How Section 301 and stacked tariffs affect cost per unit

What "stacking" means

Every imported product has a base duty rate in the Harmonized Tariff Schedule, called the MFN (most-favored-nation) rate. On top of that, other programs can add their own tariffs. When more than one applies to the same product, they are entered as separate lines and added together. We call that the tariff stack.

The layers you're most likely to see in 2026:

• Base (MFN) duty. Set by the HTS code. Often 0% to 15%.
• Section 301 (China). In place since 2018. Most goods on Lists 1 to 3 pay 25% and List 4A pays 7.5%, with higher rates on some strategic products after the 2024 review.
• Section 301 forced-labor tariff. In effect since July 24, 2026, at 10% or 12.5% depending on the country of origin. China is in the 12.5% tier.
• Section 232. Tariffs on steel, aluminum, copper, and some other goods, including the metal content of many finished products.
• Antidumping and countervailing duties. Specific to certain products from certain countries.

Not every pair of layers applies together. The clearest example: goods subject to Section 232 are excluded from the forced-labor tariff, so a steel or aluminum product pays Section 232 but not the 10% or 12.5% forced-labor tier. China's original Section 301 tariffs can still apply on top of Section 232. Other exclusions come and go, so your customs broker can tell you exactly which layers your HTS code and origin pay.

The math: add the rates, apply to goods value

Each layer is a percentage of the same customs value (the goods value, not freight). So you can add the rates first and apply the total once:

Take a product that costs $18.75 FOB from China, with 3.9% base duty, 25% Section 301, and the 12.5% forced-labor tier:

The base duty, the number many sellers look up, is less than a tenth of the total.

What each layer does to your margin

Here's the same product shipped 600 units by ocean, with $6.42 per unit in freight and other charges, sold at $79.99 with 15% channel fees and $9.50 fulfillment:

The two added layers took $7.04 out of every unit's profit and almost nine points of margin. To keep a 30% margin at the full stack, the price needs to be at least $77.30, up from $64.52 with base duty alone.

Why rates need an as-of date

Tariffs changed several times in 2026 alone. In February, the Supreme Court ruled that IEEPA does not authorize tariffs, and CBP began processing refunds. A temporary 10% Section 122 tariff took effect on February 24 and expired on July 24, the same day the forced-labor tier began. Exclusions on specific products also expire on fixed dates.

So treat every rate as "true as of the day you checked it." Write the date next to it, and recheck before each order, not just once a year.

Planning for the next change

• Enter each layer separately. A single blended rate hides which program changed when your duty bill jumps.
• Run a what-if before you order. Ask what your margin looks like if a layer rises or falls 10 points.
• Stage price increases. If a new layer lands mid-season, raising prices in steps can protect margin without shocking customers.
• Compare origins on landed cost. A supplier with a higher price in a lower-tariff country can come out cheaper per unit.

Tariff rates, lists, and stacking rules change often. Dock & Dollar does not classify products or look up rates. This guide is for planning only and is not customs, legal, or tax advice. Confirm HTS codes and tariff rates with a licensed customs broker.