Tariff stacking explained: why your duty is higher than the base rate
Last updated: 2026-06-02
If you look up a product in the tariff schedule and see “3.5%,” it’s tempting to assume that’s the duty. Since 2024 it often isn’t. The real number is a stack of measures layered on top of the base rate — and getting the stack wrong is one of the most expensive mistakes importers make right now.
The layers
A US import duty can include any of these, each applied to the customs value:
- Base / MFN rate — the rate in the Harmonized Tariff Schedule for the code. The floor.
- Section 301 — extra duties on many goods from China (commonly 7.5% or 25%), by HTS line and product list.
- Section 232 — duties on steel, aluminum, copper and listed derivatives. Core articles can be 50%; some derivatives are content-based.
- Temporary import surcharge — the current Section 122 broad-origin surcharge, 10% from February 24, 2026 through July 24, 2026 unless changed.
- Former IEEPA / reciprocal tariffs — 2025-era country-level actions that ended effective February 20, 2026. They still matter for historical entries, not as a default current layer.
- AD/CVD — anti-dumping / countervailing duties on specific products and exporters.
- MPF and HMF — the Merchandise Processing Fee (with a min and max) and Harbor Maintenance Fee.
A worked example
Take a flashlight (HTS 8513.10.20.00) imported from China at a $1,000 customs value:
- Base MFN: 3.5% → $35
- Section 301: 25% → $250
- Temporary import surcharge: 10% → $100
That’s 38.5% in duty — $385, not $35 — before the MPF and HMF fees. Change the origin to Vietnam and the China-specific Section 301 layer drops off, but the temporary import surcharge may still apply unless an exemption or preference covers the entry. Origin changes the stack, which is why a single “rate” is meaningless without it.
See it for your product
Don’t compute this by hand. Use the tariff & duty calculator — enter the HTS code, origin and value and it estimates the measures in force on today’s date. Not sure of the code? Start with the HTS code lookup, or browse duties by country. For the all-in number including freight, use the landed-cost calculator.
Informational only — not customs advice. Classification and valuation decisions are the importer’s responsibility under 19 USC §1484. For declarations or binding rulings, consult a licensed customs broker.