How US Import Duties Stack on Amazon FBA Products
US import duties aren't a single tax. They're layers that stack on top of each other. Here's how MFN duties, the Section 301 forced labor duties in force since 24 July 2026, the legacy China lists and Section 232 combine to eat your margin.
Most Amazon sellers who import products know they pay "duties." What they usually don't know is that duties aren't one number. They're three or four separate charges that stack on top of each other, and the total can be wildly different from what they expected.
We've run the numbers on hundreds of products through MarginStack's cost calculator, and the pattern is always the same. Sellers assume a single duty rate, maybe 10-15%, and the actual combined rate comes back at 40%, 60%, sometimes over 100%. The gap comes from not understanding how the layers work.
So here's how it actually breaks down.
The four duty layers
When your product arrives at a US port, it can face up to four separate tariff layers. Each one is calculated independently and added on top of the others. They don't compound (meaning the second layer isn't charged on the first layer's amount). They all apply to the same base: your declared customs value, which is usually your FOB cost.
Layer 1: MFN duty (the base rate). MFN stands for Most Favored Nation, which is a misleading name. It's just the standard duty rate that applies to imports from most countries. The rate depends entirely on your product's HS code (a 6-10 digit classification number). A silicone phone case might be 3.4%. A cotton t-shirt might be 16.5%. Steel pipe could be 0%. You look this up in the Harmonized Tariff Schedule at hts.usitc.gov.
Layer 2: Section 301 tariffs (China only). These were originally imposed in 2018-2019 during the US-China trade dispute and have been expanded several times since. They apply only to products originating from China, and they add 7.5% to 25% on top of the MFN rate, depending on which "list" your product falls under. There are four lists covering roughly 10,000 HS codes. If your product is on List 1, you're paying 25% extra. List 4A, 7.5%. Your HS code determines which list applies. We wrote a deeper breakdown of how Section 301 lists work and what they cost if you want the full picture.
Layer 3: Section 301 forced labor duties (60 economies). This is the newest layer, effective 12:01 a.m. eastern time on July 24, 2026. It replaced the Section 122 global surcharge, which ran at 10% from February 24, 2026 and expired the same minute this took effect. The rate is a flat 10% for 17 economies including India, Indonesia, Malaysia, Cambodia, Bangladesh, Mexico, Canada and the United Kingdom, and a flat 12.5% for 38 economies including China, Vietnam and Brazil. For the European Union and Taiwan it is capped so MFN plus this duty reach 10% together, and for Japan, Korea and Switzerland so they reach 12.5% together. It does not apply where a Section 232 duty applies to the same line, where goods enter duty free under USMCA, or on a chapter 98 entry. If you source from Vietnam or India to dodge China-specific tariffs, this duty applies to those imports too. We wrote a detailed analysis of the SCOTUS ruling and its consequences if you want the full picture.
Layer 4: Section 232 tariffs (metals and certain other goods). If your product is made of steel, aluminum or copper, or contains significant amounts of any of them, a national security tariff applies. The rate depends on which annex the article falls in and has changed several times since 2018, so look yours up rather than assuming a single number. Since April 6, 2026 the duty applies to the full customs value of a covered article, not just its metal content. It applies regardless of country of origin, though some trade agreements provide exemptions.
How stacking works in practice
Let's take a real example. A silicone kitchen spatula sourced from China.
The HS code for this product carries a 3.4% MFN rate. It is on Section 301 List 3 at 25%. And since July 24, 2026 the Section 301 forced labor duty applies to China-origin goods at 12.5%.
On a $6.00 FOB cost per unit:
- MFN duty: $6.00 x 3.4% = $0.20
- Section 301: $6.00 x 25% = $1.50
- Section 301 forced labor: $6.00 x 12.5% = $0.75
- Total duties: $2.60 per unit (43.4% effective rate)
That 3.4% "duty rate" a seller might find by Googling their HS code? Since July 24, 2026 it is actually 40.9% when all layers stack. And before the Supreme Court struck down IEEPA tariffs on Feb 20, 2026, it was higher still. Before the SCOTUS ruling, certain product categories sourced from China faced cumulative tariffs exceeding 145% when all IEEPA layers combined. One seller importing mid-range consumer electronics had faced an effective total tariff rate over 145% under the old regime. Even with IEEPA gone, their combined rate (MFN plus the legacy Section 301 list plus the forced labor duty) still makes the product unviable in a competitive category.
The HS code is everything
Every layer above depends on your HS code. Get the code wrong and every duty calculation downstream is wrong too.
This happens more often than you'd think. One seller documented how their freight carrier classified imported automotive replacement parts under a "plated household goods" code, triggering an 8.5% duty rate instead of the correct 2.5%. That's a 240% increase in duty costs from a single classification error. When the seller tried to dispute it, the carrier charged an additional $90 "research fee" to review the classification.
The catch-all problem makes it worse. When customs can't determine the correct HS code from the shipping paperwork, they classify the product into the "Other" category for that product group. The "Other" category almost always carries the highest possible duty rate. One seller importing decorative ceramic items found their shipment classified under "Other articles of porcelain" at 9% instead of the correct "ornamental articles" code at 0%. Nine percent of declared value on a full container adds up fast, especially when you don't notice for months.
US Customs and Border Protection's own website acknowledges this: "Experts spend years learning how to properly classify an item in order to determine its correct duty rate." They give the example of a wool suit where the duty rate depends on whether it has darts, where the wool came from, where the suit was assembled, and whether the lining contains synthetic fibers.
We wrote a full walkthrough of how to look up your HS code if you want to verify yours.
For a detailed breakdown of how each duty layer works and how they interact, check out the MarginStack Duty Stack Explainer.
Why this matters more than Amazon fees
Here's something that surprises most sellers when they run the full numbers. A mid-volume seller ran their complete cost waterfall for the first time and discovered that import costs (freight + duties + brokerage) often rival or exceed Amazon's combined fees on imported products. On a $29.99 product, Amazon fees totaled $8.90 (29.7% of selling price) while total import costs came to $5.40 (18%). The seller had spent months obsessing over Amazon's fees while the tariff stack was the cost center they'd accepted without question, mostly because they didn't know the actual rate.
The difference between knowing your duty rate and guessing is the difference between a product that makes money and one that quietly bleeds cash. Especially now, with tariff rates changing faster than most sellers update their spreadsheets.
What to do about it
Three things, in order of impact:
Verify your HS code. Don't trust whatever your freight forwarder or supplier put on the commercial invoice. Look it up yourself at hts.usitc.gov, or use MarginStack's calculator which pulls rates directly from the USITC database. If the rate seems wrong, check the CBP CROSS rulings database for similar products.
Model the full stack, not just the base rate. A product with a 3.4% MFN rate sounds cheap to import. A product with a 40.9% combined rate after the legacy Section 301 list and the forced labor duty? That changes your entire pricing model. Run the full cost waterfall before committing to inventory.
Compare sourcing countries. The legacy Section 301 lists only apply to China-origin goods. The forced labor duty applies to 60 economies, but on its own it is less punishing than the combined legacy list plus forced labor stack that China-origin goods face. The same product sourced from Vietnam, India, or Mexico avoids the legacy lists entirely. Even if the FOB cost is 15-20% higher, the tariff savings can more than make up the difference. MarginStack's country comparison tool shows you that math side by side.
Tariff stacking is not going away. The Supreme Court struck down one layer (IEEPA) and it was replaced within hours by Section 122, which itself expired in July 2026 and was replaced the same minute by the Section 301 forced labor duties. The legal basis changes, but the cost impact on your margins persists. The sellers who understand exactly what they're paying, layer by layer, are the ones making informed sourcing decisions. Everyone else is guessing.