What is the ruling on a landlord demanding an 18% annual rent increase, knowing that the agreed-upon increase is 10%, the customary increase is 10%, and Turkish law stipulates 12.4%?

If the lease term between the tenant and the landlord expires, the landlord is not obliged to renew it, and he has the right to request the rent that satisfies him. The tenant has the right to refuse and vacate the premises. Specifying an annual increase by a certain percentage falls under the category of price fixing, and there is generally no harm in the landlord requesting an increase in rent upon the expiration of the contract and before its renewal.