Tariff Stacking Explained: Section 301, 232 and AD/CVD

In 2026, most US imports will pay more than their base rate. Since July 24, a Section 301 duty has applied to goods from 60 economies, which together make up 99.4% of US imports. Depending on the product, the same entry line can also carry China Section 301 list duties, Section 232 duties or AD/CVD.

Adding these duties together is simple, because each rate is applied to the same customs value. The harder part is knowing which duties apply to a line in the first place. Each one depends on the HTS code or the country of origin, and you take both from the shipment documents. So if either field is wrong, the total will be wrong, even when every rate is correct.

This guide walks you through how tariff stacking works, with worked examples for each layer. It also shows you how to confirm the two fields that decide the stack before you file.

What is tariff stacking

Tariff stacking is when more than one tariff applies to the same product under separate legal authorities. Each tariff has its own Chapter 99 number, so one entry line can carry several of them. CBP's July 2026 guidance sets the order for reporting these numbers, starting with Section 301, then Section 122, 232 and 201.

Stacking has become common because several programs now run at once. Section 232 duties of 10% to 50% have applied to certain steel, aluminum and copper articles since April 6, 2026. Since July 24, 2026, a Section 301 duty of 10% or 12.5% also applies to imports from 60 economies, which cover 99.4% of US imports.

As a result, the base rate is rarely the full duty. You pay the base rate plus every layer triggered by the product's HTS code and origin.

The main kinds of tariffs

Here’s a look at the main kinds of tariffs that you may see in the US customs:

1. Column 1 and Column 2 rates of duty

The base rate for every product is listed in the HTSUS. The country of origin decides which column you use. Column 1 General shows the Most Favored Nation (MFN) rate, which applies to goods from most countries. Column 1 Special shows lower or zero rates for goods that qualify under a free trade agreement, such as USMCA. 

Column 2 rates of duty apply to goods from the countries in HTS general note 3(b), which are Belarus, Cuba, North Korea and Russia. This means one HTS code can have three different base rates. The origin shown on the shipment documents decides which rate you apply.

2. Section 301 tariff list

USTR uses Section 301 of the Trade Act of 1974 against trade practices it finds unfair. The best-known Section 301 tariff list covers goods from China. USTR reviewed these duties in 2024 and decided to keep them. It also raised the rates on some products, such as electric vehicles to 100% and semiconductors to 50%. 

A second Section 301 action, on forced labor, took effect on July 24, 2026. Under this action, goods from China pay an additional 12.5%. CBP's Section 301 tariff list PDF for this action shows which HTS codes are covered.

3. Section 232

Section 232 duties apply to specific products, whatever country they come from. Steel, aluminum and copper articles, and products made from them, pay 10% to 50% of their full customs value. Passenger vehicles, their parts and certain semiconductors pay 25%. Products covered by Section 232 are excluded from the forced labor action. This means the HTS code decides which of these two layers applies.

4. Reciprocal tariffs and the forced labor action

The reciprocal tariffs imposed under IEEPA no longer apply. On February 20, 2026, the Supreme Court ruled that IEEPA does not allow the President to impose tariffs. A temporary 10% surcharge under Section 122 applied until July 24, 2026, when the forced labor action took effect. Economies that ban forced labor imports, or have committed to do so, pay 10% under this action. All other covered economies pay 12.5%. For the EU, Japan, South Korea, Switzerland and Taiwan, the rate includes the base rate. For example, a Japanese product pays a total of 12.5%, unless its base rate is already 12.5% or higher.

5. AD/CVD

Antidumping and countervailing duties do not have one fixed rate. The Department of Commerce sets the rate in each case, and it can differ for each producer and exporter. CBP says you must know the exporter and the manufacturer to find the correct case number and rate for the entry summary. This means two shipments with the same HTS code can pay different AD/CVD rates.

How tariff stacking works

The previous section covered each type of duty on its own. This section shows how those duties combine on a single entry, in the order you apply them:

Layer 1: The base rate

Every entry starts with the base rate from the HTSUS. The HTS code decides the rate for the product, while the country of origin decides whether you read it from Column 1 General, Column 1 Special or Column 2. The base rate is part of every entry, even when the rate is free.

Layer 2: Section 301 duties on China

The China Section 301 duties are added when the goods are of Chinese origin and the HTS code appears on one of the Section 301 lists. Both conditions must be met, so a Chinese product that is not on the lists does not carry this layer.

Layer 3: Section 232 duties

Section 232 duties are added based on the product rather than the origin. When the HTS code falls under a Section 232 action, such as steel, aluminum, copper or vehicles, this layer applies to goods from every country.

Layer 4: The forced labor Section 301 duty

The forced labor duty replaced the reciprocal tariffs as the broad duty based on origin. It is added when the goods come from one of the 60 covered economies, as long as the product is not exempt and is not a Section 232 good. Because Section 232 goods are excluded, a product carries either Layer 3 or Layer 4, but never both.

Layer 5: AD/CVD

AD/CVD is added only when an order covers the product from that country. The rate then depends on the producer and the exporter, and CBP confirms that it applies on top of any Section 301 duty.

Tariff stacking examples

To see how these layers work on a real entry, take one product and ship it from two countries. The product has a customs value of $10,000 and a base rate of 5%.

A shipment from China

This product appears on Section 301 List 3, so a shipment from China carries the 25% China duty. The shipment also carries the 12.5% forced labor duty, because USTR applied it to all Chinese products outside the exemption lists. Each rate is applied to the same $10,000. The base rate adds $500, the List 3 duty adds $2,500 and the forced labor duty adds $1,250. The total duty comes to $4,250, or 42.5% of the customs value.

A shipment from Vietnam

When the same product comes from Vietnam, the China Section 301 duty no longer applies. The shipment carries only the 5% base rate and the 12.5% forced labor duty for Vietnam. The total duty comes to $1,750, or 17.5% of the customs value.

Where Section 232 changes the outcome

The outcome changes if the product is a Section 232 steel article. In that case, the forced labor duty does not apply to either shipment. The Section 232 duty applies in its place, so the total depends on the Section 232 rate for that article.

What determines your stack

Now that you have seen the layers at work, it helps to know what triggers them. This section looks at the two fields behind every layer and where you find them:

The HTS code

• The HTS code sets the base rate for the product.

• It decides whether the product falls under a Section 232 action or a China Section 301 list.

• The forced labor exemptions are listed by HTS code, so the code can remove a layer as well as add one.

The country of origin

• The origin decides which HTSUS column applies, including any free trade agreement or Column 2 rate.

• It decides whether the China Section 301 duties apply and which forced labor tier the goods fall into.

• AD/CVD orders are specific to a country, and the rate depends on the producer and the exporter.

Where both fields come from

• CBP requires every commercial invoice to show a detailed description of the goods and their country of origin.

• A free trade agreement claim also needs the origin supported by the certificate of origin.

• If either field is wrong, every layer that depends on it will be wrong too.

How document automation helps tariff stacking

Both fields that decide the stack are fixed long before anyone opens the filing software. Docxster works at that earlier point, between the shipment documents and the system your team files in. The steps below follow the order in which the HTS code and the origin come into the stack.

1. Capturing product details and origin at intake

Shipment documents reach Docxster through your existing inbox or through an upload in Docxster Forms or Chat. Docxster reads invoices, packing lists and certificates of origin in any format, including scans. Each shipper can use its own layout, since no template is set up per shipper. The description and origin for every line land in a table, and any field Docxster is unsure of is sent to a reviewer.

2. Assigning the HTS code and applying the layers

The HTS code sets the base rate and decides whether a Section 232 action or a China Section 301 list applies. A wrong code can therefore add a layer that should not be there or miss one that should. For each line, Docxster proposes an HTSUS code based on the invoice description. 

Each proposal shows how confident the model is and which precedents support it. Items already in your parts library are matched from the library before the AI classifier is used. After your reviewer approves the code, Docxster adds the base rate and every layer that the code and origin call for. 

Complex or contested classifications still need your broker's own legal reasoning, since Docxster does not build a full GRI analysis.

3. Matching origin across the shipment file

The origin decides which base column applies, whether the China Section 301 duties apply and which forced labor tier the goods fall into. If the invoice and the certificate of origin name different countries, the stack can pick up the wrong layers. 

Docxster checks the same fields across the invoice, packing list, bill of lading and certificates, and your team only sees the fields that conflict. You can also add your own validation rules, such as a check that the invoice origin agrees with the certificate of origin on every entry. This way, the origin is settled before any country-based layer is applied.

4. Getting missing origin details from the shipper

Without an origin, you cannot tell which base column, Section 301 duties or forced labor tier apply to a line. The stack stays incomplete until the shipper confirms it. If a line has no origin or an unclear one, Docxster sends the shipper a request through Docxster Forms or Chat. Email is used when those channels are not available. The shipper's answer is captured and added to the entry, so the country-based layers can be applied without a round of follow-up emails.

5. Handing verified data to your filing software

Each Chapter 99 number in the stack has to reach the entry summary with the correct HTS code and origin behind it. Once the code and origin are approved, Docxster sends the data to the filing platform your team already uses. Your entry writer starts from a stack built on checked inputs, rather than rebuilding each layer from the paperwork.

Getting the tariff stack right starts with the documents

Every duty in a tariff stack comes back to two fields on the entry. The HTS code decides the base rate, the Section 232 duty and any China Section 301 list duty. The country of origin decides the column, the forced labor tier and whether an AD/CVD order applies.

Once both fields are correct, the calculation itself is simple. Most problems start earlier, when an invoice description is too vague to classify, or when the invoice and the certificate of origin show different countries.

Docxster reads your shipment documents as they arrive, suggests the HTS code for each line and checks the origin across the whole file. It then applies the duties that the code and origin trigger, before the data reaches your filing software. To see how this works on your own entries, book a demo with Docxster.

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