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 usually isn’t. The real number is a stack of measures layered on top of the base rate — and getting the stack wrong is the most common (and expensive) mistake 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 goods from China (commonly 7.5% or 25%), by HTS heading.
- Section 232 — duties on steel and aluminum (25%+), regardless of origin.
- IEEPA — country-level surcharges introduced in 2025.
- Reciprocal tariff — a baseline that applies broadly across origins.
- 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
- IEEPA: 20% → $200
- Reciprocal: 10% → $100
That’s 58.5% in duty — $585, not $35 — before the MPF and HMF fees. Change the origin to Vietnam and the 301 and IEEPA layers drop off; the number falls sharply. 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 stacks every measure 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 binding rulings, file CBP Form 19; for declarations, consult a licensed customs broker.