Harmonized System 101: An Importer's Guide to HS Codes

Businesses across the world use the Harmonized System (HS) to classify imported goods for easy identification by customs authorities. In the United States, the HS also forms the core of the U.S. Harmonized Tariff Schedule (HTS), which is used by importers and U.S. Customs and Border Protection (CBP) to calculate duties due on imported goods.

What Is the Harmonized System?

The Harmonized System is an internationally recognized method of commodity classification used by most countries to simplify the process of identifying imported goods. It was developed by the World Customs Organization, and uses six-digit codes to describe over 5,000 groups of commodities. 

Many countries, including the United States, use the structure of the HS as the basis for their tariff schedules.

How Is the Harmonized System Structured?

According to the WCO, HS codes are divided into sections, chapters, headings, and subheadings. A simple example of an HS code is 6403.59, which is taken from Section XII of the HS. 

• There are 21 sections in the HS, each containing a grouping of similar items
• The first two digits, 64, represent the HS chapter for footwear, gaiters, and parts of similar articles
• The next two digits, 03, denote footwear with outer soles of rubber, plastics, leather, or composition leather and uppers of leather
• Subheading 59 describes “other footwear”, which is to say footwear not specifically described elsewhere under the heading

The U.S. International Trade Commission (ITC) uses the HS as the foundation for the country’s tariff classification system, the HTS.

What Is the Difference Between an HS Code and an HTS Code?

An HS code is an internationally recognized six-digit number used to identify commodities for the purpose of international trade. HTS codes, on the other hand, are specifically used by importers in the U.S. to identify goods and calculate what duties are due on them once they reach the country.

While all HTS codes contain an HS code as their root, HS codes do not denote duty rates. However, the HS is still a core document U.S. importers need to understand before bringing goods into the country.

Why Does the Harmonized System Matter for U.S. Customs Compliance? 

The HS forms the backbone of the HTS, and understanding the WCO’s General Rules for the Interpretation of the Harmonized System is the first step toward learning how to classify imported goods and estimate duties accurately. As such, the HS matters for purposes of estimating duties and documenting elements of the customs clearance process.

How Do HS Codes Affect Duties, Documentation, and Tariffs? 

HS codes are the basis for calculating duties in the United States since they form the core of the HTS: in this way, they affect duties and documentation. For instance, if an importer purchases goods from an overseas supplier, it’s common for that supplier to include the HS code for those goods to simplify tariff classification for their foreign buyers.

If we refer back to the earlier example of an HS code for a shoe, the HTS code in this case is 6403.59.9030 and carries a most-favored-nation (MFN) duty rate of 10%. The additional subheadings 90 and 30 specify women’s footwear with pigskin uppers. 

The HS code is the starting point for determining duties and is an important data point on commercial invoices and import documents like the Importer Security Filing (ISF).

What Happens If You Use the Wrong HS Code?

Using the wrong HS code is likely to result in misclassification of the affected imported goods. CBP takes preventive measures in ports across the world to ensure misclassified goods are identified and rejected early in the import process. However, even if those goods are accepted initially, misclassification can result in penalties later.

Since the HS informs the HTS, using the wrong HS code will almost certainly result in using the wrong HTS code as well. This will lead to errors on the entry summary (CBP Form 7501) and miscalculated duties.

It’s worth mentioning here that while exporters must provide an accurate description of the goods they sell to importers in the U.S., not all exporters give the HS code for their products to their importers. This doesn’t free the importer from the obligation to provide the correct HTS code on relevant customs documentation. Importers sometimes get penalized by CBP for using the wrong HS code or no HS code at all because they assumed it wasn’t necessary after the supplier failed to supply it.

CBP takes duty payments seriously, and if they find evidence of underpaid duties due to use of the wrong HS/HTS code, they can assess fines along with the balance of unpaid duties up to five years after the shipment is finalized.

How Often Does the Harmonized System Change?

The WCO reviews the HS every five to six years, adding new commodity codes as necessary and resolving HS-related trade disputes in the international trade community.

How Can Importers Stay Current With HS Updates? 

The WCO maintains a newsroom page on its website where importers can stay up-to-date with changes to the Harmonized System and other important developments in international trade. In the U.S., Licensed Customs Brokers keep up with this information to ensure their services comply with the most recent developments in international customs law.

If you have questions about the Harmonized System and its impact on you as a U.S. importer, reach out to our customs experts at (855) 912-0406 or complete our contact form online today.

Sources

What is the Harmonized System (HS)?, World Customs Organization

Harmonized Tariff Schedule, United States International Trade Commission, 2026 Revision 9

General Rules for the Interpretation of the Harmonized System, World Customs Organization