Zakat on what has accumulated with you upon the completion of the lunar year

Question:
The questioner: I have rented-out real estate, apartments in a building, and I rent them out at varying rates. At the beginning of the year, I receive the rent, and at the end of the year, I receive the rest. How do I pay the zakat on this building?

Answer:
The Shaykh: You must set a specific date for your zakat within the year. On that date, you pay the zakat on whatever has accumulated with you, whether its lunar year has completed or not. You then pay the zakat on the same amount on the corresponding date in the following year. This ensures that the lunar year has completed for all of it, and you will have paid zakat on whatever came to you early or late. You rely on a specific day of the year to pay the zakat on what has accumulated with you, and you do the same on that day in the following year.