Duty vs Tariff vs Tax: What's the Difference?

Your importer has read that goods from China carry a 25% tariff. When their entry shows duty at 28.9%, they email you to ask what the extra 3.9% is for and whether someone got it wrong.

To answer that, you have to separate three terms: tariff, duty and tax. A tariff is the rate the US sets for a product from a given country. A duty is the amount owed on a shipment after every applicable rate is applied. Tariffs and duties are both taxes on imports, and the Constitution lists duties among the taxes Congress has the power to lay.

This guide explains the difference in terms you can pass on to an importer. It then walks through how the duty on a US import is calculated, and why a wrong amount usually traces back to the shipment documents.

Duty vs tariff vs tax: A quick comparison table

What is a tariff

A tariff is a rate, not an amount. It sits in the Harmonized Tariff Schedule of the United States and is keyed to two things: the HTS code of the goods and the country of origin. The same product from two origins can carry two different rates.

Congress sets tariffs. The president adds layers under delegated authority such as Section 301, Section 232 and IEEPA. CBP sets none of them. It collects the duty the rate produces.

That is why the rate moves faster than the schedule around it. The USITC published 32 revisions to the HTS in 2025 and 19 more by 15 September 2026, most of them driven by proclamations and Section 301 notices.

Types of tariff

Three structures appear in the schedule:

• Ad valorem: a percentage of customs value, such as 6.5%.

• Specific: a fixed charge per unit, such as 4.4 cents per kilogram.

• Compound: both applied to the same line.

By purpose, a protective tariff shields domestic producers. A revenue tariff raises money for the government.

The structure decides how predictable your cost is. An ad valorem rate moves with invoice value. A specific rate does not, so a lower unit price raises the effective rate you pay.

What is a duty

A duty is the amount. Apply the rate to one shipment and the figure you get is the duty owed on it.

CBP collects it as a condition of entry, not after the fact. Where cargo is released before the entry summary is filed, 19 CFR 141.101 requires the deposit when that entry summary is filed. CBP allows 10 working days from release for both. What you deposit is an estimate. The final amount is fixed at liquidation.

On the paperwork, one word covers every layer. CBP Form 7501 asks for duty, and that figure holds the base HTSUS rate plus any Section 301, Section 232 or reciprocal layer sitting on the line. The entry summary does not separate them by authority. The importer of record owes the total.

Types of duty

Import duties under the HTSUS. The base rate for the HTS code and origin, plus whatever policy layers apply to it. This is what most brokers mean by duty.

Excise duties. Charged on goods such as alcohol, tobacco and fuel under the Internal Revenue Code, not the tariff schedule. CBP collects the federal excise tax on imported spirits, wine and beer at entry, alongside the duty. It is calculated on volume or proof gallons, not customs value.

AD/CVD. Neither a base rate nor a policy tariff. Commerce sets the margin, the ITC finds injury, and CBP collects a cash deposit at the producer-specific rate. That rate is revisited at administrative review, so the deposit is not the final liability.

Export duties. Not a category in US trade. Article I, Section 9 of the Constitution prohibits taxing exports, so every duty an entry writer handles is an import duty.

How are duties and tariffs calculated? (With examples)

If an entry has ever come back over the duty owed, the problem was rarely the calculation. The amount is built in four steps, and each step depends on a document someone else prepared.

Step 1: Classify the goods: The HTS code comes from the product description on the commercial invoice. That code sets the base rate and determines which Chapter 99 layers can attach to the line.

Step 2: Determine the customs value: Start with transaction value, the price actually paid or payable under 19 U.S.C. 1401a. Then add the statutory additions in 19 CFR 152.103: packing costs, selling commissions, assists, royalties and resale proceeds. These rarely appear on the invoice. They sit in the purchase order or the royalty contract, so someone has to ask the importer for them.

Step 3: Apply the base rate: The rate depends on the code and the origin together. Origin comes off the certificate of origin and needs to agree with the invoice and the bill of lading. A valid FTA claim moves the line to the special rate.

Step 4: Stack the applicable layers: Add the Chapter 99 headings that apply to that code and that origin. Section 232 lines also need the metal content value from a mill certificate.

Example

Take a 38-piece tool set from China under 8466.10.0175, on a shipment worth $40,000. The base HTSUS rate is 3.9%, which comes to $1,560, and Section 301 adds 25% under U.S. Note 20, another $10,000. CBP ruling N354150 states both rates. The entry writer declares $11,560, an effective rate of 28.9%.

What separates $1,560 from $11,560 is one Chapter 99 heading on the line. Miss it and the importer has underpaid by $10,000 on a single product. A China entry this year can carry more layers than these two, so check the current headings before you file.

An entry writer can follow all four steps correctly and still declare the wrong amount, because the documents feeding those steps were never prepared with the entry in mind.

Why duty and tariff calculations go wrong

1. Product descriptions are too vague to classify

19 CFR 141.86 requires the invoice to carry a detailed description of each item, including the name it is known by and its grade or quality. In practice, many invoices describe the goods in three or four words, such as steel fittings, cotton garments or electronic parts.

Those descriptions cannot support a ten-digit classification. Steel fittings could be threaded or welded, and that split changes the base rate. Cotton garments need the construction and the gender before anyone can reach a subheading.

The entry then stops while someone emails the importer, who emails the supplier, and the file waits for a specification to come back. Nobody was unsure about how to classify the product, so the delay came entirely from what the document failed to say.

2. Origin is stated differently across documents

Origin means where the goods were made. 19 CFR 134.1(b) defines it as the country of manufacture, production or growth.

The people preparing the documents often do not know that. A trading company sells goods it did not make. A freight forwarder issues a bill of lading from the port the container left. Each fills in the country it can see, so the invoice, the bill of lading and the certificate can name three different places.

The entry writer then has to work out which of them describes manufacture. Nothing in the file says that outright, so it usually takes an email to the importer and another to the supplier. Origin is also one of the data elements on the Importer Security Filing, which the importer lodges before the container is loaded.

3. Customs value is missing dutiable additions

Duty is charged on customs value, not the invoice total. The invoice price is the starting point. To that, 19 CFR 152.103 requires the importer to add packing costs, selling commissions, assists, royalties and any resale proceeds paid back to the seller.

None of these are part of the sale, so none of them show on the invoice. An assist is a mould the importer gave the factory for free. A royalty is paid separately, often to another company.

The invoice can be right and the value is still short. The entry writer cannot see what is missing, because the documents that prove it never travel with the shipment.

4. Entry writers key the same data by hand

Everything above still has to be typed into the filing software, one line at a time. A large invoice can run to hundreds of lines, and the tariff layers split many of those lines in two.

"I've got 10 people on computers that are working on 4, 5, 600-line items, it takes 2 to 3 days sometimes."
— customs broker, Docxster demo call

The same broker said an 800-line invoice turns into 1,600 lines once the breakouts are applied. When an entry transmits with an error, it comes back as a kickback and his team keys the corrections all over again.

At that volume, a wrong description or a wrong origin gets copied forward before anyone has a chance to question it.

How document automation prevents duty calculation errors

1. Extracting entry data from any document format

Invoices, packing lists and bills of lading arrive as PDFs, scans, photos and handwritten notes, and every shipper formats them differently. Tools that rely on a template for each layout break as soon as one of those shippers changes its invoice, which is why extraction usually stalls at intake rather than at the point of filing.

Docxster reads the document without a template. It identifies the fields the duty calculation depends on, including the product description, value, currency and country of origin, wherever they appear on the page. Because the layout does not have to be known in advance, a new shipper does not require new setup work before their first entry can be processed.

2. Assigning the HTS code from the product details

The first section of this article showed what a vague description does to an entry, and this is where the workflow deals with it. Docxster reads the line item and derives the HTS code from the product details already in the document, so codes arrive with the extracted data rather than being looked up line by line.

The useful part is what happens when the description will not support a code. Instead of assigning something close enough, the system marks the line as incomplete and states what it needs to classify it, such as the material, the construction or the intended use. That request goes back to the shipper as an email, and the answer returns against the same entry.

Brokers with repeat customers can also load their existing parts library, so known items classify against codes the broker has already approved and only new items reach a reviewer.

3. Reconciling origin and value across documents

Brokers already do this check. Someone opens the invoice, the packing list, the bill of lading and the certificate of origin, and confirms the countries and totals agree before the entry is transmitted. It takes a few minutes on a short file and much longer on a file with hundreds of lines.

In Docxster, each item on that checklist becomes a rule:

• The country of origin on the invoice is compared with the certificate of origin

• A port name is mapped to its country first, so Antwerp is read as Belgium

• Totals, weights and quantities are compared across the documents that state them

When two documents disagree, the entry pauses and both values are shown together. You can send the importer an automated request for a corrected document, or route the file to a reviewer. Either way the conflict is settled before the tariff layers go on, not after CBP sends the entry back.

4. Asking the importer for costs the invoice leaves out

Nothing on a commercial invoice tells you that an assist, a royalty or a selling commission applies. You find out only when you ask the importer, and most brokers ask after something on the file already looks wrong.

Docxster sends the importer a form as soon as the shipment documents arrive. The form asks for the costs that entry depends on. A steel or aluminium line needs the mill certificate and the metal content value. A product made with the importer's tooling needs the value of that tooling. A licensed product needs the royalty amount and the contract.

The importer's reply and any files they upload stay attached to the entry. If CBP later questions the customs value, you can show how it was built and what the importer told you at the time.

5. Stacking every tariff layer before the entry is written

Your entry writers now key several rates against one product line. Each extra layer is another Chapter 99 heading your team has to find, check and enter.

"Throw in the IEEPA tariffs, the steel tariffs, the 122 tariffs, and now you've gone from entering one line to entering four or five."
— customs broker, Docxster demo call

Docxster builds this stack after the HTS code and origin are confirmed. It applies the base HTSUS rate first, then adds each Section 301, Section 232 or other Chapter 99 heading the line qualifies for. Your entry writer sees every layer with its rate and amount, with the total owed at the bottom.

Docxster saves each breakdown by product and shipper, so when the same product ships again from the same supplier, the entry starts from a stack your team has already approved.

6. Reviewing entries instead of preparing them

Once extraction, classification, the cross-document checks and the tariff stack have run, your entry writer opens a file that is already filled in. Their job is to check what Docxster has done and approve the entry before it goes to NetCHB or CargoWise.

Docxster also decides which files need a closer look. An entry goes to a reviewer when its classification has low confidence or a value discrepancy is still open. Entries that pass every rule go straight to approval, so your team spends its time on the lines where a decision is needed.

Every approval is logged with the reviewer's name and the time. That log matters because the importer of record carries the liability for what is declared, whoever prepared the entry.

Correct duty depends on the shipment documents

When your importer asks about the extra 3.9%, you can now show them where it comes from. The 25% they read about is the Section 301 tariff, and the 3.9% is the base HTSUS rate for their product. The 28.9% on the entry is the duty those two rates produce on their shipment.

A tariff sets the rate, a duty is what that rate costs on a shipment, and both are taxes on imports. When the duty comes out wrong, the cause is usually a document, such as a vague description, an unconfirmed origin or a cost missing from the invoice.

Docxster checks those documents before your entry writer opens the file, so the classification, origin, value and tariff stack are ready for review. To see how it handles your own shipments, schedule a demo with Docxster.

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