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Section 301 China Tariff Calculator: How to Stack the 25% Surcharge Correctly

Two official datasets feed this page, each stamped with its own date: the Harmonized Tariff Schedule base rates come from the 23,193-line USITC export generated 2026-10-19, and the Section 301 action mapping comes from a separate USITC Chapter 99 REST pull captured 2026-10-16 (its source PDF integrity-pinned by SHA-256 in our data registry). Every figure below is recomputed from both at generation time.

Search engines are full of pages promising a "Section 301 calculator", and most deliver a single input box that multiplies value times 25 percent - wrong whenever your line has a nonzero base rate, wrong when your line carries a compound rate, and always silent about the fee floor. This page shows the actual stacking arithmetic, names the exact Chapter 99 headings the action lives in, and links each step to a working tool.

What stacking means: base rate plus Chapter 99 action

The Section 301 China action is a flat 25% ad-valorem surcharge defined in Chapter 99 heading 9903.88, applied on top of the Column 1 (MFN) general rate. For ad-valorem base rates the two percentages simply add, because both act on the same customs value:

effective % = MFN general % + 25.0%   (China-origin, mapped lines)

A Free base line goes straight to 25%. A 6.5% base line pays 31.5%. The subtlety is compound bases: a line paying "15.4¢/kg + 6.5%" converts the per-kilogram leg to dollars at your declared quantity first, and the 25% surcharge applies to the value portion - our specific-and-compound guide walks that conversion with census numbers. And unlike duty, the Merchandise Processing Fee (0.3464%, FY2027 minimum $34.58) and Harbor Maintenance Fee (0.125%, ocean entries) apply even when the stacked duty rate itself would be zero.

Which HTS lines carry the action today?

In the current extract the action enumerates 7,045 unique eight-digit HTS lines across three active action headings, all at exactly 25.0%:

Source: USITC Chapter 99 REST export parsed at generation time; 62 anchor provisions parsed, 47 skipped as out-of-scope, 1,069 deferred-tranche rows enumerated separately.

Coverage is uneven by design: machinery and electronics chapters 84-85 are heavily mapped, while consumer goods such as knit apparel (chapter 61) carry zero mapped lines in this extract. Check your exact code instead of assuming - the HS code browser resolves membership per line.

Run the numbers yourself, step by step

1. Open the landed-cost duty calculator.
2. Enter your ten-digit HTS number - paste it exactly; statistical suffixes matter for filing even when the rate repeats (our ten-digit suffix guide explains why).
3. Set origin country to China so the Chapter 99 layer engages.
4. Read the stacked estimate: base rate, Section 301 layer, MPF/HMF fees, dollar total.
5. Screen for antidumping/countervailing duties on top - the AD/CVD case lookup covers 211 recent cases a 301 surcharge does not absorb.
6. Log the date and figures; exclusion windows move, so a screenshot is not a quote.

Worked examples at $10,000 declared value

The two real lines were checked against the live schedule and the Chapter 99 action mapping at generation time; the third row is an illustration, not a schedule entry.

Exclusion windows and deferred tranches

Beyond the three active headings, the extract enumerates 1,069 deferred-tranche rows spread over twelve headings in the 9903.90/91 range - lines whose action status depends on effective-date windows rather than current coverage. Treat any landed-cost model that ignores expiry dates as a dated assumption: an expired exclusion sends affected lines back to the full action rate, and the difference between 7.5% and 25% on a container-sized order usually dwarfs the margin the sale was priced on.

Three mistakes that turn a correct rate into an incorrect invoice

• Quoting the 301 rate alone. Buyers see "25%" and budget 25% - then discover their line also owed a 16.5% base rate or a specific-duty leg. Always quote the stacked number.
• Applying the action by brand, not origin. The statute keys on country of origin. A Chinese-brand product manufactured in Thailand is outside the action; a US-brand product made in China is inside it.
• Ignoring the fee floor on Free lines. Half the drama in machinery chapters happens at zero duty: the MPF minimum and HMF still apply, and remedy screening comes next.

Where the fee floor comes from

Duty is only part of the entry bill. Two user-fee programs apply regardless of the duty rate, including on lines that enter Free: the Merchandise Processing Fee, assessed at 0.3464% of entered value with a FY2027 minimum of $34.58 per formal entry, and the Harbor Maintenance Fee, 0.125% on ocean entries with no minimum. On small orders these fees exceed the duty itself; on large ones they are rounding errors, but a quote that forgets them is still an inaccurate quote. Our MPF/HMF guide breaks out the admissible reductions and exemptions, and the calculator itemizes both automatically.

What a Section 301 calculator cannot do for you

Honest limits, stated plainly: a static calculator cannot determine country of origin for goods with manufacturing steps in several countries; it cannot rule on whether your product's specifications fall inside a provision's scope language; and it cannot price remedy layers such as antidumping or countervailing duties, which attach to specific producers and scopes rather than to tariff lines. What it can do - and what our tooling does live - is resolve the statutory rate layers exactly, so the human judgment you spend time on is spent on the questions that actually require it. For the classification step that precedes any rate lookup, see our machinery-parts stacking map for how thirty high-traffic headings behave under the full stack.

Frequently asked questions

Is there an online calculator for Section 301 China tariffs by HTS number?

Yes. ExportSonar's free landed-cost calculator lets you enter a ten-digit HTS number, a customs value and China as origin, then stacks the MFN base rate with the Chapter 99 Section 301 layer automatically. In the October 2026 extract every one of the 7,045 mapped eight-digit lines carries exactly 25.0 percent, so the arithmetic is transparent - but the tool also itemizes MPF and HMF entry fees, which a plain percentage calculation forgets.

How do I stack Section 301 rates on top of the MFN rate?

For ad-valorem base rates the layers add arithmetically: a line with a 4.4% MFN rate pays 29.4% once the flat 25% Section 301 action applies, because both percentages act on the same customs value. Lines whose base rate is Free go straight to 25%. Compound bases (cents per kilogram plus percent) need the specific leg converted to dollars first, then the 25% applies on the value only. Merchandise Processing Fee and Harbor Maintenance Fee are added regardless of duty: on a $1,000 entry that is the $34.58 FY2027 MPF minimum plus $1.25 of HMF.

Do any HTS chapters still carry the older 7.5% List 4A rate?

None among currently mapped lines. In the October 2026 Chapter 99 export all 7,045 China-origin eight-digit lines mapped to the three active action headings (9903.88.01/02/03) carry exactly 25.0%. If your source quotes 7.5%, it is repeating an outdated snapshot from an earlier exclusion window - re-price against today's schedule or our live lookup before you commit to a selling price.

Does Section 301 still apply if I ship through Vietnam or Mexico?

Usually yes, because the measure follows country of origin, not country of shipment. Goods substantially transformed in a third country can acquire that origin, but mere transshipment or repacking does not change it - CBP assesses origin under its own rules case by case. Also note that FTA preference claims clear only the base-schedule Special column; they never waive a Chapter 99 add-on such as the Section 301 action.