Moving house in Türkiye is not finished when the boxes are unpacked. Your "yerleşim yeri" (place of residence) recorded in the national population registry has to be updated too, because that address feeds the electoral roll, school enrolment, official legal notices, healthcare and social assistance records. Under the Population Services Law the change must be reported within 20 working days of moving, and a late report carries an administrative fine.
The good news is that most reports no longer require a trip to a registry office. They can be filed online through e-Devlet (turkiye.gov.tr, Türkiye's e-government portal) using the "Adres Değişikliği Bildirimi" (Address Change Notification) service, run by the Nüfus ve Vatandaşlık İşleri Genel Müdürlüğü — the General Directorate of Population and Citizenship Affairs. The steps below show when the online route works, when you still have to visit the district registry office (ilçe nüfus müdürlüğü), and how to get your barcoded residence certificate once the record is updated.