HTS heading 8404 · Chapter 84
HTS 8404: Auxiliary plant for use with boilers of heading 8402…
HTS heading 8404 covers auxiliary plant for use with boilers of heading 8402 or 8403 (for example, economizers, super-heaters, soot removers, gas recoverers); condensers for steam or other vapor power units; parts thereof. It has 3 tariff lines with a duty rate; the general (MFN) rates are 3.5% (2 lines), 5% (1 line).
Imports may also owe Chapter 99 tariffs (Section 232, 301 or 201) depending on origin and date, plus the Merchandise Processing Fee and, by sea, the Harbor Maintenance Fee.
Rates from the 2026 HTS Revision 22, effective October 30, 2026. Source: U.S. International Trade Commission.
Tariff lines and duty rates
| HTS code | Description | General | Special | Column 2 | Estimate |
|---|---|---|---|---|---|
| 8404.10.00 | Auxiliary plant for use with boilers of heading 8402 or 8403 | 3.5% | Free (A*,AU,BH,CL,CO,D,E,IL,JO,KR,MA,OM,P,PA,PE,S,SG) | 45% | |
| 8404.10.00.10 | Economizers[t] | Estimate → | |||
| 8404.10.00.50 | Other[t] | Estimate → | |||
| 8404.20.00.00 | Condensers for steam or other vapor power units[t] | 5% | Free (A*,AU,BH,CL,CO,D,E,IL,JO,KR,MA,OM,P,PA,PE,S,SG) | 45% | Estimate → |
| 8404.90.00.00 | Parts[kg] | 3.5% | Free (A*,AU,BH,CL,CO,D,E,IL,JO,KR,MA,OM,P,PA,PE,S,SG) | 45% | Estimate → |
5 lines shown. Statistical suffixes (the last two digits) inherit the rate of the 8-digit subheading above them.
Example: base duty and fees on $10000
For HTS 8404.10.00 at the general rate of 3.5%, shipped by ocean, before any Chapter 99 tariffs:
| Base duty (3.5%) | $350.00 |
| Merchandise Processing Fee (0.3464%, min $34.58) | $34.64 |
| Harbor Maintenance Fee (0.125%) | $12.50 |
| Duty and fees | $397.14 |
Origin-specific tariffs can multiply this. Run this example from China or from Mexico to see every line.
Special program codes in this heading
- A, A*, A+
- Generalized System of Preferences (GSP)
- AU
- U.S.–Australia FTA
- BH
- U.S.–Bahrain FTA
- CL
- U.S.–Chile FTA
- CO
- U.S.–Colombia Trade Promotion Agreement
- D
- African Growth and Opportunity Act (AGOA)
- E, E*
- Caribbean Basin Economic Recovery Act
- IL
- U.S.–Israel FTA
- JO
- U.S.–Jordan FTA
- KR
- U.S.–Korea FTA (KORUS)
- MA
- U.S.–Morocco FTA
- OM
- U.S.–Oman FTA
- P, P+
- CAFTA-DR
- PA
- U.S.–Panama Trade Promotion Agreement
- PE
- U.S.–Peru Trade Promotion Agreement
- S, S+
- USMCA (United States–Mexico–Canada Agreement)
- SG
- U.S.–Singapore FTA
A special rate applies only when the goods qualify under that program's rules of origin and the claim is made at entry.