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Last updated 7 November 2026 · every figure recomputed from the sources listed at the foot of this page

Semiconductor Articles: The Two TPP and DRAM Bands Behind a 25% Overlay

Most tariff thresholds are about weight, value or origin. This one is about arithmetic throughput. Heading 9903.79.01 adds 25 percent to semiconductor articles, and U.S. note 39(b) defines “semiconductor articles” not by a product list but by two numeric bands a chip either falls inside or does not. This page prints both bands, the formula that computes the first number, all 9 headings in the family, and the eight carve-outs the note grants.

What the overlay actually covers

The family has 9 headings. One of them, 9903.79.01, carries the additional duty: its general column reads “The duty provided in the applicable subheading + 25%”. The other 8 headings (9903.79.02, 9903.79.03, 9903.79.04, 9903.79.05, 9903.79.06, 9903.79.07, 9903.79.08, 9903.79.09) all print the same shape — “the duty provided in the applicable subheading” — which means the base rate and nothing on top. There is no heading in the family that prints “No change”, and that absence matters: “No change” in Chapter 99 usually means a provision has been switched off, while “the duty provided in the applicable subheading” means the heading is live but adds zero. Reading those two as the same thing is the most common misreading of this chapter.

So the question a shipper actually faces is not “is there a semiconductor tariff” but “does my article fall inside the definition that heading 9903.79.01 points at”. Everything below is that definition.

The first band: TPP 14,000 to 17,500 with 4,500 to 5,000 GB/s

U.S. note 39(b) names three subheadings — 8471.50, 8471.80, 8473.30 — and then says the imported product must be a logic integrated circuit, or an article containing one, that meets the technical parameters of having:

“a total processing performance greater than 14,000 and less than 17,500, and a total DRAM bandwidth greater than 4,500 GB/s and less than 5,000 GB/s”

Note the word and. A part that clears the processing band but misses the bandwidth band is outside the definition, and so is one that clears bandwidth and misses processing performance. Both conditions have to hold at once, which is why a datasheet that publishes only TOPS cannot settle the question.

The second band: TPP 20,800 to 21,100 with 5,800 to 6,200 GB/s

“a total processing performance greater than 20,800 and less than 21,100, and total DRAM bandwidth greater than 5,800 GB/s and less than 6,200 GB/s”

The two bands are narrow and disjoint. Band one spans 14,000 to 17,500 in processing performance; band two spans 20,800 to 21,100. There is a wide gap between them — a chip at 18,000 TPP is inside neither — and each band carries its own bandwidth window, so the pairs are not interchangeable. This is not a de minimis-style floor where more is always dutiable; it is a pair of islands, and an article outside both is not a semiconductor article for this note's purposes no matter how fast it is.

This table is wider than the screen: scroll it sideways to reach every column.

Source: USITC · checked 7 November 2026, 00:35 UTC.

How the first number is computed

TPP is defined, not measured:

“total processing performance (TPP) is 2 × “MacTOPS” × “bit length of the operation,””

Three consequences follow. First, the figure aggregates over all processing units on the integrated circuit, so a multi-die package has one TPP, not one per die. Second, the multiplier of 2 is a bookkeeping convention — one multiply-accumulate counts as two operations because datasheets count it that way — which means 2 × MacTOPS may equal the TOPS or FLOPS a vendor prints on the product sheet. Third, the bit length in the formula is the largest input bit length of the multiply operation, so a chip that advertises a wide accumulator but multiplies narrow inputs is scored on the narrow number.

Every heading in the family, and what scopes it

The table below is the whole family in heading order, with the rate each one prints and the note subdivision that does the scoping. Eight of the nine headings exist to carve something out of the overlay: data-centre use, repairs and replacements, research and development, startups, non-data-centre consumer electronics, non-data-centre civil industrial use, and public-sector use.

This table is wider than the screen: scroll it sideways to reach every column.

Source: USITC (United States International Trade Commission) · checked 7 November 2026, 00:34 UTC.

The eight carve-outs, counted

Note 39(a) lists 8 groups of headings that the 9903.79.01 overlay does not stack on top of — 43 distinct Chapter 99 headings in total. The groups run from the passenger-vehicle headings through the aluminium, steel and copper family, the Canada and Mexico country blocks, and the reciprocal-tariff blocks. The pattern is the one that governs most of Chapter 99: where two overlays could both reach the same article, the note picks a winner rather than letting both apply. An importer who assumes stacking without reading the carve-out list overstates the duty by the whole amount of the loser.

Where the base rates sit

The definition names three subheadings, and all three are cheap in the base schedule. Across the 14 lines printed under them, 8 carry a Free general rate; the rest are stems without a rate of their own.

This table is wider than the screen: scroll it sideways to reach every column.

Source: USITC · checked 7 November 2026, 00:34 UTC.

The semiconductor devices themselves live in chapter 85, and there the picture is even flatter: across 17 rated lines under headings 8541 and 8542, 14 print Free.

This table is wider than the screen: scroll it sideways to reach every column.

Source: USITC · checked 7 November 2026, 00:34 UTC.

That contrast is the whole economics of this page. The base schedule charges nothing on the chips; the 25 percent arrives entirely through Chapter 99, and only for articles that land inside one of the two bands. A memory module at Free plus 25 percent is a different business from a memory module at Free.

What to do with this in a classification file

Four steps, in order. First, confirm the article is classifiable in one of 8471.50, 8471.80, 8473.30 — if it is not, the note never reaches it. Second, get the datasheet figures for total processing performance and total DRAM bandwidth, computed the way the note defines them rather than the way the marketing page reports them. Third, check which band, if either, the pair falls inside. Fourth, if the article is inside a band, check whether one of the eight use-based carve-outs applies, because those turn 25 percent back into zero without changing the classification at all.

The failure mode to avoid is treating “contains a logic integrated circuit” as the test. It is a precondition, not the test: the note requires the article to be a logic IC or contain one and meet a numeric band. A laptop contains several and is not, on that ground alone, a semiconductor article.

Reading the rest of the chapter this way

This page is one of a set that reads Chapter 99 by its numeric tests rather than by its product names. The Section 232 metal-content page does the same thing with a 15 percent weight threshold; the aircraft page does it with a 15,000 kg and a 30,000 kg line; the de minimis data page does it with a value floor. The shape is identical in all four: a heading that reprices an article, plus a measurement that decides whether the heading reaches it. Once you have read one, the others are the same exercise with a different unit.

Two cautions apply to all of them. The bands in this note are technical parameters that can be redefined by a later modification, and the export this page was built from is a snapshot — the source line under every table carries the timestamp it was read. And a note-based exclusion is not the same as a refund: an article that leaves the definition was never dutiable under this heading, which is a classification position you have to be able to support, not a claim you file afterwards.

Frequently asked questions

What is the TPP threshold for the 25% semiconductor tariff?

U.S. note 39(b) prints two bands. Band one is a total processing performance greater than 14,000 and less than 17,500 combined with a total DRAM bandwidth greater than 4,500 and less than 5,000 GB/s. Band two is TPP greater than 20,800 and less than 21,100 with bandwidth greater than 5,800 and less than 6,200 GB/s. An article inside either band, classifiable in 8471.50, 8471.80 or 8473.30, is a semiconductor article for heading 9903.79.01.

Which HTS subheadings does note 39 reach?

It names three: 8471.50, 8471.80, 8473.30. The note's definition of semiconductor articles is limited to products classifiable in those provisions, so a chip classified elsewhere is outside it even if it meets both numeric bands.

How is total processing performance calculated?

TPP is 2 times MacTOPS times the bit length of the operation, aggregated over all processing units on the integrated circuit. The 2 reflects the convention of counting one multiply-accumulate as two operations, which is why 2 times MacTOPS may match the TOPS or FLOPS a datasheet prints.

Does the 25% stack on top of other Chapter 99 duties?

Not on the 8 groups of headings note 39(a) lists — 43 headings covering vehicles, aluminium, steel and copper articles, the Canada and Mexico blocks and the reciprocal-tariff headings. The note names a winner instead of letting both overlays apply.

Do the 9903.79 carve-outs change the classification?

No. Headings 9903.79.02, 9903.79.03, 9903.79.04, 9903.79.05, 9903.79.06, 9903.79.07, 9903.79.08, 9903.79.09 all restate the base duty, so an article that qualifies for one of them keeps its chapter 84 or 85 classification and simply does not pay the 25 percent. That is a different thing from a refund claim.

What do the chapter 85 base rates look like?

Across the 17 rated lines under headings 8541 and 8542, 14 print Free in the general column. The duty on a covered article comes entirely from the Chapter 99 overlay, not from the base schedule.

Sources

• USITC — Chapter 84 REST export (8471.50 / 8471.80 / 8473.30 base rates) (read 2026-11-07T00:34:57Z, sha256 83a1e1dc1601fddb…)
• USITC — Chapter 85 REST export (8541 / 8542 semiconductor base rates) (read 2026-11-07T00:34:59Z, sha256 b23c7fdf8255d691…)
• USITC (United States International Trade Commission) — Chapter 99 REST export re-read by this task; 3,350 rows. Byte-identical to the copy batch 1 read on 2026-11-06 (read 2026-11-07T00:34:48Z, sha256 e55de042e0cb6b67…)
• USITC — Chapter 99 PDF (14,005,269 bytes, HTS Revision 22 (2026)); read through pdftotext -layout for the U.S. notes that carry the numeric thresholds and the phased rate tables (read 2026-11-07T00:35:05Z, sha256 290eee3d064837a0…)

Every figure above is recomputed from the datasets listed here at render time; the dataset vintage and each source's check timestamp are printed with it. This page extends the prototype that already earns search traffic on the same mechanism. Rates are informational, not a binding customs determination: confirm the classification and the entry with CBP before shipping.