Section 301 adds on top of base duty
Section 301 additional duties are imposed as an extra tariff layer, not as a replacement for the base duty. When a product is subject to a Section 301 action, the additional rate is added to the base rate from the HTS general column. The total duty is the sum of both layers applied to the customs value. This is why the same product can have a duty bill that appears much higher than the base rate alone suggests — the Section 301 additional layer may be significant.
- Section 301 adds to the base duty; it does not reduce or replace it.
- The base duty comes from the product HTS code general column rate.
- The Section 301 additional tariff comes from the applicable 9903 HTS subheading.
- Both layers are applied to the customs value to calculate total duty.
How to determine whether Section 301 applies
Section 301 applies when three conditions are met: (1) the product HTS code is on the applicable USTR Section 301 product list, (2) the country of origin is within the scope of the Section 301 action, and (3) the effective date of the tariff action has passed. Check the product against the current USTR Section 301 product list and notices for the origin. Verify in the USITC HTS Chapter 99 schedule for the applicable additional tariff rate.
- Check the USTR Section 301 product list for the product HTS code and origin.
- Verify the effective date — Section 301 actions have start dates.
- Check the applicable 9903 rate in the USITC HTS Chapter 99.
- Section 301 applicability is estimate-only; verify with official USTR notices.
Why Section 301 stacking matters for cost planning
For ecommerce sellers and importers, understanding that Section 301 stacks on base duty is essential for landed cost planning. A product with a 2.5% base duty and a 25% Section 301 additional tariff does not cost 2.5% in duty — it costs 27.5% on the customs value. This difference can significantly affect product margins, pricing, and supplier selection decisions. Always calculate both layers before quoting a landed cost to a customer.
- Landed cost must include base duty plus Section 301 additional tariff.
- Section 301 rates can change; estimates based on past rates may be incorrect.
- Different products have different Section 301 rates depending on HTS code and origin.
- Tariff stacking affects supplier selection and product margin calculations.
How to verify the Section 301 rate
To verify the current Section 301 rate: (1) Go to the USITC HTS database and look up the product HTS code. (2) Find the Chapter 99 additional tariff subheading (9903.) that corresponds to the Section 301 action. (3) Read the rate listed for the applicable origin. (4) Cross-reference with the USTR Federal Register notices for the specific tariff action. The USITC HTS is the official tariff schedule; USTR notices provide the policy context and product list scope.
- USITC HTS at hts.usitc.gov — official tariff rate schedule.
- USTR website — Section 301 product lists and notices.
- Federal Register — official publication of tariff actions and amendments.
- CBP CSMS messages — current tariff alert notices.
What Section 301 does not do
Section 301 additional duties do not guarantee that the total duty is a fixed amount. The Section 301 rate is an additional percentage applied to the customs value. The actual Section 301 cost depends on the declared customs value. Section 301 also does not override base duty — it adds to it. Section 301 does not apply to all products or all origins; verification is required.
- Section 301 is an additional rate applied to customs value, not a fixed dollar amount.
- Section 301 does not replace the base duty rate.
- Section 301 applies only when the product and origin are within scope.
- Section 301 rates change; always verify the current rate before filing.
Source note
Section 301 actions are published by the USTR on ustr.gov and in the Federal Register. The USITC HTS database at hts.usitc.gov is the official US tariff schedule. TariffCatalog estimates are preparation aids only; they do not substitute for official tariff verification. Consult a licensed customs broker before filing.