Cumulation in origin rules treats qualifying inputs from one Party as originating when used in production in the other Party. Originating goods or materials from one Party, when incorporated into production in the territory of the other Party and meeting the origin criteria and other applicable requirements, are treated as originating in the territory of the other Party. The rule establishes a cumulation mechanism for determining origin under the customs tariff origin rules, preserving originating status for qualifying inputs used in cross-border production between the two Parties.