Short answer: Section XVI of the HTSUS (US Harmonized Tariff Schedule) classifies machine parts in a fixed sequence. Note 1 first removes goods that never belong in Chapters 84 and 85, such as rubber belts, screws, springs, machine knives and measuring instruments. Note 2 then sends a part that is itself a good of a Chapter 84 or 85 heading to that heading, sends a part made solely or principally for one kind of machine to that machine’s parts provision, and leaves the rest for the general parts headings or, failing those, 8487 and 8548. Composite machines take the code of their principal function under Note 3, and separate components that together perform one defined function are classified as one machine under Note 4.
The machine is rarely the problem. A plant buys a packaging line once and orders spares for ten years, and the spares list is where a wrong method repeats on every entry. Below, Notes 1 to 5 are applied in order, a typical spares order is worked line by line, and the last section covers the export-control question.
Which goods leave Section XVI under Note 1?
Section XVI holds two chapters, 84 for mechanical machinery and 85 for electrical equipment, and its notes bind both. Under GRI 1 of the General Rules of Interpretation (GRI), section and chapter notes carry the same legal weight as the heading text, so a note settles the question before anyone argues about essential character. The post on reading the General Interpretative Rules correctly covers that order.
Section XVI Note 1 is a list of exclusions, lettered (a) to (q). A part named there leaves Section XVI even when it was designed for one machine and fits nothing else. The exclusions that appear most often on spare-parts invoices:
- Note 1(a): conveyor and transmission belts of plastics (Chapter 39) or of vulcanized rubber (heading 4010), and other machinery articles of soft vulcanized rubber such as O-rings (heading 4016).
- Note 1(g): parts of general use as Section XV Note 2 defines them, which covers screws, bolts and nuts of heading 7318, chain, base-metal springs, and the locks and fittings of headings 8301 and 8302, plus similar goods of plastics.
- Note 1(k): articles of Chapter 82 or 83, so machine knives and cutting blades go to heading 8208.
- Note 1(m): articles of Chapter 90, which takes pressure gauges, flow meters and other measuring instruments out of the section.
- Note 1(o): interchangeable tools of heading 8207 and brushes used as machine parts.
The chapters add exclusions of their own. One machinery buyers meet is Chapter 85 Note 1(c), which keeps machines of heading 8486 (semiconductor and flat panel display manufacturing equipment) out of Chapter 85.
How does Note 2 sort parts, and why does the order matter?
Section XVI Note 2 is three rules applied in sequence, and you stop at the first one that gives an answer.
Step 1: does a Chapter 84 or 85 heading name the part itself?
Note 2(a) says that parts which are goods of a Chapter 84 or 85 heading are classified in their own headings “in all cases”. Ball bearings (8482), valves (8481), transmission shafts and gears (8483), electric motors (8501), switches and relays (8536), control panels (8537) and cable fitted with connectors (8544) stay in those headings whatever machine they are bought for. The exception is the parts headings themselves: 8409, 8431, 8448, 8466, 8473 and 8487 in Chapter 84, and 8503, 8522, 8529, 8538 and 8548 in Chapter 85. Those headings only describe what a part goes with, so a part cannot “be” one of them at this step.
The words “in all cases” are why the “specially designed for” argument fails here. A drive shaft machined to fit one model of bagging machine is still a transmission shaft of heading 8483.
Step 2: is the part suitable solely or principally for one kind of machine?
If the part is not a named good, Note 2(b) asks whether it is suitable for use solely or principally with one kind of machine, or with several machines of the same heading (machines of 8479 and 8543 count). If it is, the part goes with that machine: usually a “Parts” subheading inside the machine’s own heading, such as 8422.90 for packaging machinery, or a dedicated parts heading, for example 8466 (machine-tool parts) or 8431 (parts of the cranes, forklifts and other handling equipment of 8425 to 8430). “Solely or principally” is a question of fact, and the evidence is ordinary: the drawing, the OEM part number and the list of machine models the part fits.
Note 2(b) also has two sentences for electronics. Parts equally suitable for 8517 network and telephone equipment and for the apparatus of 8525 to 8528 go to 8517, and parts for flat panel display modules of 8524 go to 8529.
Step 3: what happens to everything else?
Note 2(c) covers a part that is neither a named good nor dedicated to one kind of machine. It goes to the parts headings “as appropriate” and, failing that, to 8487 (machinery parts with no electrical connectors, coils, contacts or other electrical features) or 8548 (electrical parts of machinery not specified elsewhere). A classifier who reaches 8487 first has usually skipped a step.
The order changes more than the code: each heading has its own column 1 rate, and the subheading decides which Chapter 99 measures attach.
Worked example: a packaging machine spare-parts list, line by line
Take a hypothetical order. A snack producer imports spares for a vertical form-fill-seal (VFFS) machine, which forms a bag from film, fills it and seals it. The machine is packaging machinery of heading 8422; subheading 8422.30 covers machinery for filling, closing and sealing bags and other containers. The supplier’s invoice calls every line “spare part for VFFS machine”, and the importer’s item master has always coded the whole order under 8422.90. The notes sort it as follows.
| Invoice line | Rule that decides | Where it goes |
|---|---|---|
| Toothed timing belt, vulcanized rubber | Note 1(a) | 4010 (endless synchronous belts) |
| O-ring seals for the pneumatic cylinders | Note 1(a) | 4016.93 |
| Socket head cap screws and lock nuts, steel | Note 1(g) with Section XV Note 2 | 7318 |
| Compression springs for the film brake | Note 1(g) with Section XV Note 2 | 7320 |
| Serrated cross-seal knife | Note 1(k) | 8208 (machine knives and cutting blades; the subheading turns on what kind of machine it fits) |
| Pressure gauge on the air supply | Note 1(m) | Chapter 90, heading 9026 |
| Deep-groove ball bearings | Note 2(a) | 8482.10 |
| Pneumatic solenoid valve | Note 2(a) | 8481.20 (valves for pneumatic transmissions) |
| Servo motor for the film drive | Note 2(a) | 8501 |
| Cartridge heaters for the sealing jaws | Note 2(a) | 8516.80 (electric heating resistors) |
| Drive shaft machined for this model | Note 2(a) | 8483.10 |
| Toothed pulley, shipped loose | Note 2(a) | 8483.90 (toothed wheels presented separately) |
| Control cabinet fitted with contactors and relays | Note 2(a) | 8537.10 (not exceeding 1,000 V) |
| Sensor cable fitted with connectors | Note 2(a) | 8544.42 |
| Sealing jaws, machined steel, heaters not included | Note 2(b) | 8422.90 |
| Forming tube and collar for one bag width | Note 2(b) | 8422.90 |
Two of the sixteen lines end up in 8422.90. Six leave Section XVI altogether, eight go to their own Chapter 84 or 85 headings, and none reaches the 8487 residual. The lines that start arguments sit in the middle of the table: the shaft, the heaters and the control cabinet were all designed for this machine, and the supplier will say so in writing. Note 2(a) does not ask.
One line type is missing on purpose. An operator touchscreen can be a control panel of 8537, a monitor of 8528 or a unit of an automatic data processing machine of 8471, depending on what is inside the housing, and the invoice never says. That line needs the spec sheet before it gets a code.
This is the sorting TariffWolf’s bulk classification service runs on a parts file: each line comes back with a 6-digit HS subheading and the Section XVI note, heading text and CBP rulings behind it, and a line like the touchscreen, where the data does not show what the part contains, gets a clarifying question or goes to an in-house classifier instead of a guess. If your list is really the bill of materials for a machine you assemble yourself, the question becomes which lines merge into one code.
How does Note 3 classify composite and multi-function machines?
Section XVI Note 3 covers two cases: separate machines combined into one whole, and a single machine designed to perform two or more complementary or alternative functions. Unless the context requires otherwise, both are classified as the component, or the machine, that performs the principal function.
Note 3 is a legal note, so it applies under GRI 1, and the question is which function is principal. Which component gives essential character is a GRI 3(b) question that arises only when headings and notes leave a tie. Mixing up the two tests is a common error; essential character under GRI 3(b) shows where that rule really applies.
A hypothetical checkweigher shows the reasoning. It is a short conveyor with a load cell that weighs each pack in motion and pushes underweight packs off the line. On paper it is a conveyor (heading 8428 names conveyors) and weighing machinery (heading 8423 includes weight-operated checking machines). The conveyor exists to carry packs across the scale; the buyer pays for the weighing and rejecting. Under Note 3 it is classified as weighing machinery.
Three Chapter 84 notes work alongside Note 3. Note 2 sends a machine that fits a heading in 8401 to 8424 and one in 8425 to 8480 to the first group. Note 6(E) classifies a machine that works with a computer but performs some other specific function by that function, which is why a CNC lathe is a lathe. Note 8 treats a machine’s principal purpose as its sole purpose and sends a machine whose principal purpose no heading describes to 8479.
How does Note 4 treat a functional unit spread across several pieces?
Section XVI Note 4 applies when a machine, or a combination of machines, consists of individual components that together contribute to one clearly defined function covered by a Chapter 84 or 85 heading. The components may be separate or linked by piping, transmission devices or electric cables, and the whole is classified in the heading for that function.
Picture a containerized water-treatment unit: feed pumps, cartridge filters, a reverse-osmosis rack, dosing pumps, pipework and a control panel. Its function is purifying water, and subheading 8421.21 covers machinery for filtering or purifying water. Imported together as that unit, the pumps and panel get no codes of their own; the whole goes to 8421.21.
Note 4 has limits. The function must be one a Chapter 84 or 85 heading describes. Equipment that does not contribute to it (a spare-parts kit, a laptop for reports, workshop tools) is classified on its own. And Note 4 looks at goods as presented: a pump bought a year later to replace one in the unit is a pump of heading 8413.
| Note | What it classifies | The question it asks |
|---|---|---|
| Note 2 | A part imported on its own | Is it a named good, a part for one kind of machine, or neither? |
| Note 3 | Machines fitted together, or one machine with several functions | Which function is principal? |
| Note 4 | Separate components presented as one working unit | Do they together perform one function a heading describes? |
What does Note 5 mean by “machine”?
Section XVI Note 5 defines “machine” as any machine, machinery, plant, equipment, apparatus or appliance cited in the headings of Chapter 84 or 85. So a transformer or a control panel is a “machine” for Notes 3 and 4, though nobody on a plant floor would call it one. Note 6 (new in HS 2022) covers only electrical and electronic waste, heading 8549.
How are production lines shipped in several consignments classified?
A complete line usually arrives in pieces, and classification follows what is presented. GRI 2(a) covers both halves of the problem: an incomplete machine is classified as the complete one if, as presented, it has the essential character of the finished article, and a complete machine presented unassembled is classified as the complete machine.
When the pieces travel on different vessels, entry rules decide whether CBP looks at them together. Under 19 CFR 141.58, the importer of record may make a single entry for an “entity” that arrives unassembled on more than one conveyance because its size or nature prevents shipment on one. It must be ordered and invoiced as one item, classifiable as a single entity, consigned to one US person, and all portions must reach the same port within 15 calendar days of the first being unladen. The application goes to the port director at least 5 working days before the first conveyance arrives, with a proposed single HTSUS number. Portions on that entry are classified as though imported together; spare parts are entered separately; and portions that miss the window are each classified in their condition as imported.
So settle the classification of a line before it ships. Six portions arriving over five weeks without a 141.58 approval are six importations. The entry mechanics belong to the licensed customs broker; the classification and its evidence belong to the importer.
Do machine tools and fab equipment need an export classification too?
Often, and the HTS code does not answer it. On export the same equipment may need an Export Control Classification Number (ECCN) under the Export Administration Regulations (EAR) of the Bureau of Industry and Security (BIS), which is a separate determination from a separate text.
Machine tools sit in Category 2 of the Commerce Control List, where ECCN 2B001 covers numerically controlled machine tools that meet the performance parameters in that entry. Semiconductor manufacturing equipment, which on the tariff side goes to heading 8486 and to no other heading once it meets that heading’s description (Chapter 84 Note 11(D)), sits in Category 3: ECCN 3B001 covers equipment for manufacturing semiconductor devices and materials, and some lower-specification electronics production equipment falls under 3B991. Equipment that meets no parameter may be EAR99. The only reliable method is to compare the specification sheet with the entry’s parameters in Supplement No. 1 to 15 CFR Part 774; nothing in heading 8458 or 8486 predicts the result.
What mistakes come up most with Section XVI parts?
- Coding a whole spares order under the parent machine’s parts subheading. In the example above, that misplaces fourteen of sixteen lines.
- Reaching for 8487 or 8548 before working through Note 2(a) and Note 2(b).
- Treating a supplier’s “specially designed for” letter as decisive for a bearing, valve, motor or shaft.
- Copying a code from an old ruling without checking its date and facts. Under 19 CFR 177.9, a ruling applies to the transaction it describes, and statistical suffixes change between HTSUS revisions.
Related reading
- How to calculate US import duty when tariffs stack on one HTS line
- How to classify a product from description to HTS code
- Section 301 China tariffs: lists, rates, exclusions and how to lower the duty
- The forced-labor Section 301 tariff: 9903.05 headings by country, rates and exemptions
Frequently asked questions
Is a spare part classified with the machine it is made for?
Only if Section XVI Note 1 does not exclude it and no Chapter 84 or 85 heading names it as a good in its own right. Bearings, valves, motors, shafts and switches go to their own headings under Note 2(a) even when they fit one machine only. A part with no heading of its own that is suitable solely or principally for one kind of machine goes with that machine under Note 2(b).
How do Note 3 and Note 4 of Section XVI differ?
Note 3 covers machines fitted together into one whole, or one machine with several functions, and classifies them by the principal function. Note 4 covers separate components, linked by pipes, cables or transmission devices, that together perform one function a Chapter 84 or 85 heading describes, and classifies the whole by that function. Both apply under GRI 1.
When do machine parts go to heading 8487 or 8548?
Only at the end of Note 2(c), when a part is not excluded by Note 1, is not a good of any Chapter 84 or 85 heading, is not dedicated to one kind of machine and fits no other parts heading. Heading 8487 takes such parts without electrical features; 8548 takes the electrical ones.
Can a production line shipped in several containers be classified as one machine?
Yes, if the line is a functional unit under Note 4 or a complete machine under GRI 2(a) and the portions are entered together, which 19 CFR 141.58 allows for an unassembled entity arriving at one port within 15 days. Portions entered separately are classified as imported.
Section XVI rewards doing the steps in order: the Note 1 exclusions, the part’s own heading, the machine it is dedicated to, the residual headings, and only then the composite and functional-unit questions for whole machines. For most machinery importers the fix is a parts master in which every SKU records which note decided its code and what evidence supports “solely or principally”.
If you have a spares master or a supplier parts list that was coded by parent machine, TariffWolf’s bulk classification service takes each line to the 6-digit subheading with the Section XVI note and CBP rulings that support it, routes the ambiguous lines to an in-house classifier, and leaves the last four digits of the HTS number to your own classifier or broker. You can send a sample parts file through the contact page and read the justifications before committing the full catalog.
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