How is the Zakat calculated for rented real estate according to the two common systems in Egypt, knowing that it was built for personal use then rented out due to a need for money?

A monthly rental agreement for life, where the owner cannot terminate the lease at the end of each month, is not valid. Instead, the duration must be specified, or both parties must have the right to terminate the agreement at the end of each month. It is permissible to rent a property for a fixed period of 69 years for a specified rent, and neither party has the right to terminate it before the expiry of the term. It is also permissible to pay one-third of the property's price as part of the rent, then pay half of the value until what has been paid is exhausted, and then pay the full rent. Zakat (definition) is not obligatory on these leased properties; rather, it is obligatory on the rent if it reaches the nisab (definition) (threshold) and a hawl (full lunar year) passes over it. So, if the rent is 40,000 for two years, and a year passes over it, zakat becomes obligatory on 20,000 of it, and zakat on the other 20,000 becomes obligatory in the second year.