Countries which are members of a customs union, which in some cases may be considered a single customs territory:2
Countries with external territories variously put them inside or outside the main domestic customs area.
External territories of Australia are outside its main customs zone, but the inhabited ones get preferential tariff treatment.5
The following customs territories are outside the customs territory of the People's Republic of China:
Treatment of special territories of members of the European Economic Area varies.
Tokelau is in a separate customs zone from the North and South Islands of New Zealand, as are the freely associated states of Niue and the Cook Islands.678
Though Northern Ireland is considered an integral part of the United Kingdom and is not part of the European Union, to maintain a peaceful resolution of the Northern Ireland Conflict, it has an open border with the Republic of Ireland, which is part of the European Union customs union. Under the Northern Ireland Protocol, internal shipments from Great Britain to Northern Ireland are regulated as imports to the EU, but shipments from Northern Ireland can enter the rest of UK customs union barrier-free.
Further information: Foreign trade of the United States § Customs territory
The customs territory of the United States includes the fifty states, the District of Columbia, and U.S Commonwealth of Puerto Rico.9 The following dependent United States territories are outside the customs territory and most administer customs separately:10
Taiwan is officially titled as Separate Customs Territory of Taiwan, Penghu, Kinmen, and Matsu or Chinese Taipei in the WTO.11
For example: Interim Agreement on trade and trade-related matters between the European Community, of the one part, and the Republic of Montenegro, of the other part. http://ec.europa.eu/enlargement/pdf/montenegro/key_documents/interim_agreementlexuriserv_en.pdf ↩
see the list of customs unions for references /wiki/Customs_union#Current ↩
"New Separatist Recruits for Russia's Customs Union". Eurasianet. https://eurasianet.org/new-separatist-recruits-for-russias-customs-union ↩
Some of the special EU member state territories are covered by EU law (Art.52 TEU and Art.355 TFEU), but nevertheless remain outside the EU customs territory. "Annex 1: Overview of European Union countries" (PDF). Retrieved 21 Apr 2014. /wiki/Special_member_state_territories_and_the_European_Union ↩
"External Territories". Australian Border Force. https://www.abf.gov.au/importing-exporting-and-manufacturing/fta/other-preferential-arrangements/external-territories ↩
Tokelau Customs Regulations 1991 https://www.legislation.govt.nz/regulation/public/1991/0004/1.0/whole.html ↩
Niue Customs Act 1966, Niue Customs Tariff Act 1982 https://niue.tradeportal.org/media/Customs%20Act%201966.pdf ↩
Cook Islands Customs Legislation and Tariffs https://www.mfem.gov.ck/customs-legislation-tariffs ↩
19 CFR 101.1 /wiki/Title_19_of_the_Code_of_Federal_Regulations ↩
19 CFR 7.2 /wiki/Title_19_of_the_Code_of_Federal_Regulations ↩
Separate Customs Territory of Taiwan, Penghu, Kinmen and Matsu (Chinese Taipei), World Trade Organization, retrieved 2014-09-10, Chinese Taipei has been a member of WTO since 1 January 2002. http://www.wto.org/english/thewto_e/countries_e/chinese_taipei_e.htm ↩