How is the Zakat calculated for rented properties whose income reaches the minimum threshold (Nisab), knowing that the lease began in the month of Muharram?

He should add the income from rented properties to his gold, silver, and business merchandise. If the total reaches the minimum threshold (nisab) and a full lunar year (hawl) passes, then zakat becomes obligatory. To calculate zakat when wealth increases monthly, one can refer to what has been mentioned regarding zakat on salaries.