The first option is a written confirmation of the availability of the required amount (if there is no scholarship or the scholarship is less than 720 euros per month, then 8,640 euros, as of November 2016) in an account at a domestic bank. This can be either an account in the name of the applicant (the future student) or an account of one of the applicant's parents (or both parents). In the latter case, the applicant's relationship to the account holder must be proven by presenting the applicant's birth certificate.
Additionally, a notarized statement from the parent assuming the costs, as well as a salary certificate of the parent, must be submitted. Furthermore, the applicant for a student visa must present two copies of the page with personal data from the parent's foreign or domestic passport.
The second option is to present a declaration of assumption of financial obligations (behördliche Verpflichtungserklärung) in accordance with §§66-68 of the Residence Act. This declaration must be issued no earlier than six months before the submission of documents for a student visa.
It must specify: the purpose of stay in Germany (studying at a university – Studium) and the solvency of the person signing the declaration. This document is issued by the Foreigners' Office in Germany (Ausländerbehörde, Ausländeramt, Amt für Migration und Integration) at the place of residence of the person signing the declaration of assumption of financial obligations.
Finally, the third option is a blocked account at a bank in Germany. The above-mentioned amount must be transferred to this account from abroad. A special feature of such an account is that no more than one-twelfth of the total amount (720 euros) may be withdrawn from it per month.
As "Russkaya Germaniya" notes, in most regions of Germany any of the above methods of guaranteeing funding for a stay in Germany during studies is possible, meaning local foreigners' offices do not object to any of the three. However, in a few regions of Germany (there are not many), local foreigners' offices require only the opening of a blocked account. A future student of a German university should find out in advance whether the place of their future study is among those regions where opening such an account is required. Otherwise, there is a risk of being late with document processing before the start of the academic year.
In conclusion, we note that when submitting documents, one should be prepared for the fact that consular officials may also ask about funding for the second and subsequent years of study.