9903.91.02 Explained: Section 301 Four-Year Review, 50% Duty

Key Points

• 9903.91.02 is a Chapter 99 Section 301 four-year-review code that imposed an additional 50% duty on articles the product of China covered by U.S. note 31(c) to Subchapter III of Chapter 99.
• The code became effective for entries on or after September 27, 2024, and covered two specific HTSUS subheadings: 8541.42.00 and 8541.43.00 (certain solar cells and modules).
• Both product-scope windows ran from September 27, 2024 through February 1, 2026, meaning as of the facts date of October 12, 2026, neither subheading remains covered under this code.
• Because both windows have ended, importers with entries during the September 27, 2024 to February 1, 2026 window should confirm duty liability and entry accuracy; no goods are covered under 9903.91.02 today.
• The rate stacks on top of the regular Chapter 1-97 duty: the formula is the duty in the applicable subheading plus 50%.

On this page

1. What 9903.91.02 is and what program created it
2. Exact product and country scope
3. The 50% rate and how it stacks with other duties
4. Effective window and current status
5. How this code appears on a CBP entry
6. What importers should do
7. Key references

9903.91.02 is a Section 301 China tariff code created as part of the four-year statutory review of the original Section 301 action. It imposed an additional 50% duty on two categories of Chinese-origin solar products, effective for entries on or after September 27, 2024. Both covered subheadings had windows that ran from September 27, 2024 through February 1, 2026. As of October 12, 2026, both windows have expired and no goods are currently covered under this code. Importers and brokers should focus on entries made during that window for any compliance review.

The links in this article go to the primary documents: the proclamations, Federal Register notices, and official tariff schedule pages themselves. Read the source.

What 9903.91.02 is and what program created it

Section 301 of the Trade Act of 1974 authorizes the U.S. Trade Representative to impose additional duties on imports from countries engaged in unfair trade practices. The original Section 301 action against China produced four lists of covered goods, each assigned codes in the 9903.88 series. Congress also requires a statutory four-year review of those actions, and that review produced a separate series of escalated rates now coded in the 9903.91 and 9903.92 range of the HTSUS.

9903.91.02 is one of those four-year-review codes. Its official heading text reads: Effective with respect to entries on or after September 27, 2024, articles the product of China, as provided for in subdivision (c) of U.S. note 31 to this subchapter. U.S. note 31(c) defines the exact product coverage for this code. Importers should read that note directly in the current HTSUS at hts.usitc.gov to confirm the full legal text and any annotations.

For context on the broader 9903.91 code family and how the four-year review produced a 25% rate code alongside this 50% code, see our related article 9903.91.01 Explained: Section 301 China Four-Year Review, 25% Duty.

Exact product and country scope

Country scope is simple: 9903.91.02 applies only to articles that are the product of China. No other country is covered.

Product scope is defined by the two subheadings listed in U.S. note 31(c) as associated with this code:

• 8541.42.00, window September 27, 2024 through February 1, 2026
• 8541.43.00, window September 27, 2024 through February 1, 2026

Subheadings 8541.42.00 and 8541.43.00 cover photovoltaic cells, specifically certain solar cells and solar modules. If you are importing Chinese-origin goods classified under either of these subheadings and your entry date fell within the September 27, 2024 to February 1, 2026 window, 9903.91.02 applied to those entries.

As of October 12, 2026, both windows have ended. Neither subheading is currently covered under 9903.91.02. Importers should confirm current classification and applicable Section 301 codes in the HTSUS or with their broker, as other codes in the 9903.88 or 9903.91/.92 series may apply to these goods under separate windows.

The 50% rate and how it stacks with other duties

The HTSUS general column rate for 9903.91.02 is: the duty provided in the applicable subheading + 50%.

That formula means the 50% is additive, not a replacement. On a typical entry, the math works as follows:

• Start with the normal Chapter 84 or Chapter 85 column 1 general rate for the underlying subheading (for example, 8541.42.00 or 8541.43.00).
• Add the 50% Section 301 four-year-review rate from 9903.91.02.
• Add any other applicable Section 301 rates from a 9903.88 series code if that code also covered the same goods during the same period.

Stacking matters. During the covered window, goods under 8541.42.00 or 8541.43.00 may have been subject to both a base 9903.88 series rate and the 9903.91.02 escalation. Confirm the full duty picture for any entry in the window by reviewing which Chapter 99 codes were declared and whether all applicable rates were correctly assessed. For a broader look at how 9903.88 list codes interact with escalation codes, see 9903.88.15 Explained: Section 301 China List 4, 7.5% Duty Rate.

Effective window and current status

9903.91.02 became effective for entries on or after September 27, 2024. The two covered subheadings both ran through February 1, 2026.

As of the facts date of October 12, 2026, both windows have ended. There are currently zero subheadings in force under 9903.91.02. This does not necessarily mean the goods themselves are free of Section 301 duties. It means this specific code is no longer the operative vehicle. Other codes in the Chapter 99 Section 301 framework may still cover 8541.42.00 and 8541.43.00 goods from China. Verify current applicability in the HTSUS.

For entries made during the September 27, 2024 through February 1, 2026 window, the 50% rate was legally in effect and should have been declared. If entries in that window did not include 9903.91.02, that is a potential underpayment. If 9903.91.02 was declared after February 1, 2026, that may be an overpayment. Both scenarios warrant review.

How this code appears on a CBP entry

Chapter 99 codes like 9903.91.02 are not standalone classifications. They ride alongside the regular Chapter 1-97 classification on CBP entry documentation. On a typical entry summary, you will see two lines for the same commercial invoice line:

• The Chapter 85 subheading (for example, 8541.42.00) with its normal rate and dutiable value.
• 9903.91.02 on a separate line, referencing the same value, with a rate of the applicable subheading rate plus 50%.

Both lines must be present for entries within the covered window. The Automated Commercial Environment (ACE) system will calculate and assess the additional duty based on the declared Chapter 99 code. Brokers should confirm that entry software correctly maps 9903.91.02 to entries dated September 27, 2024 through February 1, 2026 only, and does not apply it outside that window.

For guidance on the current HTSUS structure and 2026 code updates, see our 2026 tariff code overview.

What importers should do

• Audit entries in the window. Pull all entry summaries for Chinese-origin goods under 8541.42.00 and 8541.43.00 dated September 27, 2024 through February 1, 2026. Confirm that 9903.91.02 was declared and that the 50% additional duty was correctly assessed on each line.
• Check for stacking errors. Verify that any co-applicable 9903.88 series codes were also declared on those same entries, and that the combined rate was calculated correctly against the correct dutiable value.
• Confirm current coverage separately. Because both windows under 9903.91.02 have ended, check the current HTSUS and any active CBP guidance to identify which Chapter 99 codes, if any, now apply to 8541.42.00 and 8541.43.00 imports from China.
• File corrections as needed. If an audit reveals underpayments or overpayments within the window, work with your broker to file the appropriate post-entry amendment or protest within the applicable timeframes. For more on the protest and court timeline, see Protest Denied CIT: The 180-Day Road to Court of International Trade.

Key references

• Harmonized Tariff Schedule of the United States (HTSUS), hts.usitc.gov - official text of 9903.91.02 and U.S. note 31(c) to Subchapter III of Chapter 99.
• Federal Register, federalregister.gov - Federal Register notices implementing the Section 301 four-year review rate escalations.
• White House, whitehouse.gov - Presidential proclamations and executive orders related to Section 301 China tariff actions.
• U.S. Customs and Border Protection, cbp.gov - CSMS messages and entry guidance on Chapter 99 Section 301 declarations.
• 19 U.S.C. 2411, law.cornell.edu - Section 301 of the Trade Act of 1974, the statutory authority for these duties.