Why BorderMath does not hard-code a “0% DCTS” list
Preference depends on the country, commodity, date, origin rules and any conditions attached to the tariff measure. A static country list can become misleading when schemes or graduations change. BorderMath therefore uses the live origin-filtered tariff measures. If HMRC returns one simple preferential percentage rate, BorderMath can use that rate as an explicit eligibility-dependent estimate; conditional or ambiguous treatments are not silently applied.
What to check
- the exporting country is currently eligible for the relevant DCTS tier;
- the commodity receives a preference under that tier;
- the goods satisfy the rules of origin;
- you hold the required origin evidence;
- no overriding measure applies.