How to Calculate U.S. Import Duty in 2026: Step by Step

U.S. import duty is calculated as: (customs value × HTS-specific base duty rate) + Section 122 surcharge (15% if applicable) + Section 232 stacks (steel, aluminum, copper, pharma) + Section 301 stacks (China-origin) + MPF (0.3464%, capped) + HMF (0.125% on ocean freight). USMCA-qualifying goods exempt from Section 122. The customs value is typically the transaction value – what you paid the supplier – adjusted by the rules in 19 CFR 152.

Calculating import duty looks simple – find the rate, multiply by the value – until you actually have to do it. The rate is rarely just one number; it is a base rate plus sectoral add-ons plus user fees, and the value is rarely just the invoice price.

This guide walks through the calculation in the order CBP performs it, with worked examples for three common importer profiles in 2026: an apparel SMB importing from Vietnam, a Tier 2 auto supplier importing from Germany, and a CPG importer running USMCA-qualifying goods from Mexico.

The duty calculation formula

CBP calculates the total duty owed on each entry by walking through six layers in order:

1. Determine the customs value (typically transaction value under 19 CFR 152.103).
2. Apply the HTS-specific base duty rate (Column 1, General; or Column 1, Special if a trade preference applies).
3. Apply Section 122 surcharge (15% ad valorem until July 24, 2026, unless USMCA-qualifying or Annex II excluded).
4. Apply Section 232 stack (steel, aluminum, copper, pharma after July 31). Generally not stacked on Section 122 – the importer pays Section 232 in lieu.
5. Apply Section 301 stack (China-origin goods, varies by HTS).
6. Add user fees: MPF (0.3464%, min $32.71, max $634.62 in 2026) and HMF (0.125% on ocean freight only).

Worked example 1: apparel from Vietnam (no FTA, full Section 122)

A women’s knit cotton T-shirt, HTS 6109.10.0040, imported from Vietnam, transaction value $4.00 per unit, 10,000 units shipped by ocean.

• Customs value: $40,000.
• Base duty (HTS 6109.10.0040, Column 1 General): 16.5% × $40,000 = $6,600.
• Section 122 surcharge: 15% × $40,000 = $6,000 (Vietnam is non-USMCA, no Section 232 coverage on apparel).
• Section 301: not applicable (Vietnam-origin, not China-origin).
• MPF: 0.3464% × $40,000 = $138.56.
• HMF: 0.125% × $40,000 = $50.
• Total duty + fees: $12,788.56. Effective rate: 31.97%.

Worked example 2: auto Tier 2 part from Germany (Section 232 in lieu of 122)

A finished steel bracket, HTS 7326.90.8688, imported from Germany, transaction value $250 per unit, 1,000 units shipped by ocean.

• Customs value: $250,000.
• Base duty (HTS 7326.90.8688, Column 1 General): 2.9% × $250,000 = $7,250.
• Section 232 (derivative steel): 25% × $250,000 = $62,500 (covered as steel derivative).
• Section 122 surcharge: NOT APPLIED – Section 232 governs and is not stacked.
• MPF: $634.62 (max cap reached at any value above ~$183k).
• HMF: 0.125% × $250,000 = $312.50.
• Total duty + fees: $70,697.12. Effective rate: 28.28%.

Worked example 3: USMCA-qualifying goods from Mexico (Section 122 exempt)

A finished kitchen appliance, HTS 8516.50.0080, imported from Mexico, transaction value $180 per unit, 5,000 units, USMCA-qualifying with valid certificate of origin.

• Customs value: $900,000.
• Base duty (HTS 8516.50.0080, Column 1 Special “S+” – USMCA): 0% × $900,000 = $0.
• Section 122 surcharge: NOT APPLIED – USMCA-qualifying goods are exempt.
• MPF: $634.62 (capped).
• HMF: 0.125% × $900,000 = $1,125 (if shipped by ocean; lower if by truck – HMF only on ocean cargo).
• Total duty + fees: $1,759.62. Effective rate: 0.20%.

How to determine customs value

Customs value is the dollar amount on which all the rates above are applied. The default is “transaction value” – what you paid the supplier, adjusted for specific items per 19 CFR 152.103.

• Add to the price paid: assists, royalties tied to the goods, packing costs, certain commissions paid by the buyer.
• Do not add: U.S.-side freight (post-port-of-entry), U.S. duty, U.S. taxes, post-import service fees.
• If transaction value cannot be determined (e.g., related-party transactions), CBP applies a hierarchy: identical goods, similar goods, deductive value, computed value.

User fees: MPF and HMF

Merchandise Processing Fee (MPF)

Charged on every formal entry (over $2,500). Rate: 0.3464% ad valorem. Minimum: $32.71 in 2026. Maximum: $634.62 (so any entry above ~$183k pays the cap).

MPF applies to imports from all origins and is not waived by trade agreements except specific FTA partners (USMCA, etc.) where the entry meets certain conditions.

Harbor Maintenance Fee (HMF)

Charged only on ocean freight. Rate: 0.125% of customs value. No min or max.

Air freight, truck, rail, courier – no HMF.

Frequently asked questions

How do I find my product’s HTS-specific duty rate?

Look up the 10-digit HTS code on the USITC HTSUS schedule (hts.usitc.gov). The Column 1 General rate is the MFN base. Footnotes show Section 232 / 301 / 122 add-ons. See our /what-is-hts-code/ guide for HTS lookup.

Does the Section 122 surcharge apply to my goods?

It applies to most imports unless the goods are (a) USMCA-qualifying with a valid Certificate of Origin, (b) covered by Annex II of the Section 122 proclamation, or (c) subject to Section 232 (which is not stacked on Section 122).

What is included in customs value?

Customs value is typically transaction value – the price actually paid plus assists, royalties tied to the goods, packing costs, and certain commissions. International freight is generally NOT included if the price is FOB; it IS included if the price is CIF or DDP. See 19 CFR 152.103 for the full rules.

Can I reduce my duty by changing how I value the goods?

Sometimes – via first-sale-for-export valuation, where you use the manufacturer-to-middleman price rather than the middleman-to-importer price. This requires careful documentation. See /customs-valuation-guide/.

Are there ways to legally reduce my duty rate?

Yes: tariff classification review (you may be using the wrong HTS), USMCA qualification, drawback (recover duty on exported goods), Foreign Trade Zone activation (defer duty), tariff engineering (modify product to fit a better-rated HTS). See /how-to-reduce-import-duties-complete-guide/.

How do user fees (MPF, HMF) work in the calculation?

MPF is 0.3464% of customs value, with a $32.71 minimum and $634.62 maximum per formal entry in 2026. HMF is 0.125% of customs value, ocean freight only, no min/max. Both are added after the duty calculation.