How Tariff Stacking Works and How to Calculate Your Total Duty

How Does Tariff Stacking Work in the U.S.?

Tariff stacking occurs when multiple tariff authorities apply to the same imported product. A single shipment can be subject to the MFN base duty, a Section 232 national security tariff, a Section 301 unfair trade practice tariff, and the Section 122 global surcharge, each calculated on the same customs value and added together. The key to accurate duty calculation is knowing which layers apply and which layers are mutually exclusive.

How Do You Calculate Total Import Duty with Multiple Tariff Layers?

Start with your product's MFN base rate, then check for Section 232 coverage (steel, aluminum, autos, copper, lumber, semiconductors), then Section 301 (Chinese-origin goods only), then Section 122 (10% surcharge on most goods not covered by Section 232). Add the Merchandise Processing Fee (0.3464%) and Harbor Maintenance Fee (0.125% for ocean shipments). The total of all applicable layers is your customs duty obligation.

The concept is straightforward, but the stacking rules create real complexity. Not all layers stack with each other. Section 232 and Section 122 are mutually exclusive: if Section 232 applies, Section 122 does not. Section 301 stacks with everything except products on the suspended List 4B. AD/CVD duties stack on top of all other layers.

This guide walks through the stacking hierarchy and provides three complete worked examples with real numbers: Chinese consumer electronics, Canadian steel, and Vietnamese textiles.

Last updated: March 2026

For a conceptual overview of tariff stacking (what it is and why it matters), see our published guide: How Tariff Stacking Works: Section 232, Section 301, Section 122, and Chapter 99. This article is the "how to calculate" companion.

The Stacking Hierarchy

Understanding which tariff layers stack and which take primacy is the foundation of accurate duty calculation.

Layers That Always Apply

Layer	Rate	Basis
MFN base duty	Varies by HTS code	Applied to all imports based on product classification
MPF	0.3464% (min $31.67, max $614.35)	Applied to all formal entries
HMF	0.125%	Ocean freight only

Layers That Apply Conditionally

Layer	When It Applies	When It Does NOT Apply
Section 232	Product is steel, aluminum, auto, copper, lumber, or semiconductor	Does not apply if product is not in a covered category
Section 301	Product is Chinese-origin and on Lists 1, 2, 3, or 4A	Does not apply to non-Chinese goods or suspended List 4B products
Section 122	Product is not covered by Section 232, and not USMCA-qualifying	Does not apply if Section 232 covers the product, or if USMCA preference is claimed
AD/CVD	Specific product from specific country under active AD/CVD order	Does not apply unless there is an active order

The Primacy Rule

Section 232 takes primacy over Section 122. If a product is subject to a Section 232 tariff, the Section 122 surcharge does not apply to the portion covered by Section 232. For derivative products (e.g., a finished good containing steel or aluminum), Section 232 applies to the metal content, and Section 122 applies to the remaining value.

Section 301 stacks with Section 232. A Chinese steel product faces both Section 232 (50% on steel) and Section 301 (25% on Chinese-origin goods). They are additive.

Section 301 stacks with Section 122. A Chinese consumer product faces both Section 301 (7.5% or 25%) and Section 122 (10%).

GingerControl's Tariff Calculator handles all stacking rules automatically. Enter your HTS code and country of origin, and the calculator applies the correct hierarchy.

Worked Example A: Chinese Consumer Electronics

Product: Wireless Bluetooth speakers (HTS 8518.22.00) Country of origin: China Declared customs value (FOB): $75,000 Shipping mode: Ocean freight

Step 1: Identify MFN base rate HTS 8518.22.00 (loudspeakers, multiple, mounted in same enclosure): MFN rate = 4.9%

Step 2: Check Section 232 This product is not steel, aluminum, auto, copper, lumber, or semiconductor. Section 232 does not apply.

Step 3: Check Section 301 HTS 8518.22.00 is on Section 301 List 1. Rate = 25%.

Step 4: Check Section 122 Since Section 232 does not apply, Section 122 applies. Rate = 10%.

Step 5: Check AD/CVD No active AD/CVD order on this product from China. AD/CVD = $0.

Step 6: Calculate

Duty Layer	Rate	Calculation	Amount
MFN base duty	4.9%	$75,000 x 4.9%	$3,675.00
Section 301 (List 1)	25%	$75,000 x 25%	$18,750.00
Section 122	10%	$75,000 x 10%	$7,500.00
Subtotal duties			$29,925.00
MPF	0.3464%	$75,000 x 0.3464%	$259.80
HMF	0.125%	$75,000 x 0.125%	$93.75
Total duties and fees			$30,278.55
Effective duty rate			40.4%

The $75,000 shipment generates over $30,000 in duties and fees. The Section 301 tariff alone ($18,750) exceeds five times the MFN base duty ($3,675).

Worked Example B: Canadian Steel

Product: Steel pipe, welded (HTS 7306.30.50) Country of origin: Canada Declared customs value (FOB): $120,000 Shipping mode: Ocean freight USMCA status: Not applicable (Section 232 overrides USMCA for steel)

Step 1: Identify MFN base rate HTS 7306.30.50 (other tubes, pipes, welded, of iron or nonalloy steel): MFN rate = 0%

Step 2: Check Section 232 Steel product. Section 232 applies at 50%.

Step 3: Check Section 301 Country of origin is Canada, not China. Section 301 does not apply.

Step 4: Check Section 122 Section 232 takes primacy. Section 122 does not apply.

Step 5: Check AD/CVD Canadian welded steel pipe is subject to an active antidumping duty order. Assume AD rate of 15.63% (rates vary by manufacturer; this is illustrative).

Step 6: Calculate

Duty Layer	Rate	Calculation	Amount
MFN base duty	0%	$120,000 x 0%	$0.00
Section 232 (steel)	50%	$120,000 x 50%	$60,000.00
Section 301	N/A (not China)		$0.00
Section 122	N/A (Section 232 primacy)		$0.00
AD duty	15.63% (illustrative)	$120,000 x 15.63%	$18,756.00
Subtotal duties			$78,756.00
MPF	0.3464%	$120,000 x 0.3464%	$415.68
HMF	0.125%	$120,000 x 0.125%	$150.00
Total duties and fees			$79,321.68
Effective duty rate			66.1%

The effective rate exceeds 66%. The Section 232 tariff ($60,000) is the dominant cost. USMCA qualification would not help here because Section 232 applies to steel regardless of USMCA status. Note that AD/CVD rates are company-specific; importers must verify the applicable rate for their specific supplier.

Worked Example C: Vietnamese Textiles

Product: Cotton knit T-shirts (HTS 6109.10.00) Country of origin: Vietnam Declared customs value (FOB): $40,000 Shipping mode: Ocean freight

Step 1: Identify MFN base rate HTS 6109.10.00 (T-shirts, singlets, tank tops, of cotton, knitted): MFN rate = 16.5%

Step 2: Check Section 232 This product is not steel, aluminum, auto, copper, lumber, or semiconductor. Section 232 does not apply.

Step 3: Check Section 301 Country of origin is Vietnam, not China. Section 301 does not apply.

Step 4: Check Section 122 Since Section 232 does not apply, Section 122 applies. Rate = 10%.

Step 5: Check AD/CVD No active AD/CVD order on cotton T-shirts from Vietnam. AD/CVD = $0.

Step 6: Calculate

Duty Layer	Rate	Calculation	Amount
MFN base duty	16.5%	$40,000 x 16.5%	$6,600.00
Section 301	N/A (not China)		$0.00
Section 122	10%	$40,000 x 10%	$4,000.00
Subtotal duties			$10,600.00
MPF	0.3464%	$40,000 x 0.3464%	$138.56
HMF	0.125%	$40,000 x 0.125%	$50.00
Total duties and fees			$10,788.56
Effective duty rate			27.0%

The same T-shirts from China would face an additional 7.5% Section 301 tariff (List 4A), bringing the effective rate to approximately 34.5%. The 7.5 percentage point difference illustrates why many apparel importers have diversified sourcing from China to Vietnam, despite Vietnam now facing the Section 122 surcharge.

GingerControl is a trade compliance AI platform that helps importers, exporters, and customs brokers classify products, simulate tariff costs, and track policy changes. The Tariff Calculator handles all stacking rules and shows every duty component across 200+ countries.

Comparing All Three Examples

	Chinese Electronics	Canadian Steel	Vietnamese Textiles
FOB Value	$75,000	$120,000	$40,000
MFN Rate	4.9%	0%	16.5%
Section 232	N/A	50%	N/A
Section 301	25%	N/A	N/A
Section 122	10%	N/A (232 primacy)	10%
AD/CVD	None	15.63%	None
Total Duties	$29,925	$78,756	$10,600
Effective Rate	40.4%	66.1%	27.0%

The variation is enormous. A product's effective tariff rate depends not just on the product itself, but on the country of origin and which tariff authorities apply. The same product from different countries can face dramatically different duty levels.

FAQ

Do all tariff layers stack on top of each other?

No. Section 232 and Section 122 are mutually exclusive: if Section 232 applies, Section 122 does not. Section 301 stacks with both Section 232 and Section 122. AD/CVD duties stack on top of everything. MFN base duty always applies. The stacking rules create different effective rates depending on the product and country combination.

How do I calculate duties on a derivative product (e.g., a finished good containing steel)?

For steel or aluminum derivative products, the 50% Section 232 tariff applies to the steel/aluminum content value, and the applicable reciprocal tariff (Section 122 at 10%) applies to the remaining value. You need to determine the metal content percentage to calculate the duty correctly.

What happens to tariff stacking when Section 122 expires in July 2026?

If Section 122 expires without replacement, the Section 122 layer drops from all calculations. Products covered by Section 232 or Section 301 would still face those tariffs. Products from non-China countries not covered by Section 232 would revert to MFN-only rates, a significant reduction. However, the administration's Section 301 investigations could produce country-specific tariffs before or shortly after expiration.

Can I reduce my tariff stack?

Several strategies can lower the total duty: source from countries with lower tariff exposure (e.g., Vietnam instead of China for non-Section 232 goods), qualify for USMCA preferences (eliminates Section 122), apply for Section 301 exclusions, utilize Foreign Trade Zones (FTZs) for tariff deferral or inversion, and claim duty drawback on re-exported goods.

Does GingerControl calculate the full tariff stack automatically?

Yes. GingerControl's Tariff Calculator applies all stacking rules based on your HTS code and country of origin. It shows each duty layer separately with a transparent breakdown, so you can see exactly which authorities apply and at what rate.

Calculate Your Total Duty Stack

Tariff stacking makes duty calculation complex, but it does not have to be a guessing game. GingerControl's Tariff Calculator covers every layer of the current U.S. tariff system: MFN, Section 232, Section 301, Section 122, and AD/CVD, with automatic stacking rules and transparent breakdowns for 200+ countries. Try it free →

GingerControl is not just a tool. We work with importers and trade compliance teams on process consulting, digital transformation strategy, and end-to-end custom system development. Talk to our team →

References

[REF 1] White House — Section 122 Fact Sheet Data cited: 10% surcharge, Section 232 primacy, USMCA exemption, 150-day expiration Source: White House Published: February 20, 2026

[REF 2] Global Trade Alert — US Tariff Stacking Explained Data cited: Stacking hierarchy, derivative product rules, Section 232 primacy over Section 122 Source: Global Trade Alert Published: 2025

[REF 3] CBP — Section 232 Steel and Aluminum FAQs Data cited: Steel/aluminum at 50%, derivative stacking procedure, HTS classifications Source: CBP Published: Current

[REF 4] USTR — Section 301 Tariff Actions Data cited: List 1-4A rates, product coverage by HTS code Source: USTR Published: Current

[REF 5] White & Case — Section 122 Tariff Analysis Data cited: Section 122 structure, interaction with bilateral deals, Annex II exceptions Source: White & Case Published: February 2026

[REF 6] Yale Budget Lab — State of Tariffs: March 9, 2026 Data cited: Overall effective tariff rate under Section 122 Source: Yale Budget Lab Published: March 9, 2026