Overlapping Chapter 99 headings can make Section 301 tariff stacking look more complicated than it is. For Chinese-origin merchandise moving from 9903.88.15 at 7.5% to 9903.91.06 at 25%, the central rule is replacement, not addition, but separate trade remedies may still produce cumulative duty exposure.
Why the 25% Rate Replaces the 7.5% Rate
The New Heading Supersedes the Original List Heading
When a product previously subject to the List 4A rate under 9903.88.15 becomes covered by 9903.91.06, the two headings generally do not apply cumulatively. The 25% additional duty under 9903.91.06 replaces the 7.5% additional duty under 9903.88.15 for covered entries made on or after the applicable effective date.
The correct calculation is therefore the ordinary duty rate under the product's Chapter 1-97 classification, plus the 25% Section 301 rate, along with any other independently applicable duties. It is not the ordinary duty rate plus 7.5% plus 25% for the same underlying Section 301 China action.
This treatment reflects the purpose of the 2024 review headings. They establish revised rates for selected products that were already within the broader Section 301 framework. Applying both the original list heading and the revised heading would charge the merchandise twice under the same tariff action.
Effective Dates and Product Scope Still Control
The replacement rule applies only when the product is within the scope of 9903.91.06 and the entry falls on or after its January 1, 2026 effective date. Classification, country of origin, product description, and applicable tariff notes must all support use of the new heading.
Products that remain within List 4A but are not transferred to a higher-rate 2024 review heading generally continue at 7.5%. Lists 1-3 generally remain subject to their existing 25% rates. The presence of a familiar Chapter 1-97 classification in a historical list does not, by itself, establish the correct current Chapter 99 treatment. Entry teams must evaluate the current tariff status for the specific product and entry date.
When Section 301 Duties Can Still Stack
Replacement Is Different From Cumulative Trade Actions
The conclusion that 9903.91.06 replaces 9903.88.15 should not be converted into a broad rule that Section 301 duties can never stack. Replacement occurs when two headings represent the original and revised rates for the same tariff action. Cumulative treatment may apply when separate trade actions independently cover the same merchandise.
For example, the separate 12.5% forced-labor Section 301 duty under 9903.05.31, effective July 24, 2026, generally applies in addition to either an original China list rate or an applicable 2024 review rate. Merchandise covered by 9903.91.06 may therefore face the 25% review rate and the separate 12.5% duty, assuming the product is within the scope of both actions and no exception applies.
That outcome is not double assessment under a single action. It is the cumulative application of distinct tariff measures. The legal basis, scope language, exclusions, effective dates, and Chapter 99 instructions for each measure determine whether the duties are additive.
Other Trade Remedies Require Separate Analysis
Section 232 duties, antidumping duties, countervailing duties, safeguard duties, and other special tariffs may also apply alongside Section 301 duties. Each program has its own rules, product coverage, country scope, exclusions, and reporting sequence.
A sound tariff analysis should identify every potentially applicable measure before calculating landed duty cost. Compliance teams should not assume that a nonstacking result between 9903.88.15 and 9903.91.06 eliminates other additional duties.
The practical distinction is straightforward. Two headings that express an old and new rate for the same action generally result in replacement. Two headings arising from separate actions may be cumulative. Because Chapter 99 instructions can modify that general approach, the applicable notes and entry requirements should be reviewed for every affected product.
Filing Controls, Exclusions, and Duty Recovery
Brokers Should Update Entry Logic and Client Instructions
Customs brokers and importers should ensure that classification databases, product masters, broker instructions, and landed cost models no longer apply 9903.88.15 to merchandise properly covered by 9903.91.06. Leaving both headings active can create an overpayment. Leaving only the former 7.5% heading active can create an underpayment and potential compliance exposure.
Entry controls should test the Chapter 1-97 classification, Chinese origin determination, entry date, applicable exclusion status, and all potentially relevant Chapter 99 headings. The control should also distinguish between replacement headings and separate cumulative measures. This is especially important when a product can be subject to several special duty programs with different effective dates.
The 178 remaining exclusions claimed under 9903.88.69 and 9903.88.70 are scheduled to expire at 11:59 p.m. Eastern on November 9, 2026, unless extended. After expiration, affected merchandise generally reverts to the applicable original list rate or 2024 review rate. Importers relying on those exclusions should prepare classification and costing systems for the transition rather than waiting until entries reject or duty accruals change.
Incorrect Assessments May Create Recovery Opportunities
Entries filed with both 9903.88.15 and 9903.91.06 may warrant review for potential overpayment. Depending on entry status and timing, correction may be available through a post-summary correction, protest, or another appropriate customs process. Liquidation status and procedural deadlines are critical.
Section 301 duties are also typically eligible for duty drawback when statutory requirements are satisfied. Imported merchandise that is later exported or destroyed may support recovery of qualifying additional duties, subject to the applicable drawback method, documentation, and filing rules.
A disciplined review should separate duties paid correctly from amounts generated by duplicate Chapter 99 treatment. That distinction supports accurate refund claims, reliable financial accruals, and defensible communications with importer clients.
- On October 7, 2026, USTR issued a Federal Register notice confirming continuation of the 2018 Section 301 China actions after receiving domestic industry requests, so Lists 1-3 remain at 25% and List 4A at 7.5% with no rate changes.
- The 178 remaining Section 301 product exclusions (claimed under 9903.88.69 and 9903.88.70) expire at 11:59 p.m. Eastern on November 9, 2026; no extension notice had been published as of early November 2026, after which covered goods revert to the applicable list or 2024 review rate.
- October 2026 trade compliance analyses and HTS notes confirm that a 2024 four-year review heading such as 9903.91.06 (25% additional duty, effective January 1, 2026) replaces rather than stacks with an original list heading such as 9903.88.15 (7.5%); CBP CSMS 62411889 (September 26, 2024) directs filers to enter covered goods under the 9903.91 heading.
- A separate 12.5% forced-labor Section 301 duty on most Chinese-origin goods (effective July 24, 2026 under 9903.05.31) continues to apply on top of either original list or 2024 review rates.
- No new CBP guidance on stacking original 301 lists with 2024 review increases appeared in the past 30 days, and recent X discussions did not specifically address this 9903.88/9903.91 overlap.
Frequently Asked Questions
Do 9903.88.15 and 9903.91.06 Stack?
No. For merchandise covered by 9903.91.06 on or after January 1, 2026, the 25% rate generally replaces the 7.5% rate under 9903.88.15. Both headings should not be used to assess 32.5% under the same Section 301 China action.
Can Two Different Section 301 Duties Apply to One Product?
Yes. Separate Section 301 actions may apply cumulatively when their governing scope and tariff instructions require it. The 12.5% duty under 9903.05.31 may apply in addition to an original list rate or a 2024 review rate. This is distinct from replacing an old rate with a revised rate.
What Happens When a Section 301 Exclusion Expires?
Merchandise entered after an exclusion expires generally becomes subject to the underlying Section 301 rate unless another exclusion or exception applies. Importers should confirm the entry date rules, applicable list, 2024 review coverage, and current Chapter 99 reporting requirements.
How Should an Incorrectly Stacked Entry Be Corrected?
The appropriate procedure depends on whether the entry remains unliquidated, whether post-summary correction is available, and whether a protest deadline applies. Brokers and importers should identify the duplicated duty, preserve supporting classification records, and use the customs correction mechanism available for the entry's status.
Are Section 301 Duties Eligible for Duty Drawback?
Section 301 duties are typically recoverable through duty drawback when the imported merchandise and subsequent exportation or destruction satisfy the applicable requirements. Eligibility depends on the drawback provision, records, time limits, and ability to establish the required relationship between imports and exports.
How Stable Software Can Help
A Flat-License Drawback Model for Customs Brokers
Incorrect tariff stacking and changing exclusion status can leave importers with substantial duty recovery opportunities. Stable Software's DrawbackAI gives U.S. customs brokers a duty drawback platform they can white-label for importer clients while filing claims under their own filer code.
Stable Software charges a flat software license and never takes a percentage of the refund. That model allows brokers to build a drawback service without surrendering part of the client's recovery to a percentage-based provider. Customs brokers reviewing Section 301 payments, exported merchandise, and potential duplicate assessments can evaluate DrawbackAI as part of a broader duty recovery strategy.
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