The official exchange rates of foreign currencies against the Uzbek som are determined by the Central Bank of the Republic of Uzbekistan on a daily basis during banking days. These rates are established through market-driven mechanisms, representing the weighted average value derived from trading sessions held at the Uzbekistan Republican Currency Exchange. While the published rates are mandatory for accounting purposes, statistical reporting, and the calculation of customs duties and other state payments, they serve as a reference rather than a binding requirement for commercial banks when setting their own buying and selling rates for retail and corporate transactions.