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Section 301 Isn't Just 25%: A Census of Every Chapter 99 Additional-Duty Rate Tier

Say "Section 301" in a sourcing meeting and someone will answer "25 percent, right?" The instinct is understandable — the headline China actions landed at 25% — but it quietly falsifies the legal reality. The Chapter 99 provisions carrying these additional duties form a ladder of discrete rates, and importers who plan against "25%" alone misprice everything above and below it.

We ran a full census of our local mirror of the USITC Chapter 99 additional-duty extraction: 637 provisions, every one under statistical suffix 9903. Of these, 245 carry a machine-parseable "+X%" surcharge in their General column, spanning 41 discrete rate tiers — from a wall of +25% provisions (49 rows) up to a +200% ceiling. This page is the tier ladder, the extreme cases, and the counting method, all recomputed from the source file at generation time.

What we counted, exactly

The corpus is our structured mirror of the USITC REST-stop export of subchapter III statistical suffixes 9900–9999 (generated 2026-10-10, every row carrying its retrieval stamp; column values cross-checked against our main-table mirror upstream, with 55 corrections applied during ingestion). Each record carries the HTS provision number, a measure label, and the General/Special rate columns a broker actually reads.

• Additive tier: the General column contains a literal "+X%" surcharge — 245 provisions. We take the first such figure per row.
• Free: the column begins with "Free" and parses no percentage — 6 provisions.
• Zero additive: a parsed "+0%" — 5 provisions, kept inside the additive set.
• Unparsed text: quota-allocation and TRQ wording that names no percentage — 386 provisions, excluded from the tier ladder and disclosed rather than guessed.

One counting disclosure matters: this is a census of provisions, not products. A high-volume 8-digit line can sit behind a small provision and vice versa; weighting by trade flows is a different exercise and a different dataset.

The tier ladder, ranked by frequency

The modal tier is exactly where folklore puts it: +25%, covering 49 of the 245 parseable provisions (20.0%). But the long tail around it is where planning errors happen: +15% covers another 44 provisions, +12.5% another 38, and the ladder keeps stepping down through 10%, 7.5% and smaller increments before it bottoms out at zero.

Top 12 of 41 tiers by provision count; ties broken toward the lower rate.

Read the ladder as a pricing-risk menu: if your 8-digit line maps into Chapter 99 at all, its add-on is drawn from this distribution. 100 of the 245 parseable provisions carry 25% or more — and the folklore reflex prices only the single modal tier, leaving every smaller step (+15%, +12.5%, +10%) and the entire triple-digit club misquoted.

The ceiling: 200% and the triple-digit club

At the far end of the ladder sits a pair of sibling provisions, 9903.85.67 and 9903.85.68, each carrying an additional +200%. Between the folklore rate and that ceiling lies a triple-digit club of 7 provisions at +100% or more:

Every provision at +100% or more; add-ons sit on top of the applicable subheading rate.

Nobody budgeting "25% Chinese tariff" against a line that lands here is wrong by a rounding error — they are wrong by a factor of eight.

Where the tiers live: U.S.-note families

Subchapter III attaches each provision to a program through numbered U.S. notes in the HTS. The census spans 19 distinct note families — the China Section 301 actions are the best-known block, but not the only one whose tiers you need to price. The largest families and the rate each most commonly adds:

Top 8 of 19 note families by provision count; dominant add-on within each family.

Program identity changes the question you ask — exclusions, review schedules and effective dates differ — but the tier arithmetic itself is shared, which is why a single census can serve all of them.

Effective dates: the ladder still moves

41 provisions in the corpus carry an explicit effective date, spanning 2020-06-04 through 2026-11-10. That upper bound is not a typo in our data — 5 provisions were dated in the future relative to this build, i.e. surcharges legislated but not yet collectable at generation time. A tier census is therefore a snapshot with a shelf life: we regenerate it from the source file on every rebuild, and a drift alarm fails the build loudly if the audited figures move.

What to do with the ladder

Three practical moves follow directly from the census:

1. Price the provision, not the folklore. Before quoting a China-origin order, resolve the 8-digit line's Chapter 99 overlay; the +25% reflex misses 80.0% of the parseable provisions.
2. Audit the stack. The General column's "+X%" is additive to the MFN rate in the applicable subheading — model the total on our duty calculator before committing landed-cost math.
3. Watch the dated rows. Future-effective provisions change quotes mid-contract; if a line of yours sits behind one, monitor the notice stream the way you monitor FX.

A worked example ties the census together. Take a line whose General column reads "The duty provided in the applicable subheading + 7.5%". Under the folklore reading you budget nothing beyond the MFN rate; under the census reading, +7.5% is a recognized tier, your quote carries real additional duty, and your competitor pricing it at zero will eat the difference at entry.

For the base-rate side of the same coin, see our full census of the highest US tariff lines; for line-level incidence of the China actions, the Section 301 line-exposure map and the Section 301 primer are companion pieces.

Frequently asked questions

1. Is every Section 301 additional duty 25%?

No. Across the 637 Chapter 99 provisions in our mirror, 245 carry a parseable “+X%” surcharge and those span 41 distinct rates. +25% is the single largest group (49 provisions, 20.0%), but +15%, +12.5%, +10% and smaller steps all occur, up to a +200% ceiling.

2. What is the highest additional-duty rate in Chapter 99?

The maximum in the current corpus is +200%, carried by provisions 9903.85.67 and 9903.85.68. A further 5 provisions sit at +100%. These apply in addition to the applicable subheading rate.

3. Are any Chapter 99 provisions actually duty-free?

Yes: 6 provisions begin with “Free” and another 5 specify a +0% additional duty. They are the exception — most of the subchapter's business is positive surcharges.

4. Why do some rows have no percentage at all?

386 provisions describe quota-period allocations or tariff-rate quotas in words rather than an “+X%” figure. We exclude them from the tier ladder and disclose the exclusion instead of imputing a rate.

5. Does the Chapter 99 surcharge stack on top of the normal duty?

Yes. The statutory wording is “the duty provided in the applicable subheading + X%”: the MFN rate applies first, then the additional duty. Resolve your 8-digit line and model the stack with a calculator before quoting.

6. How do I find the additional duty for my own HTS code?

Two routes: the official USTR Section 301 search takes an 8-digit subheading and returns the applicable action and rate, and ExportSonar's free HS/tariff lookup resolves the same Chapter 99 overlay directly from the code. Whichever route you use, write down the provision number itself — across this census the difference between neighboring provisions is often the whole margin.

Where to check next

• Section 301 line-exposure map
• highest US tariff lines
• Section 301 China primer
• duty calculator