and the Russian Federation formed the Eurasian Economic Union (EAEU). Armenia and the Kyrgyz Republic acceded to the union in the same year and raised their trade-weighted average of the most-favored nation applied tariff rates for alignment with the EAEU's common external tariff rates.• Article XXIV of the General Agreement on Tariffs and Trade of the World Trade Organization broadly discourages external tariff rates from being raised after the formation of a customs union. However, the present method for calculating the general incidence of duties and regulations of commerce does not necessarily deter upward tariff adjustments by each of the constituent economies.• The general incidence should be calculated to discourage such upward tariff adjustments. Ideally, trade-weighted average pre-customs-union tariff rates of individual countries, rather than that of the prospective customs union, should be adopted as a baseline benchmark.