Anti-Dumping Duty on Imports to Thailand: How It Works

Most importers learn the Thai tariff in two layers: the general rate in the customs tariff, and the lower rate available under a free trade agreement when the goods carry a valid certificate of origin. Anti-dumping duty is a third layer that sits outside both. It is not printed as an ordinary rate next to the HS code, it is not reduced by a Form E, and it applies only to particular products from particular countries, sometimes only to particular exporters. Because it is targeted, many importers never meet it. Those who do usually meet it by surprise: the goods were priced on an FTA zero rate, and the duty assessment comes back with an extra line that wipes out the margin.

This guide explains the mechanism rather than any individual case. It covers what anti-dumping duty is and how it differs from customs duty, who investigates and decides in Thailand, how a case moves from petition to final measure, how to check whether your product, origin and exporter are covered, why misclassification and origin claims are where importers get exposed, how the duty shows up in landed cost, and what to put in place with your supplier before you order. We do not quote rates. Measures change through new cases, reviews and expiry, and the only safe source for a current rate is the official notice for that measure, read together with your customs broker. For the wider duty formula, see our guide on how import duty and VAT are calculated in Thailand.

What is an anti-dumping duty, and how is it different from customs duty?

An anti-dumping duty is an additional import duty that a country imposes on a product when an investigation finds the product is being exported to it at less than its normal value and that this is injuring the domestic industry. Normal customs duty, by contrast, applies to every import of an HS code under the general tariff.

The working definition: dumping happens when an exporter sells into Thailand at a price below the normal value of the same product, usually its price in the exporter's home market or a constructed cost-based value. Dumping on its own is not unlawful. A measure is only imposed when three things are shown together: the dumping, material injury (or threat of injury) to Thai producers of the like product, and a causal link between the two. These conditions come from the World Trade Organization Anti-Dumping Agreement, which Thailand applies through its own anti-dumping and countervailing legislation.

The differences from customs duty are practical, not just legal. Customs duty is set by HS code and applies to any origin unless a preference applies. Anti-dumping duty is set by a defined product description and a list of origin countries, and the rate often varies by named producer or exporter, with a separate rate for exporters not individually named. Customs duty is permanent until the tariff changes; an anti-dumping measure runs for a fixed period and can be reviewed, extended or ended. Customs duty can be reduced with a certificate of origin under ACFTA, AFTA or another agreement; anti-dumping duty cannot, because it is a remedy against pricing behaviour, not a tariff concession. And customs duty is a revenue measure, while anti-dumping duty exists to offset a specific pricing practice.

A related tool, the countervailing duty, targets subsidies rather than pricing, and safeguard measures restrict imports regardless of fairness when imports surge. Importers sometimes mix the three up. The checking process in this guide works for all three, but the anti-dumping version is the one most often met on goods sourced from China and other Asian producers.

Who investigates and imposes anti-dumping measures in Thailand?

In Thailand, anti-dumping cases are investigated by the Department of Foreign Trade (DFT) under the Ministry of Commerce, decided by a committee established under the anti-dumping law, and the resulting duty is collected at import by the Thai Customs Department.

It helps to know which office does what, because importers often contact the wrong one. The Department of Foreign Trade runs the trade remedy function: it receives petitions from domestic industry, initiates investigations, sends questionnaires, verifies data, and publishes notices of initiation, preliminary findings, final determinations and reviews. The decision on whether to impose a measure and at what level rests with the committee set up under the law, based on the investigation file. Once a measure is in force, collection is a customs matter: the Thai Customs Department applies the duty on the import declaration for goods within the measure's scope, alongside normal customs duty and VAT.

The legal base is Thailand's anti-dumping and countervailing duty act of B.E. 2542 (1999), with later amendments that added rules against circumvention. You do not need to read the act to import, but two consequences matter. First, the scope of a measure is defined by the notice, not by your supplier's description or by a news article. Second, questions about whether goods are inside the scope, or whether an exporter-specific rate applies, may need input from both sides: DFT for interpretation of the measure, and customs for how it is applied on your entry.

For most small importers the practical channel is the customs broker, who sees the duty assessment on the declaration and can check the measure's notice. A forwarder such as Thai Global Freight (TGF) can coordinate the documents the broker needs, but the duty decision itself belongs to the authorities, and nobody in the logistics chain can negotiate it away. If your product is the subject of an active case, an importer or importer association can also register as an interested party and submit information, which is the only point where commercial arguments are heard.

How does an anti-dumping investigation run from petition to final duty?

A case usually starts with a petition from Thai producers, moves through initiation, questionnaires and verification, may produce provisional measures after a preliminary finding, and ends with a final determination that sets duty rates by exporter for a limited period.

Knowing the sequence tells you when exposure begins, which is earlier than many importers think.

1. Petition. Domestic producers of the like product, or the authority on its own initiative, bring evidence of dumping, injury and a causal link. Petitions must be supported by a sufficient share of domestic production.

2. Initiation. If the evidence is sufficient, DFT publishes a notice naming the product, the HS codes it expects to be involved, the origin countries and the investigation period. This is the moment to pay attention: the notice tells you whether your goods might be caught.

3. Questionnaires. Known exporters, producers and importers receive questionnaires. Exporters who do not respond, or respond inadequately, are typically assessed on the facts available, which tends to produce a higher rate. Importers can submit their own data and views.

4. Verification. Investigators may verify the data supplied, including at exporters' premises.

5. Preliminary determination. If dumping and injury are found on a preliminary basis, provisional measures may apply, usually as a duty or a security collected at import. From this point, goods in scope arriving in Thailand can carry an extra cost even though the case is not finished.

6. Final determination. The committee decides whether to impose definitive duties and at what level, typically with individual rates for cooperating exporters and a residual rate for all others. Price undertakings, where an exporter commits to minimum prices instead of paying duty, are possible under the WTO framework but are not automatic.

7. Duration and review. Under the WTO Anti-Dumping Agreement, measures are generally limited to five years unless a review shows that ending them would lead to continued dumping and injury. Interested parties can request reviews within the life of a measure.

Investigations take months, and provisional duties can land midway through. If you see an initiation notice for your product, reprice forward orders and talk to your supplier before the preliminary stage, not after.

How do you check whether your product, origin and exporter are under a current measure?

Read the official notices for measures and open investigations published by the Department of Foreign Trade, match the product description, origin country and exporter name against your shipment, and have your customs broker confirm how the measure applies on your declaration.

A practical check takes five steps, and it is worth doing at the quotation stage rather than after the goods are on the water.

1. Fix the HS code. Agree the classification with your customs broker first, using the product's material, function and form. Anti-dumping notices list HS codes, so a wrong code at this stage makes the whole check unreliable. Our guide on looking up the Thai customs tariff explains how to read the tariff itself.

2. Search the current measures and investigations. DFT publishes trade remedy information, including lists of measures in force and cases under investigation. Look for your product family, not just your exact code, because a notice may describe the product in words and list several codes.

3. Read the product scope in words. A measure on, for example, a certain type of flat-rolled steel may cover some widths, thicknesses or coatings and exclude others. The description and any exclusions decide coverage. If your product sits at the edge, get a view from your broker in writing, and consider asking DFT directly.

4. Match origin and exporter. Check whether the origin country of your goods is named, and whether your manufacturer or exporter appears with its own rate. If it does not, the residual rate for all other exporters from that country will normally apply. A trading company exporting goods made by a named factory may not automatically carry that factory's rate; the notice will say how producer and exporter combinations are treated.

5. Price it in. Ask your broker to show how the duty will be calculated on your entry and add it to your landed cost before you confirm the order.

Also watch for initiations. A product that is clear today may be under investigation next quarter, and provisional duties can apply to goods already in transit when they arrive.

Why do the exporter name and the true origin matter so much?

Because anti-dumping duty is usually set per producer or exporter and per origin country, the names and origin on your invoice, certificate and bill of lading decide which rate applies, and a mismatch can push you onto the highest rate.

Many importers think of duty as a property of the product. Under an anti-dumping measure it is also a property of who made it, who sold it for export and where it was made. A cooperating exporter that took part in the investigation may have its own, lower rate; a newcomer or a trading company may fall under the residual rate. That means the documents carry real money.

Three practical consequences follow. First, the commercial invoice, packing list and any certificate of origin must name the actual manufacturer and exporter consistently. If your supplier swaps the exporter to a sister company or an export agent, you may lose a company-specific rate you priced on. This is common with smaller Chinese suppliers who export through another company's credentials. Second, the origin must be the real place of manufacture. Shipping from a third country, or through a Thai free zone, does not change origin. Third, if your supplier claims a company-specific rate, ask for evidence that the producer and exporter combination matches the one named in the notice, and keep it on file.

Origin certificates deserve special mention. A Form E under the ASEAN-China agreement proves Chinese origin for tariff preference. In an anti-dumping context it can work against you, because it confirms the origin that the measure targets. That is not a reason to omit it; it is a reason to understand that preference and remedy are separate calculations. The FTA certificate may still reduce normal duty to zero while the anti-dumping duty applies in full. Our guide to types of certificate of origin explains the forms themselves.

Finally, keep records. If customs later questions the rate applied, your file of supplier declarations, production evidence and correspondence is what supports the entry.

How do misclassification and origin claims expose an importer to anti-dumping duty?

If goods within a measure are declared under a different HS code or a different origin, the anti-dumping duty is still owed, and customs can recover it later with penalties; anti-circumvention rules can also extend a measure to goods routed through third countries or lightly processed to avoid it.

This is where most real exposure comes from, and it is rarely deliberate on the importer's side. A supplier suggests a neighbouring code that happens to sit outside the measure's list. A product is described loosely on the invoice. Goods are shipped from Vietnam or Malaysia and the importer assumes that is their origin. In each case the entry may clear on the day, but the duty liability has not gone away.

Three mechanisms catch these entries. The first is the product scope itself. Because a measure is defined by its description, goods that fit the description are covered even if declared under another code. The second is post-clearance audit: Thai Customs can review entries after release and assess unpaid duty, with penalties and surcharges under the Customs Act B.E. 2560 (2017). Our guide to post-clearance audit in Thailand explains how that review works. The third is anti-circumvention. Thailand amended its anti-dumping law to allow measures to be extended where exporters try to avoid them, for example by routing goods through another country, assembling or completing goods from parts in a third country or in Thailand, or making minor changes to the product. If a circumvention investigation succeeds, the duty can be extended to those goods.

For the importer, the defence is simple and unglamorous. Classify on facts, not on supplier advice. Treat any suggestion to change the code, the origin or the exporter name to avoid a measure as a red flag, not a saving. If goods come from a third country, ask what processing actually happened there and whether it confers origin under the relevant rules. And when in doubt, an advance ruling on classification from Thai Customs gives you a documented position before you import; see our guide on customs advance rulings.

It is also worth remembering that misdeclaration to avoid duty can be treated as a customs offence, not just an underpayment. The cost of getting it wrong is usually far higher than the duty itself.

How does anti-dumping duty show up in landed cost and on the declaration?

Anti-dumping duty appears as a separate duty line on the import declaration, assessed on the basis the measure specifies, and it adds to the cost before VAT; ask your customs broker to show the full calculation on a sample entry before you price the goods.

The structure is straightforward even though the rates are not. Your landed cost for goods in scope has these layers: the purchase price and freight to Thailand, insurance, normal customs duty under the general or FTA rate, anti-dumping duty under the measure, VAT at import, and then clearance, port and delivery charges. The measure notice states how the anti-dumping duty is calculated, commonly as a percentage of the customs value for each exporter, and sometimes in another form.

Two points trip importers up. First, the FTA rate and the anti-dumping duty are calculated independently. Using a Form E may reduce normal duty but does not reduce the anti-dumping line. Second, the VAT base at import generally includes duties paid, so an additional duty layer can also raise the VAT amount. Whether and how the anti-dumping duty enters the VAT base for your entry is a calculation your broker should confirm, because it affects cash flow even if you can later claim input VAT.

Price the duty into the deal, not just the budget. If you sell to Thai customers on fixed prices, a new provisional duty can turn profitable contracts into losses. Contract clauses that allocate the risk of new trade remedy measures between buyer and seller, or that let you reprice when a measure is imposed, are worth discussing with your supplier and your own customers. For the cost model as a whole, see our guide to landed cost.

If a measure is imposed and you believe it was applied wrongly on an entry, for example the wrong exporter rate or a product outside scope, raise it promptly through your broker. Correcting an entry or seeking a refund of an amount paid in error follows customs procedures and time limits, which our guides on correcting a declaration and on import duty refunds describe.

What should importers sourcing from China do before ordering goods that are often targeted?

Identify whether your product family has a history of trade remedy cases, check the current notices, confirm manufacturer and exporter identity in writing, and put trade remedy risk into the purchase contract before you pay a deposit.

News and trade-remedy reports show that steel products feature heavily in Thai cases, alongside other industrial materials. Chinese-language importer guides also warn about steel, ceramics, polyester and other industrial inputs from China. Treat that as a reason to check, not as a list: any product with Thai domestic producers who face import competition can be the subject of a petition.

Before placing an order for goods in a sensitive family, work through these steps:

1. Ask the supplier directly whether the product, from their factory, is subject to any anti-dumping, countervailing or safeguard measure in Thailand or is under investigation. A supplier who exports to Thailand regularly should know.

2. Obtain the full legal name and address of the manufacturer and of the exporting entity, and confirm they will appear consistently on the invoice, packing list, bill of lading and certificate of origin.

3. Check the DFT notices yourself or through your broker, as described above, and keep a dated record of the check.

4. Write the classification and origin into the purchase order specification, so the supplier cannot change them without your agreement.

5. Add a clause on trade remedies: who bears duty introduced after the order date, whether you can cancel or reprice, and the supplier's obligation to notify you of any investigation they are party to.

6. Plan for timing. If an initiation notice exists, consider whether to bring shipments forward, hold them, or source the product elsewhere until the outcome is clear.

If you are new to buying from China, our guides on choosing between a trading company and a factory, and on verifying a Form E, help you confirm who you are really dealing with. Those same checks protect you against anti-dumping surprises.

What can an importer do when a new measure, review or expiry affects its goods?

Register as an interested party in an active case if your business is affected, follow review and expiry notices, adjust contracts and timing, and have your broker apply any change on the correct date.

Importers are not only on the receiving end of anti-dumping measures. In an investigation, importers and their associations are interested parties: they can submit questionnaire responses, provide information on how the product is used, argue for product exclusions, and comment on whether duties would harm downstream Thai users. Industrial users who depend on an imported input, for example a fabricator using a particular grade of steel not made in Thailand, are often the most persuasive voices on scope. Taking part requires meeting the deadlines in the notice, and many importers use a trade lawyer for it.

Reviews matter just as much. Measures can be reviewed during their life, for example where circumstances change, and before expiry when the authority considers whether to continue them. A review can change rates, add or remove exporters, or end the measure. If you import affected goods, track the review notices so that you are not still pricing on old assumptions after a change.

When a measure starts, ends or changes, the effective date matters for each shipment. Your broker needs the notice so the correct treatment is applied on the right entries, and you should keep the notices with your import records. Where an importer believes a measure was misapplied, the route is through customs procedures for correcting entries and claiming refunds, or through the review process for the measure itself, not through negotiation with port staff.

Finally, remember the scale of the topic. Most products imported into Thailand are not subject to any anti-dumping measure. The point of this guide is not to make every shipment feel risky, but to make sure that for the product families where measures do exist, the check happens before the order and not after the duty assessment. A forwarder such as Thai Global Freight (TGF) can line up the documents and broker review, but the measure itself is always read from the official notice.