Under Article 58, taxpayers are mandated to maintain essential commercial books and accounting records in Arabic to ensure the precise determination of their tax liability. This obligation applies to all taxpayers, with the specific exception of those who do not possess a permanent establishment within the Kingdom. The Article further empowers the Department to disallow a deduction if the taxpayer fails, without a reasonable excuse, to produce the necessary documentation for an expense or provide sufficient evidence to support the legitimacy of their claim. This provision underscores the importance of proper record-keeping for substantiating tax positions in the Kingdom.