1 · Classification
Start with the US HTS code, not the supplier's tariff percentage
USTR's Section 301 product search is keyed to HTS subheadings, and the ordinary US duty rate also comes from the HTSUS. A six-digit international HS code can be too broad for a US entry, so TariffCalc's exact-code workflow uses the published US schedule.
2 · Country of origin
“Shipped from” and “originating in” are not interchangeable
Country of origin is a customs-law question tied to where an article was manufactured, produced or grown and, in some situations, whether later processing creates a substantial transformation. Routing Chinese-origin goods through another country does not by itself establish a new origin.
For a material entry, confirm origin on the actual production facts. TariffCalc accepts the origin as an input; it does not make a binding origin ruling.
3 · Section 301
China Section 301 is product-specific
USTR identifies affected products by HTS subheading and publishes the applicable action/modification information. TariffCalc applies only versioned, supported Chapter 99 references from its registry; an unknown, excluded or overlapping case becomes review required instead of being silently treated as zero.
24 active supported/review registry rows are currently loaded for the 9903.88/9903.91 families.
Review Section 301 coverage4 · Section 232
Some China-origin steel can have a separate Section 232 component
The current TariffCalc beta automates only its locked Phase 25 China-origin primary-steel Annex I-A family under 9903.82.02. Derivative steel, aluminum, copper, other origins and special country/content tiers remain outside this automatic rule unless a later reviewed contract adds them.
See the exact Section 232 beta boundary5 · Fees
Add MPF and HMF only under their own applicability facts
Formal-entry Merchandise Processing Fee and Harbor Maintenance Fee are separate from ordinary and additional tariff duties. HMF is not inferred merely because goods traveled by ocean; the covered-vessel/port applicability fact must be confirmed.
Review boundary
Charges that still require separate analysis
TariffCalc can intentionally withhold an automatic amount for unsupported measures. AD/CVD, quotas, safeguards, unmodeled Chapter 99 provisions, product exclusions, preference eligibility and special origin/content rules are examples that can require a broker or qualified trade professional.