How TariffCalc produces a US duty estimate.

1. User-supplied facts

The estimate begins with explicit inputs.

The current US calculator requires an HTS code, country of origin, intended import date, customs value, transport mode, quantity and quantity unit where applicable. It does not infer a legally binding classification from a product description.

2. Versioned tariff schedule

The import date selects an eligible HTS release.

A published schedule is chosen only when its effective period covers the selected date. Historical archived versions remain available for date-correct calculations. New releases are staged, compared and tested before publication, and the previous release remains available for rollback.

3. General duty

The rate-bearing line may be an ancestor.

A ten-digit statistical reporting line may inherit its general rate from a parent heading. TariffCalc walks the HTS hierarchy and records the exact rate-bearing code. It currently calculates Free, simple ad valorem, and selected unqualified specific and compound formulas.

Conditional, minimum/maximum, tiered or cross-referenced formulas remain incomplete unless a dedicated deterministic rule exists.

4. Chapter 99 and Section 301

Additional duty is applied only from an explicit supported reference.

The selected HTS line and its ancestors are checked for Chapter 99 references. For China-origin goods, a supported Section 301 percentage is added only when the official schedule explicitly references a deterministic 9903.88 or 9903.91 rule in the versioned registry.

Description-specific exclusions, overlapping rules and unmodeled Chapter 99 references are not treated as exemptions. They produce a review-required warning.

5. Customs fees

MPF and HMF are separate components.

The formal-entry Merchandise Processing Fee uses its versioned percentage, minimum and maximum. Harbor Maintenance Fee is modeled for the selected ocean mode. Special entries, exemptions and port eligibility are not inferred.

6. Coverage and audit record

The result preserves what was included and what was not.

Every result separates inputs, components, formulas, warnings and sources. A user can save a private-by-link immutable snapshot. Its SHA-256 integrity hash covers the inputs, result, warnings and engine version, so the page can verify that the stored record has not changed.

Section 232 is automated only for the locked China-origin, declarable HTS 7208 beta at 50% of full customs value. All other Section 232 cases, Section 122, AD/CVD, quotas, safeguards, excise, preference eligibility and unmodeled Chapter 99 rules remain outside current automatic coverage.