9903.88.03 Explained: Section 301 China List 4, 25% Duty Rate

Key Points

• HTS code 9903.88.03 adds 25% on top of the normal column 1 duty rate for covered China-origin goods, as defined in U.S. notes 20(e) and 20(f) to Chapter 99.
• The additional rate is stated in the HTSUS general column as "the duty provided in the applicable subheading + 25%", meaning the 25% stacks on whatever the base rate already is.
• Nineteen exclusion headings are carved out of 9903.88.03 by its own heading text; if your goods fall under any of those headings, this code does not apply.
• Country of origin is determinative: only articles that are a product of China are subject to this code.
• Confirm current product coverage and any active exclusions against the live HTSUS and with your broker, because the exclusion landscape under 9903.88 has changed repeatedly.

On this page

1. What 9903.88.03 is and which program created it
2. Exact rate and how it appears on an entry
3. Product and country scope: U.S. notes 20(e) and 20(f)
4. The nineteen exclusion headings carved out of 9903.88.03
5. How 9903.88.03 stacks with other duties
6. What importers should do
7. Key references

HTS code 9903.88.03 is a Section 301 Chapter 99 tariff code that imposes an additional 25% duty on Chinese-origin goods whose subheadings are listed in U.S. note 20(f) to Chapter 99 and whose product scope is defined in U.S. note 20(e). Importers and brokers must add this code as a second line on every covered entry, and must pay both the base duty and the additional 25% to CBP at time of entry. The links in this article go to the primary documents: the proclamations, Federal Register notices, and official tariff schedule pages themselves. Read the source.

The facts in this article reflect the HTSUS as of October 10, 2026.

What 9903.88.03 is and which program created it

9903.88.03 is one of several Chapter 99 provisions created under the Section 301 trade action against China. Section 301 of the Trade Act of 1974 authorizes the U.S. Trade Representative to impose duties, fees, or other import restrictions in response to foreign trade practices found to be unreasonable or discriminatory. The broader 9903.88 family of codes covers multiple "lists" of Chinese goods subject to additional tariffs at various rates. Codes 9903.88.01 and 9903.88.02 cover earlier lists at 25%; 9903.88.03 covers a separate tranche of goods also at 25%.

For background on adjacent Section 301 codes, see our articles on 9903.88.01 and 9903.88.02.

The official Harmonized Tariff Schedule at hts.usitc.gov is the authoritative source for the current heading text, the enumerated subheadings in U.S. note 20(f), and the full exclusion landscape under 9903.88.

Exact rate and how it appears on an entry

The HTSUS general column rate for 9903.88.03 reads: the duty provided in the applicable subheading + 25%. That means the 25% is additive, not a replacement. If the base (chapter 1-97) subheading carries a 3.5% general rate, the total duty owed is 3.5% plus 25%, or 28.5% ad valorem. If the base rate is duty-free, the importer still owes the full 25% additional duty.

How the code appears on a CBP entry

9903.88.03 is a Chapter 99 "overlay" code. It rides alongside, not instead of, the regular chapter 1-97 classification. On a standard entry summary, an importer will see two tariff lines for the same shipment:

• Line 1: the chapter 1-97 subheading with its normal general rate
• Line 2: 9903.88.03 with the 25% additional duty

Both lines reference the same entered value and quantity. CBP collects duties on both lines simultaneously. For questions about entry structure and timing, see our article on customs entry filing deadlines.

Product and country scope: U.S. notes 20(e) and 20(f)

The heading text of 9903.88.03 limits applicability to "articles the product of China, as provided for in U.S. note 20(e) to this subchapter and as provided for in the subheadings enumerated in U.S. note 20(f)." Both prongs must be satisfied:

U.S. note 20(e): product-of-China requirement

U.S. note 20(e) defines what it means for an article to be a "product of China" for Section 301 purposes. Country of origin is determined under the standard CBP rules (substantial transformation). Simply transshipping goods through a third country does not change Chinese origin. Verify origin documentation carefully, because CBP actively scrutinizes origin claims on Section 301 merchandise.

U.S. note 20(f): the enumerated subheading list

U.S. note 20(f) is a specific list of chapter 1-97 subheadings whose goods are covered by 9903.88.03. The list is long and has been amended over time. Confirm that your product's 10-digit subheading appears in the current version of note 20(f) in the live HTSUS before concluding that 9903.88.03 applies. If your subheading is not in note 20(f), 9903.88.03 does not apply regardless of origin.

The nineteen exclusion headings carved out of 9903.88.03

The heading text of 9903.88.03 opens with "Except as provided in" and then names nineteen specific Chapter 99 headings. If your goods are covered by any of those headings, they are excluded from 9903.88.03. The excluded headings are:

• 9903.88.13
• 9903.88.18
• 9903.88.33
• 9903.88.34
• 9903.88.35
• 9903.88.36
• 9903.88.37
• 9903.88.38
• 9903.88.40
• 9903.88.41
• 9903.88.43
• 9903.88.45
• 9903.88.46
• 9903.88.48
• 9903.88.56
• 9903.88.64
• 9903.88.66
• 9903.88.67
• 9903.88.68
• 9903.88.69

Each of these exclusion headings has its own scope, typically tied to USTR-granted product exclusions or sector-specific relief. If you believe your product qualifies under one of these exclusion headings, verify the current scope of that heading in the HTSUS and confirm with your licensed customs broker. Do not claim an exclusion heading on an entry without positive confirmation that your specific subheading and product description are covered.

How 9903.88.03 stacks with other duties

Section 301 duties stack on top of all other applicable duties. Common stacking scenarios for Chinese-origin goods include:

• Antidumping and countervailing duties (AD/CVD): If your subheading is subject to an AD/CVD order, those rates apply in addition to the base duty and the 25% Section 301 additional duty. All three are collected at entry.
• Section 232 duties: For goods also subject to Section 232 measures (for example steel or aluminum derivatives), both the Section 232 additional duty and the 9903.88.03 additional duty apply simultaneously on top of the base rate. See our article on 9903.08.22 UAS 232 stacking for an example of how multiple Chapter 99 overlays interact.
• Merchandise processing fee (MPF) and harbor maintenance fee (HMF): These fees apply to the entered value independent of the additional duty and are not waived by 9903.88.03.

Total landed duty burden on some China-origin goods can therefore be substantial. Accurate cost modeling requires pulling all applicable Chapter 99 codes, any AD/CVD case rates, and the base general rate together. Online calculators often miss one or more layers; see our note on why tariff calculators give different answers.

For importers using foreign trade zones to manage duty timing and liability, see our article on FTZ weekly entry procedures.

What importers should do

• Confirm that your product's 10-digit HTSUS subheading appears in U.S. note 20(f) in the current live HTSUS before reporting 9903.88.03 on an entry, and verify country of origin documentation satisfies the U.S. note 20(e) standard.
• Check each of the nineteen exclusion headings listed in the 9903.88.03 heading text to determine whether an active exclusion covers your specific product, and work with your broker to claim the correct exclusion heading if one applies.
• Model the full duty stack, including base rate, 25% Section 301 additional duty, and any applicable AD/CVD or Section 232 rates, before finalizing landed cost estimates and pricing decisions.
• Set up alerts for changes to U.S. note 20(f) and to the exclusion headings, since amendments to the Section 301 lists and exclusions have been frequent; our article on getting tariff change alerts for your specific products explains how to filter notifications efficiently.

Key references

• HTSUS online edition, USITC: the authoritative source for heading 9903.88.03, U.S. notes 20(e) and 20(f), and all exclusion headings under 9903.88.
• Federal Register, Office of the U.S. Trade Representative: Section 301 Federal Register notices establishing and amending the China tariff lists and exclusions.
• CBP Entry Summary guidance: CBP guidance on how Chapter 99 additional duty codes appear on entry summaries.
• CBP CSMS messages: Cargo Systems Messaging Service notices on Section 301 implementation and collection instructions.
• 19 U.S.C. 2411, Cornell LII: the statutory authority for Section 301 trade actions.
• CustomsGenius 2026 tariff code overview: summary of major Chapter 99 codes active in 2026.