The Ministry of Finance, through the Tax Department, issued Interpretive Circular no. 54, on 19 October 2021, which refers to the imposition of 10% additional tax for employees with income other than employment income.
Specifically, the circular makes reference to the provisions of article 24 of the Assessment and Collection of Taxes Law which provides that a person who derives income other than from emoluments (e.g., rental income) must declare this other income during the same year that is generated and pay temporary income tax (twice a year).
For further information here: Tax_alert_Additional_10__tax_on_employees_with_other_income_EN