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

Subscribe to Updates

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 Professionals

Practices

Customs and International Trade

Dispute Resolution and Litigation

Location

RELATED INSIGHTS​ 

August 6, 2026
Every month, VAT-registered businesses in Thailand calculate their output and input VAT and file a return to pay the net amount due or claim a refund. Yet a common and costly dispute arises when a business that has paid input VAT to its supplier—and done everything asked of it—later finds that input VAT rejected on the grounds that the tax invoice was issued by “a person not entitled to issue tax invoices.” In these cases, a buyer may have confirmed the supplier’s VAT registration on the Revenue Department’s website, paid through the banking system, received a complete tax invoice, and kept full payment and inventory records. Even so, if the Revenue Department later determines that the supplier did not genuinely make the sale or collected the VAT without remitting it, the department can disallow the input VAT and assess additional tax, surcharge, and penalty—often more than a year after the transaction. A new article from tax and dispute resolution specialists at Tilleke & Gibbins in Bangkok examines how the Revenue Department and the courts approach these disputes, including two recent Supreme Court (Tax Division) decisions confirming that the taxpayer bears the burden of proving a supplier genuinely sold and delivered the goods and received payment. It considers why the VAT registration system offers no legal safe harbor, why the evidentiary burden falls hardest on online and cross-border transactions where buyers and sellers never meet, and how the Revenue Department’s own digital infrastructure could detect non-remitting suppliers at the source rather than shifting the loss to good-faith buyers. The article also sets out practical guidance: how to build a comprehensive “know-your-supplier” file at the time of a transaction, the procedural steps and strict deadlines for challenging a VAT assessment, and why dispute readiness belongs alongside tax planning at the center
Read More
July 21, 2026
On July 6, 2026, Myanmar’s Ministry of Finance and Revenue introduced revised procedures governing the importation and exportation of goods and vehicles, replacing the framework that had been in place since 2017. The revised procedures were introduced in Notification No. 115/2026, which establishes updated compliance requirements and penalties for importers and exporters, covering licensing, declarations, product specifications, prior arrival of goods, and imports or exports made without the required licenses or permits. Scope Unlike its predecessor (Notification No. 6/2017), which focused primarily on import-related noncompliance, the new notification regulates both import and export activities and introduces a separate penalty schedule for export violations. Exporters are now required to ensure that their exports comply with the approvals stated in export licenses and permits, match the information declared in export declarations, and are supported by the required licenses, permits, and accompanying documents. Import Compliance and Penalties The new notification imposes several compliance requirements on importers. Importers must ensure that the country of origin, branding, labeling, and other product information are consistent with the relevant import license or permit, import declaration, and the imported goods. For vehicles and machinery, the model year must match the year approved by the Ministry of Commerce. Importers must also ensure that goods are not imported before the issuance or after the expiry of the import license or permit, and that the imported quantity does not exceed the approved amount. Failure to comply with these requirements may result in regulatory action. As for the notification’s revised penalties for noncompliance with import licensing requirements, imports made without the required import license, permit, or import declaration may be subject to fines ranging from one to three times the assessable value (AV) of the goods, depending on the category of goods involved. Certain vehicles and machinery, as well as specific
Read More
June 29, 2026
Thailand’s cabinet has approved the draft Act on Liability for Defective Goods, commonly called Thailand’s “Lemon Law.” The Draft Act is currently pending consideration by Parliament. The draft law aims to strengthen buyers’ position in pursuing cases against sellers. While the Civil and Commercial Code offers provisions governing liability for defective goods, it is difficult in practice for buyers to successfully make a claim against sellers, particularly where defects are latent and not discoverable at the time of sale or delivery. By introducing product-specific rules and clearer remedies, the new law is intended to modernize Thailand’s consumer protection framework and align it more closely with international standards, and to help relieve the buyer’s burden of proof against the seller in product liability cases. If enacted, the draft act will take effect 180 days after publication in the Government Gazette, giving businesses a transition period to assess their compliance obligations. This article provides an overview of the key provisions of the draft act and highlights some practical considerations for businesses operating in Thailand. Scope and Key Definitions The draft act applies to sellers—defined as persons who sell goods in the ordinary course of business—and protects buyers, a term defined broadly to include not just the original purchaser but also transferees and successors in title. This expands the class of people who can bring claims. The law does not apply to used goods, live animals, or goods exempted by future ministerial regulation. It also leaves intact any separate warranties, promises, advertisements, or other guarantees a seller has given; those remain enforceable alongside the new statutory rights. General Liability for Defective Goods Sellers are liable for defects that exist at the time of delivery, regardless of whether the seller knew about them. Liability arises where a defect reduces: The benefit intended under
Read More
June 22, 2026
Arbitrator independence and impartiality form the cornerstone of a legitimate arbitral process. Under section 19 of the Thai Arbitration Act B.E. 2545 (2002), prospective arbitrators must disclose circumstances likely to give rise to justifiable doubts as to their impartiality or independence, and existing arbitrators must do so throughout proceedings. This mirrors article 12 of the UNCITRAL Model Law. Yet despite this clear mandate, practical implementation varies significantly across Thailand’s arbitration landscape. Background Thailand’s two principal arbitration institutions, the Thai Arbitration Institute (TAI) and the Thailand Arbitration Center (THAC), both maintain procedures for addressing arbitrator challenges and require compliance with the statutory disclosure obligation. Under both sets of rules, any party wishing to challenge an arbitrator must submit a challenge application within fifteen days of becoming aware of the relevant facts, and a committee is appointed to consider the matter on a case-by-case basis. The TAI additionally prescribes its Code of Ethics and Conduct for Arbitrators to further emphasize the expectation of impartiality and transparency. However, Thailand’s arbitration ecosystem extends well beyond the TAI and THAC. Several sector-specific institutions also administer arbitral proceedings, including the Thai Commercial Arbitration Office under the Board of Trade of Thailand, the Arbitration Centre of the Office of the Insurance Commission, the Arbitration Centre of the Securities and Exchange Commission, the Office for the Prevention and Resolution of Disputes regarding Intellectual Property, and the Arbitration Centre of the Thai General Insurance Association. These institutions each operate under their own procedural rules, which were developed to serve particular industries and dispute profiles. The procedural mechanisms for securing and documenting an independence declaration are not uniformly established across these forums. Consequences of Procedural Inconsistency This creates a notable gap. Not all arbitration bodies have a formalized procedure requiring written independence statements before proceedings commence. Some tribunals proceed
Read More