1. Shipment facts supplied by the user
The estimate starts with destination, country of origin, commodity code, goods value, freight, insurance and other applicable cost inputs. ImportSmart does not infer product composition, a preferential origin or an exemption from a country name alone.
Exchange rates are explicit inputs where the destination currency differs from the entered value. They are not represented as guaranteed bank or customs-authority rates.
2. Classification and origin checks
The commodity code is normalized and checked against the supported destination source. National schedules can require more digits than the internationally shared six-digit HS heading. When a broad code maps to multiple rates, ImportSmart asks for the more specific code.
Origin is treated separately from export country. Preferences, exclusions and special treatments remain explicit because they often depend on rules of origin, product facts or documents that a calculator cannot prove.
3. Customs value, duty and taxes
The selected or automatic destination valuation method determines which entered components feed customs value. A supported simple tariff rate is applied to that value. Destination-specific VAT or GST is then calculated on its supported base rather than as one generic global formula.
Government fees are shown separately where the supported destination path includes them: examples include U.S. MPF and HMF, Australian import charges and New Zealand goods levies.
4. Safe-stop rules for uncertain rates
The automatic result stops instead of guessing when any of the following prevents a defensible simple calculation:
- a specific or quantity-based rate needs units such as kilograms, litres or items;
- a compound rate combines a percentage with another formula;
- multiple current tariff rows or measures remain possible;
- a quota, safeguard, trade remedy or condition needs facts outside the supplied inputs;
- a preference, exclusion, concession or relief has not been verified;
- the destination source is unavailable or the exact item cannot be found.
A stopped automatic calculation is not a zero-duty result. It is a request to verify the missing classification, quantity, measure or treatment.
5. Official source traceability
Supported results identify the source used for the tariff decision. The five destination paths use official material from the USITC, Canada Border Services Agency, HMRC, Australian Border Force or the Federal Register of Legislation, and New Zealand Customs Service.
Some sources are requested when the calculation runs, while others are integrated as a verified data layer. The result can expose effective dates, source versions or timestamps when the underlying path provides them.
6. Scope and professional review
ImportSmart provides planning estimates. It does not issue binding tariff information, origin determinations or customs rulings. Product classification, customs valuation, admissibility, trade remedies, tax recovery and documentary requirements may need review by the relevant authority or a qualified customs professional.
The calculator should not be used to conceal uncertainty. Advanced controls are intended for verified exceptions and manual rates, not for selecting a lower result without supporting facts.