a direct claim with the court of jurisdiction for a customs dispute. This is typically the specialized Tax Court. Alternatively, an importer can await the conclusion of the Customs Board of Appeals process before exercising its right to file a claim with the applicable court. This is a decision that each importer needs to consider on its own, but in most cases the initial decision will be to file appeals with the Board of Appeals as a first dispute resolution option, and only if the ruling is unfavorable will a party then consider further filings to the court. This is a decision made on a case-by-case basis and there is no set formula on what strategy to employ, but there is a general understanding that the Board of Appeals has more expertise than the courts, particularly in complex customs disputes.

As is the case for Board of Appeals reviews, a post of security for the assessment is required during the trial court process. Court proceedings will proceed until issuance of the court judgment. There is a further right to consider an appeal to the Supreme Court, which under current rules has the right to exercise its discretion on whether to accept the appeal. If the appeal is not accepted, then the court judgment will be final and no further avenues of challenge will be possible.

Conclusion

Customs clearance and valuation are important parts of the global supply chain. In most cases, goods move freely and without negative effects. However, when customs conflicts do arise, it is critical that importers and their counsel act to assess and advocate in defense of claims. Where necessary, a well-planned and thorough defense, whether through the customs appeal process or through the courts, can reduce or otherwise eliminate assessed customs liabilities. In fact, a favorable ruling may even set a standard that reduces the likelihood of similar disputes in the future.

RELATED INSIGHTS​ 

May 8, 2026
The global trade environment for Thai exporters in 2026 has shifted significantly. Recent enforcement developments in both the United States and the European Union show a clear shift in trade policy: regulators are no longer focused solely on tariff levels, but also on whether products genuinely originate where exporters claim they do. Adding to this complexity, the US Supreme Court’s February 2026 decision striking down the use of the International Emergency Economic Powers Act (IEEPA) to impose tariffs has upended the legal basis for a major pillar of US tariff policy, creating significant legal and commercial uncertainty for exporters worldwide, including in Thailand. For Thai companies integrated into regional supply chains, this change carries material implications. Although the IEEPA-based US reciprocal tariffs have been struck down, intensified circumvention enforcement continues under separate legal authorities, and the administration has signaled its intent to reimpose tariffs under alternative statutory frameworks, while EU authorities are using anti-circumvention investigations where trade patterns shift. In both jurisdictions, the decisive issue is whether manufacturing in Thailand constitutes substantial transformation under applicable rules of origin. Such origin determinations increasingly drive duty exposure, audit risk and commercial disputes. In 2026, the ability to defend a product’s Thai origin is not merely a procedural step, it is central to preserving market access in the US and EU. Impact Of US Circumvention Enforcement and an Uncertain Tariff Landscape Following the 2025 Framework for an Agreement on Reciprocal Trade, Thailand saw a shift in its tariff relationship with the US. A substantial range of Thai-origin goods were subject to a 19% reciprocal tariff under the IEEPA. However, the Supreme Court’s ruling invalidating the use of IEEPA for tariffs has removed the legal basis for that rate. The Administration has indicated it intends to pursue replacement tariffs under other statutory authorities,
April 29, 2026
Is arbitration only as good as the arbitrator? Undoubtedly. Choosing an arbitrator is therefore one of the most pivotal decisions a party makes in the arbitration proceedings. In practice in Vietnam, many arbitration proceedings have been significantly prolonged because of multiple unsuccessful appointments arising from conflicts of interest, challenges by the opposing party, or subsequent unavailability. In other cases, additional expenses were incurred where appointed arbitrators were located far from the hearing venue or were unfamiliar with the arbitration language or applicable law. To preempt these issues and secure a more efficient and cost-effective appointment, this article proposes a practical, step-by-step approach to arbitrator selection. Step 1: Know Your Own Case At the outset, it is essential to develop a clear understanding of the dispute by addressing the following key considerations: Nature of the dispute: From which sector does it arise (e.g., construction, international trade, investment, banking and finance, technology, intellectual property)? Value and complexity: Is the dispute high or low in value? Does it involve multiple parties, multiple legal systems, or foreign elements? Is its crux related to multiple legal matters? Existing arbitration agreement: Does the agreement specify the seat, language, and governing law? If not, what would be appropriate considering the parties’ conduct and the applicable arbitration rules? Having clear answers to these questions in mind will help identify, from the outset, the core criteria for selecting an appropriate arbitrator. Step 2: Form Your Candidate Pool Based on the understanding developed in Step 1, a candidate pool should be formed through a structured and careful process: Researching Arbitrator Profiles At the initial stage, comprehensive research should be conducted via reliable sources to ensure both accuracy and diversity of candidates. Official sources, such as lists of arbitrators published by arbitral institutions, most notably the Vietnam International Arbitration Centre
April 9, 2026
In March 2026, the United States Trade Representative (USTR) initiated two significant investigations under Section 301(b) of the Trade Act of 1974 that directly affect Thailand. The first investigation examines overproduction in manufacturing sectors caused by government support or policies that distort normal market conditions across 16 economies, including Thailand. The second investigation, launched the following day, targets 60 economies, also including Thailand, for alleged failures to impose and effectively enforce prohibitions on the importation of goods produced with forced labor. Taken together, these investigations represent a significant escalation in US trade enforcement and create substantial risk for Thai exporters, manufacturers, and businesses with supply chain connections to the United States. The investigations are moving on an accelerated timeline, with the USTR indicating that potential trade measures, including tariffs, could be imposed as early as July 2026. This article provides an overview of the investigations, highlights their specific implications for Thailand, and outlines practical considerations for affected businesses. Section 301 as a Trade Enforcement Tool Section 301 of the Trade Act of 1974 gives the USTR authority to investigate foreign acts, policies, or practices that are considered unreasonable or discriminatory and that burden or restrict US commerce. If the USTR concludes that such practices exist, the statute allows a wide range of remedial measures, including the imposition of tariffs, nontariff trade restrictions, and negotiated agreements with foreign governments. Unlike other trade authorities, Section 301 does not set limits on the level of tariffs or the duration of measures, giving the USTR considerable flexibility to address perceived trade imbalances or unfair practices. Historically, Section 301 investigations take up to a year to complete. In this instance, however, the USTR has indicated that the investigations will proceed on a much faster timetable, with an unofficial target of concluding by July 2026.
April 1, 2026
On March 30, 2026, Thailand’s Customs Department announced a strategy to raise import duties on a broad range of consumer goods—including plastic items and electronics accessories—to their maximum statutory ceilings, which often sit at 30% or 40%. Many of these goods currently benefit from promotional or incentive rates as low as 5%. For importers, e-commerce platforms, and logistics providers, this development demands immediate attention. While these increases generally require cabinet approval, they do not require full parliamentary amendment of the Customs Tariff Decree B.E. 2530, as the Customs director-general and the finance minister hold delegated authority to adjust rates within existing statutory bounds. Businesses should not assume that the legislative process will provide significant lead time before higher rates take effect. Death of the De Minimis: Abolishing the THB 1,500 Loophole This “ceiling-rate” policy, which is designed to equalize the landed cost of foreign goods with the domestic production costs of Thai manufacturers, builds on a sweeping set of customs reforms that have already begun to reshape Thailand’s trade environment. The foundation of this new regime was laid on January 1, 2026, when Thailand formally abolished the longstanding THB 1,500 duty exemption for small imported parcels under Customs Notification No. 219/2568. Every imported item is now subject to VAT and applicable import duties for its declared value, regardless of parcel size or transaction amount. By narrowing the scope of exemptions previously granted to low-value goods under the Customs Tariff Decree B.E. 2530, the government has made clear that the era of tax-free cross-border micro-imports is over. Three-Phased Strategy and Legal Modernization The March 30 announcement is the second phase of a three-part regulatory roadmap: Immediate enforcement: The removal of the THB 1,500 loophole and the imposition of VAT on all parcels, effective January 1, 2026. Tariff realignment: The current