Source policy
A rule is only as good as the source behind it. This page lists the source types we treat as authoritative, the ones we use as supporting context, and the ones we will not cite as primary.
Tier 1 — official primary sources
- The destination country's customs authority (e.g. HMRC, US CBP, Thai Customs, Singapore Customs).
- Government tariff lookup tools (e.g. EU TARIC, UK Trade Tariff, US HTS, AHECC).
- Sectoral regulators where they own the rule (medicines: MHRA / FDA / TGA / EMA; food + agriculture: USDA APHIS, EU DG SANTE, AQIS; aviation: FAA, EASA, CAA, DGCA; postal: UPU and national postal operators).
- Acts of legislation, statutory instruments, gazetted regulations.
Tier 2 — intergovernmental + treaty sources
- World Customs Organization (HS nomenclature, valuation, origin).
- World Health Organization (controlled substances, pharmaceutical classifications).
- ICAO + IATA (aviation safety, dangerous goods).
- IMO (maritime dangerous goods).
- UN bodies (sanctions, CITES wildlife, cultural-property conventions).
- WTO (tariff bindings, dispute outcomes, trade-policy reviews).
Tier 3 — supporting context
- Carrier published policies (DHL, FedEx, UPS, Royal Mail, USPS, etc.) — used for parcel acceptance / packaging rules but never for legality of the underlying goods.
- Reputable trade-press reporting on rule changes.
- Industry-body guidance (chambers of commerce, sector associations).
Sources we will not cite as primary
- Forums, Reddit threads, Quora answers.
- Travel-blog anecdotes.
- Wikipedia — useful as a starting point, not as a citation.
- AI-generated content from another service.
- Affiliate marketing pages by freight forwarders.
Minimum source bar per rule
Every rule on the site carries at least one Tier 1 or Tier 2 source. Rules earning a high confidence tag carry two or more independent sources, with at least one from Tier 1. Live source-health audit: /source-health.
Related: /methodology, /editorial-policy, /corrections-policy.