Article 44 Calculation and Settlement of Corporate Tax
Source: https://mof.gov.ae/corporate-tax-faq/

1. What exchange rate do I use for UAE CT purposes?

For UAE CT purposes, all amounts must be converted to AED based on the applicable exchange rate set by the Central Bank of the UAE at the time the foreign currency transaction is to be translated into the national currency, unless the Federal Tax Authority allows the taxpayer to use an exchange rate that more accurately reflects the taxpayer’s income.