Effective March 1, 2023, USPS customs forms require the Harmonized Tariff Code (HTC)  be included for everything shipped internationally, except documents. UPS has had this in effect for years.

There are two search tools that we recommend to help determine the proper HTC - The U.S. International Trade Commission HTS search tool and The U.S. Census Bureau search tool. Both of these tools will provide up to a ten-digit Schedule B number (which includes the six-digit HS code). The six-digit HS code is required on the customs form(s). Should the code be more than six digits, you need only include the first six digits.

Click this link to view an informative video, provided by the US Dept. of Commerce International Trade Administration, titled Understanding Your Products HS Code.