In residential and commercial lease agreements, the parties may execute supplementary protocols or new agreements during the term of the lease to increase or redefine the rental amount. However, this raises an important legal question: If the parties agree to redetermine the rent, when can a rent determination lawsuit be filed under Article 344/3 of the Turkish Code of Obligations? In practice, the answer to this question depends on the legal nature of the arrangement made between the parties. Specifically, it must be determined whether the arrangement is merely a supplementary agreement modifying the rent amount under the existing lease relationship, or whether it constitutes a new and independent lease agreement that replaces and terminates the previous contract...