Deferment is not possible. In case you would get admission, you would have to finalize the enrolment process within the respective deadline, irrespective of the fact that you would not be able to arrive in Germany in time. The enrolment process is completely online. Otherwise you will lose your study place and would have to apply again.
Once you are enrolled, you can join classes any time. Late arrival is no problem; respective confirmation letters for visa issues will be provided through the application portal. In the worst case, you will lose one semester and you will commence your studies next semester. However, please note that your examination deadlines will not be interrupted by this; your obligations associated with your studies will remain unaffected.
Furthermore, please also note that the fees have to be paid each semester even if you are not in Germany.
The standard period of study for a master program is 3+2 semesters. All examinations must have been taken for the first time by the end of the 5th semester. Otherwise, they are automatically assessed as "failed" (incl. the Master's thesis). For the Master's thesis there is then one further attempt, for all other examinations you have 2 further attempts, i. e. the program is not limited to five semesters.
If you arrive late and can prove that you applied for a visa in time,
you may request for an extension of the exam deadlines by the amount of time
missed. You can only submit this request once you are here in Germany in
person. You can take missed modules (and exams) later together with
students of the following year. Your duration of study will be extended as a
result.
The application for grace period can be found in the PRIMUSS portal under “Applications and Messages > Select application/form > Others > General Application”.
The application form is empty, i.e. students can explain in detail why they need an extension and the reasons for it. The request and the corresponding supporting documents (confirmation of receipt/application letter from the visa office/embassy and presentation of the visa in the travel application - copy of identity card with arrival stamp in Germany) should be submitted immediately after entry, ideally together with the change of address (change of address from abroad to German address) on the student's portal.