Please note the health insurance
information from the Immigration Office  when obtaining your
(private) health insurance.
In Germany statutory health insurance is mandatory (called the "gesetzliche Versicherungspflicht"). So in order to get enrolled you either have to prove that you have statutory health insurance or that you are exempted from the mandatory statutory health insurance ("Befreiung von der Versicherungspflicht"). More information about this is available here .
Both, the proof of membership in a Germany statutory health insurance or the proof of exemption will be electronically transferred from the statutory health insurance company you get it from to TU Berlin's enrollment office.
For international students this means they either have to register with a German statutory health insurance company or, if sufficiently insured in their home country (e.g. through EHIC , the German-Turkish social agreement  or private health insurance) or privately insured in Germany, can apply for the exemption.
So, only if you already have (private) health insurance which is valid in Germany you can request the exemption from the statutory health insurance requirement ("Befreiung") from a German statutory health insurance company. Keep in mind though, that for the whole time of your studies in Germany you won't be able to get into the statutory health insurance system again.
Please contact any statutory health insurance company with your requests concerning the membership in a statutory healthin insurance, the exemption request or if you have other questions concerning this matter! We suggest to contact:
AOK  on Ernst-Reuter-Platz 2 (talk to Ms. Gohr or Ms. Günther )
Techniker Krankenkasse  in the TU travel agency in the main cafeteria with office hours on Thursdays from 10:30 am - 2:30 pm (talk to Mr. Arcones )
Barmer  on Kurfürstenstraße 84 in 10787 Berlin (talk to Mr. Sachse)