Section XVI · Nuclear reactors, boilers, machinery and mechanical appliances; parts
8409.91
Suitable for use solely or principally with spark-ignition internal combustion piston engines (including rotary engines):
Chapter
Nuclear reactors, boilers, machinery and mechanical appliances; parts
Heading
The product family within the chapter
Subheading
The specific good, identical worldwide
The first six digits are the same in every country that uses the Harmonized System. The United States adds two more for the tariff rate and, often, two more for statistics — which is why the rates below are listed against 8- and 10-digit numbers rather than against this code.
How the schedule reaches this code
- 84Nuclear reactors, boilers, machinery and mechanical appliances; parts
- 8409Parts suitable for use solely or principally with the engines of heading 8407 or 8408:
- Other:
- Suitable for use solely or principally with spark-ignition internal combustion piston engines (including rotary engines):
Published US duty rates
Duty is set at the 8- or 10-digit line, not at this 6-digit subheading, so more than one rate can sit under this code.
- 8409.91.10Cast-iron parts, not advanced beyond cleaning, and machined only for the removal of fins, gates, sprues and risers or to permit location in finishing machinery
- General
- Free
- Special (FTA)
- —
- Column 2
- 10%
No preferential rate published.
Countries without normal trade relations.
- 8409.91.30.00Aluminum cylinder headsNo., kg
- General
- 2.5%
- Special (FTA)
- Free (A,AU,B,BH,CL,CO,D,E,IL,JO,KR,MA,OM,P,PA,PE,S,SG)
- Column 2
- 35%
Only if the goods qualify under one of these programs.
Countries without normal trade relations.
- 8409.91.50Other
- General
- 2.5%
- Special (FTA)
- Free (A*,AU,B,BH,CL,CO,D,E,IL,JO,KR,MA,OM,P,PA,PE,S,SG)
- Column 2
- 35%
Only if the goods qualify under one of these programs.
Countries without normal trade relations.
- 8409.91.92For marine propulsion engines
- General
- 2.5%
- Special (FTA)
- Free (A,AU,BH,CL,CO,D,E,IL,JO,KR,MA,OM,P,PA,PE,S,SG)
- Column 2
- 35%
Only if the goods qualify under one of these programs.
Countries without normal trade relations.
- 8409.91.99Other
- General
- 2.5%
- Special (FTA)
- Free (A*,AU,BH,CL,CO,D,E,IL,JO,KR,MA,OM,P,PA,PE,S,SG)
- Column 2
- 35%
Only if the goods qualify under one of these programs.
Countries without normal trade relations.
Schedule footnotes
- See 9903.88.03.
A reference to Chapter 99 means an additional action — a Section 232 or 301 measure, an exclusion, or a quota — applies on top of the rate above.
This is the listed rate. Antidumping and countervailing duty orders, Chapter 99 actions and preference qualification all change what is actually collected, and classification is a judgement about your goods. Verify with your licensed customs broker before you file.
Other subheadings in heading 8409
Source: U.S. International Trade Commission (USITC) — 2026 HTS Revision 12, released 2026-07-21, published at hts.usitc.gov. A U.S. Government work in the public domain.