9903.94.63 Explained: South Korea Auto Parts 232 Combined 15% Rate

Key Points

• HTS 9903.94.63 applies a 15 percent combined duty rate to qualifying parts of passenger vehicles and light trucks that are products of South Korea, effective from November 1, 2025, with no announced end date as of October 7, 2026.
• The 15 percent rate is an all-in, combined rate, not an additional charge on top of the regular MFN (column 1-General or column 1-Special) duty; it replaces the regular rate for covered goods whose normal rate is less than 15 percent.
• Coverage is governed by U.S. Note 33 to subchapter III of Chapter 99, specifically subdivisions (g) and (t), and applies to parts enumerated across 134 currently in-force product-country rules.
• The code rides on the entry alongside the regular chapter 1-97 classification line; importers must report both the underlying HTS subheading and 9903.94.63 on each covered entry.
• Parts whose column 1-General or column 1-Special rate already equals or exceeds 15 percent are outside this code's scope; confirm eligibility against the current HTSUS or with your broker.

On this page

1. What 9903.94.63 covers and which program created it
2. How the 15 percent combined rate works
3. Covered South Korea product subheadings
4. How 9903.94.63 stacks with other duties
5. How the code appears on a customs entry
6. What importers should do
7. Key references

HTS 9903.94.63 is a Chapter 99 Section 232 code that imposes a 15 percent combined duty on specified parts of passenger vehicles and light trucks that are products of South Korea. It applies to the goods enumerated in subdivisions (g) and (t) of U.S. Note 33 to subchapter III of Chapter 99, but only where the normal column 1-General or column 1-Special rate for the underlying subheading is less than 15 percent. The code took effect on November 1, 2025, and carries no announced end date as of October 7, 2026.

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 9903.94.63 covers and which program created it

This code sits inside the Section 232 autos and auto parts program, which was established using authority under Section 232 of the Trade Expansion Act of 1962. Chapter 99, subchapter III of the Harmonized Tariff Schedule of the United States (HTSUS) is where all Section 232 autos and parts codes are collected, alongside the U.S. Notes that govern their scope.

The official heading text for 9903.94.63 reads: Parts of passenger vehicles and light trucks that are products of South Korea as specified in subdivisions (g) and (t) of U.S. note 33 to this subchapter, with an ad valorem (or ad valorem equivalent as provided for in subdivision (m) of U.S. note 33 to this subchapter) rate of duty under column 1-General or column 1-Special less than 15 percent.

The threshold clause is important. If a part's normal tariff rate already equals or exceeds 15 percent under column 1-General or column 1-Special, it falls outside this code entirely. Only parts with a sub-15-percent normal rate are pulled into 9903.94.63, and the 15 percent combined rate then governs.

South Korea is a deal country under the Section 232 autos framework. The rate structure for deal countries differs from the structure applied to non-deal countries. See the note on stacking below for the critical distinction.

How the 15 percent combined rate works

For deal countries such as South Korea, the 15 percent rate is combined and inclusive of the MFN rate. It is not layered on top of the regular column 1-General or column 1-Special duty. In other words, an importer does not pay the regular MFN rate plus an additional 15 percent. Instead, the total duty owed is 15 percent, and that figure already accounts for whatever the normal rate would have been.

This is the defining structural feature of 9903.94.63 and the reason it covers only parts whose normal rate is below 15 percent. Where the normal rate is already at or above 15 percent, no combined rate is needed because the existing duty is at least as high.

The rate applies on an ad valorem basis. For goods where an ad valorem equivalent is necessary, subdivision (m) of U.S. Note 33 provides the methodology.

Covered South Korea product subheadings

Coverage is defined by the subheadings listed in subdivisions (g) and (t) of U.S. Note 33. As of October 7, 2026, there are 134 product-country rules in force under this code, all effective from November 1, 2025 onward with no announced end date. One rule ended before that date and is not in scope today.

The range of covered underlying HTS subheadings is broad. A representative sample includes:

• Rubber hoses and tubes: 4009120020, 4009220020, 4009320020, 4009420020
• New pneumatic tires (passenger and light truck): 40111010, 40111050, 40112010
• Retreaded and used tires: 40121940, 40121980, 40122060
• Inner tubes: 4013100010, 4013100020
• Rubber parts and gaskets: 4016996010
• Automotive glass: 70072151, 70091000
• Springs and leaves: 732010, 73202010
• Locks and hardware: 83012000, 83021030, 830230
• Spark-ignition engines and parts: 84073100, 840732, 840733, 840734, 8409911040, 8409991040
• Compression-ignition engines: 84082020
• Pumps and compressors: 84133010, 84133090, 84139110, 8413919010, 8414308030, 84145930, 8414596540, 84148005
• Air conditioning units: 84152000
• Filters: 84212300, 84213200
• Lifting equipment: 84254900, 84269100

This is not the complete list. The full enumeration appears in subdivisions (g) and (t) of U.S. Note 33. Confirm your specific subheading against the current HTSUS before filing.

For a parallel treatment of European Union auto parts under Section 232, see our article on 9903.94.53 and the EU auto parts combined 15% rate, and for Japan auto parts, see 9903.94.43 and Japan auto parts.

How 9903.94.63 stacks with other duties

Because the 15 percent rate is combined and inclusive of the MFN duty, the stacking analysis for this code is simpler than for non-deal-country Section 232 codes. The regular column 1-General or column 1-Special rate is subsumed into the 15 percent. Do not add the two rates together.

However, other separately applicable duties, such as antidumping duties, countervailing duties, or Section 301 duties on goods of China, are separate legal instruments and are not addressed by U.S. Note 33 in the same way. If your South Korean-origin parts are also subject to any other Chapter 99 overlay, confirm the correct stacking treatment with your broker or with U.S. Customs and Border Protection (CBP) guidance before filing. The facts block for this code does not address those interactions, so do not assume any particular outcome.

The 15 percent rate does not apply to parts whose normal rate already equals or exceeds 15 percent; those goods are excluded from this code's scope by the heading text itself.

How the code appears on a customs entry

Chapter 99 codes such as 9903.94.63 are secondary classifications. On a CBP entry, each covered line item carries two HTS numbers:

1. The underlying chapter 1-97 subheading that describes the good (for example, 8409991040 for certain engine parts).
2. 9903.94.63 as a secondary, Chapter 99 line that imposes the 15 percent combined rate.

The duty is calculated on the value of the goods and assessed at 15 percent. The regular rate for the underlying subheading is superseded by the combined rate for covered South Korean-origin parts. Misclassifying a covered part or omitting the Chapter 99 secondary line can result in underpayment of duties and potential penalties. See our overview of 2026 tariff codes for broader context on Chapter 99 mechanics.

Entry date matters for determining which rate applies, particularly if you have shipments that were in transit around the November 1, 2025 effective date. For a detailed explanation of how entry date affects duty liability, see Why Does the Entry Date Change the Duty on a U.S. Import?

What importers should do

• Audit open and upcoming shipments of auto parts from South Korea against the subheadings listed in subdivisions (g) and (t) of U.S. Note 33, and verify that your broker is adding 9903.94.63 as the secondary Chapter 99 line on every covered entry line.
• Check each part's normal column 1-General or column 1-Special rate against the current HTSUS; parts at or above 15 percent are excluded from this code and should not carry 9903.94.63.
• Do not add the 15 percent combined rate on top of the MFN rate; for South Korea as a deal country, the 15 percent is all-in and inclusive of the MFN duty.
• Review prior entries filed on or after November 1, 2025, for any covered subheadings to confirm the Chapter 99 line was applied correctly; entries with errors may require a post-entry correction through CBP.

Key references

• Harmonized Tariff Schedule of the United States (HTSUS), hts.usitc.gov: The authoritative source for HTS 9903.94.63, U.S. Note 33, and all covered subheadings.
• U.S. Customs and Border Protection (CBP), cbp.gov: CBP guidance, CSMS messages, and entry instructions for Section 232 autos and parts.
• Federal Register, federalregister.gov: Federal Register notices implementing the Section 232 autos and parts program and subsequent amendments.
• White House, whitehouse.gov: Presidential proclamations establishing and modifying Section 232 autos and parts tariff measures.
• 19 U.S.C. 1862, law.cornell.edu: Section 232 of the Trade Expansion Act of 1962, the statutory authority for these measures.