Article 14 stipulates that taxpayers must generally maintain registers and books of accounts in Omani Rials. However, with prior authorisation from the Tax Authority, a taxpayer may maintain records in a foreign currency. If such permission is granted, the final taxable income or loss for the accounting period must still be converted and computed in Omani Rials. This conversion must use the average of the buying and selling rates published by the Central Bank of Oman prevailing on the last day of the relevant accounting period.