Obtaining a tax ID number will help you with your various official proceedings such as opening a bank account with certain banks and getting health insurance. Since various administrative procedures require you to submit an official number, a tax ID number can be used to perform such procedural steps before you have received your residence permit.
You can get a tax ID number through https://ivd.gib.gov.tr. Please select “Doğrulamalar” on the menu and click “Yabancılar için potansiyel vergi kimlik numarası/ Potential Tax Number Confirmation for Foreigners” and fill out the form.
You can complete this step online or you can go to the nearest tax office in person.