Quick answer
"Part of a machine" is one of the hardest calls in the HS. The Notes give a strict three-step hierarchy most declarants skip.
A bracket, a motor, a cable, a touchscreen: is it "the thing itself" or "a part of the machine it serves"? Billions in duty ride on that question.
Step 1: is it excluded or a good of its own heading?
Note 1 to Section XVI excludes many articles outright (belts of plastics, tools of Chapter 82…). Note 2(a): parts which are themselves goods of a specific heading go to that heading — an electric motor is always 8501, a pump always 8413, even when clearly destined for one machine.
Step 2: sole or principal use
Note 2(b): parts suitable for use solely or principally with a particular machine are classified with that machine (or in its dedicated parts heading, e.g. 8473 for office machines, 8708 for vehicles under the parallel Section XVII notes). Evidence matters: design drawings, fitment lists, marketing.
Step 3: the residual
Note 2(c): otherwise, parts fall to residual headings such as 8487/8548. Auditors treat heavy use of residual headings as a red flag.
Chapter 90 nuance
Instruments follow similar rules via Chapter 90 Note 2, but with stricter exclusions. Accessories (non-essential add-ons) are treated differently from parts — an accessory can only be classified with the machine where the heading text or notes say so.
Common battlegrounds
- Touchscreens and display modules: 8524 (flat panel display modules under HS 2022) vs parts headings
- Vehicle vs machine parts: Section XVII Note 2 excludes machinery of 84/85 from "parts of vehicles"
- Fasteners "for" a machine: general-use articles of Note 2 to Section XV never become machine parts
Practical rule
Never start from "it is a part". Start from "what is this object, on its own?" — then let the Notes decide whether its destiny with a machine changes anything.
2026 U.S. legal authority and practice note
Legal review date: September 5, 2026. The USITC online HTSUS identified 2026 Revision 18 on this review date. The version effective on the actual entry date controls.
Article-specific legal clarification
The word “part” is not a default classification. Apply the relevant Section and Chapter Notes first, including exclusions and principal-use provisions; then determine whether the imported article is a complete good under GRI 2(a), a specifically named good, a part solely or principally used with another article, or a general-use part classified elsewhere.
Hierarchy and weight of classification authority
| Authority | U.S. legal significance |
|---|---|
| HTSUS heading/subheading text and Section/Chapter/Additional U.S. Notes | Statutory tariff text; apply through the GRIs and U.S. Additional Rules of Interpretation. |
| WCO Explanatory Notes | Persuasive guidance for interpreting the international HS, but not U.S. statutory text. |
| CBP ruling under 19 CFR Part 177 | Binding on CBP for the requester and merchandise covered by the ruling's facts, subject to modification/revocation and later legal changes; similar CROSS rulings may be persuasive. |
| Court of International Trade / Federal Circuit decision | Controlling judicial precedent within its jurisdiction; factual and procedural posture must match. |
| Broker, vendor or database code | A lead only; it does not transfer the importer's legal responsibility. |
Importer-of-record standard and current-entry controls
Under 19 U.S.C. 1484, the importer of record must use reasonable care to enter, classify and value the merchandise and provide information needed for admissibility, even when a licensed broker files the entry. Negligent, grossly negligent or fraudulent material statements or omissions can be penalized under 19 U.S.C. 1592. Preserve a written classification file and records required by 19 U.S.C. 1508 and 19 CFR Part 163, generally for five years.
Before relying on this article for an entry, independently verify: 1. the exact 10-digit HTSUS number in the current schedule and any required Chapter 99 number; 2. customs value under 19 U.S.C. 1401a and nonpreferential/preferential origin; 3. Section 301/232, safeguard, quota and exclusion status on the entry date; 4. every potentially relevant AD/CVD written scope—scope text is dispositive and HTS references are only for convenience; and 5. all PGA admissibility, certification, labeling, reporting and ACE data requirements.
For a recurring, novel or high-value classification, request a prospective CBP ruling under 19 CFR Part 177 with complete facts. An FAQ, search result or AI output is not a ruling and does not by itself establish reasonable care.
Official legal sources
- USITC — Current Harmonized Tariff Schedule of the United States
- CBP — User fee table: MPF rate and FY 2026 minimum/maximum
- CBP — Harbor Maintenance Fee
- CBP — ACE: filing customs and Partner Government Agency data
- USTR — Section 301 tariff actions and exclusion search
- BIS — Section 232 steel and aluminum measures
- Commerce — AD/CVD FAQs, scope and circumvention rules
- Commerce — ACCESS AD/CVD proceeding search
- CBP — UFLPA rebuttable presumption
- CPSC — Certificates and mandatory eFiling guidance
- FDA — Importing food products into the United States
- EPA — TSCA requirements for importing chemicals
- PHMSA — Lithium battery transportation requirements
- FCC — Equipment authorization
- eCFR — 19 CFR Part 177: administrative rulings
- eCFR — 19 CFR Part 134: country-of-origin marking
- eCFR — 19 CFR Part 163: recordkeeping
> Legal notice: “Classifying parts and accessories: the Section XVI, XVII and Chapter 90 logic” provides general information, not transaction-specific legal advice or an agency ruling. Verify the law, tariff edition, facts and agency instructions in effect on the entry date.
Editorial note
Prepared by the Global HS Code Checker Editorial Team for customs-classification, tariff and import-policy research. The correct code and applicable measures may change with the merchandise's actual characteristics, jurisdiction, entry date and supporting record. Verify the current tariff, governing measures and competent customs authority before filing an entry.