Rules of origin are legal standards that determine how to treat goods from a tariff standpoint based on their country of origin.

What are rules of origin?

A set of legal standards used to determine how to treat goods being traded from a tariff standpoint on the basis of their country of origin. That is to say—different countries, organizations, and trade agreements stipulate different rules for determining which country you can claim as the country of origin for a specific good.

For example: a trade agreement like NAFTA has specific rules of origin that dictate what criteria or inputs a good not wholly produced in a NAFTA country must meet to be able to claim NAFTA as its country of origin.