Import duties are one of the biggest variable costs in international trade. Understanding how they're calculated — and how to legally minimize them — can dramatically affect your landed cost and competitive position.
Import duties (also called customs duties or tariffs) are taxes levied by the US government on goods entering the country. They're collected by US Customs and Border Protection (CBP) at the time of entry. Duties serve two purposes: revenue generation and trade policy (protecting domestic industries).
Duties are distinct from other import costs:
• Duty: Tax on the value/quantity of the imported good
• Merchandise Processing Fee (MPF): CBP's administrative fee (0.3464% of value, min $31.67, max $614.35 per entry)
• Harbor Maintenance Fee (HMF): 0.125% of cargo value for sea shipments
• Other fees: FDA filing, anti-dumping/countervailing duties, Section 301 tariffs
The duty rate is determined entirely by the HTS code of the product.
Ad Valorem duties — the most common type. Expressed as a percentage of the customs value of the goods. Example: 5% ad valorem on $10,000 of goods = $500 duty.
Specific duties — charged per unit of measurement regardless of value. Example: "$0.15 per kilogram" or "$0.50 per liter." Common for agricultural products, chemicals, and commodities.
Compound duties — a combination of both. Example: "6.3% + $1.40/kg." The percentage applies to the value and the specific duty applies per unit.
Temporary duties:
• Section 201 (global safeguard) duties — protect US industries from surges in imports
• Section 232 (national security) duties — currently apply to steel (25%) and aluminum (10%) from most countries
• Section 301 (China retaliation) — additional 7.5%–100% on thousands of Chinese-origin HTS codes
Step 1: Get the correct HTS code
Duty rates are HTS-code specific. A wrong code gives you the wrong rate.
Step 2: Determine the customs value
The US uses the transaction value method (WTO Customs Valuation Agreement) — the price actually paid or payable for the goods. Add any assists (tooling, IP, etc.) and deductions for international freight and insurance if included in the price.
Step 3: Find the duty rate
At hts.usitc.gov, look up your 10-digit HTS code. The Column 1 rate is your standard rate. Check the Special column for any applicable FTA rates (USMCA, etc.).
Step 4: Calculate base duty
For ad valorem: Customs value × duty rate %
For specific: Quantity × rate per unit
Step 5: Add Section 301 tariffs if applicable
If your goods are from China (or origin-shifted Chinese goods), check whether your HTS code appears on any of the four Section 301 lists. If so, add the additional duty rate.
Step 6: Add MPF and HMF
MPF: 0.3464% of customs value (min $31.67, max $614.35)
HMF (ocean shipments only): 0.125% of customs value
Example calculation:
Product: Laptop computers (HTS 8471.30.0100)
Customs value: $50,000
Base duty rate: Free (0%)
Section 301: Not applicable (laptops excluded)
MPF: $50,000 × 0.3464% = $173.20
Total: $173.20
The customs value isn't always just the invoice price. CBP uses the following hierarchy:
1. Transaction value — the price paid/payable + assists + other additions. This is used for ~95% of entries.
2. Transaction value of identical goods — if #1 can't be determined
3. Transaction value of similar goods
4. Deductive value — based on resale price in the US minus deductions
5. Computed value — based on production cost plus profit
6. Fall-back method — flexible application of prior methods
What gets added to transaction value:
• Packing costs (if not already included)
• Selling commissions (buying commissions are not dutiable)
• Assists: tooling, molds, materials, or IP provided to the foreign supplier
• Royalties/license fees related to the imported goods
What gets excluded:
• International shipping and insurance (if separately stated on invoice)
• US customs duties themselves
1. Leverage Free Trade Agreements
USMCA (Canada/Mexico), KORUS (South Korea), US-Singapore FTA, and 12 other US FTAs can reduce or eliminate duties for qualifying goods. You must document origin and file a certification of origin.
2. First Sale Valuation
If goods are sold through an intermediary, you may be able to use the "first sale" price (manufacturer → middleman) rather than the final sale price (middleman → you) as the customs value — potentially reducing the dutiable value significantly.
3. Foreign Trade Zones (FTZs)
FTZs are designated areas where goods can be manufactured, processed, or stored without paying duty until they enter US commerce. Useful for manufacturers who import components and export finished goods.
4. Bonded Warehouses
Imported goods can be stored in a bonded warehouse for up to 5 years without paying duties. Pay duties only when you withdraw goods for US consumption — or re-export them duty-free.
5. Duty Drawback
If you import goods, use them in manufacturing, and then export the finished product, you can reclaim up to 99% of the duties paid on the imported inputs.
6. Section 301 Exclusion Requests
CBP periodically accepts exclusion requests for specific products from Section 301 China tariffs. Check USTR.gov for active exclusion opportunities.
• Relying on the importer of record's estimate: Get the exact rate from hts.usitc.gov for your specific 10-digit code — don't use general industry estimates.
• Forgetting Section 301 tariffs: The base HTS rate may be 0%, but if the goods are from China and the HTS code is on a Section 301 list, you owe additional duties. Both must be calculated.
• Missing MPF caps: MPF has a per-entry maximum of $614.35 for formal entries. Large consolidated shipments benefit disproportionately from this cap.
• Not accounting for anti-dumping/countervailing duties (AD/CVD): Certain steel, aluminum, solar, and other products face separate AD/CVD orders that can add 100%+ to the duty burden. Check CBP's AD/CVD search.
• Undervaluing goods: CBP has extensive intelligence on global pricing. Undervaluation is one of the most-audited areas and carries severe fraud penalties.
Real US CBP manifest data for freight brokers and importers
In the US, the importer of record (IOR) is legally responsible for paying import duties to CBP. In most commercial import transactions, that's the US buyer. However, trade terms (Incoterms) affect who bears the economic burden — under DDP (Delivered Duty Paid), the seller covers duties; under DAP or EXW, the buyer does. The legal liability to CBP always falls on the IOR.
No. Import duties are federal taxes collected by CBP at the border, based on the customs value and HTS code. Sales tax is a state/local tax collected at point of sale to the end consumer. They're separate taxes levied by different authorities at different points in the supply chain. You may owe both on imported goods that are sold domestically.
Look up your 10-digit HTS code in the current USTR Section 301 tariff lists (published at ustr.gov). There are four "lists" (List 1, 2, 3, 4A) covering different categories of Chinese-origin goods with rates of 7.5%, 10%, 25%, or higher. Also check hts.usitc.gov under Chapter 99, Subchapter III for current Section 301 codes and their rates.
Yes, through a CBP protest (CBP Form 19). You have 180 days from the date of liquidation of your entry to file a protest claiming a refund. Common reasons include using the wrong HTS code, incorrect customs valuation, or failure to claim an applicable FTA rate. If the protest is denied, you can appeal to the Court of International Trade.
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