Financing of your PhD
There are different ways to can finance your PhD - which one suits for you depends on individual factors.
Position at the University
Research associates on qualification positions typically get a salary according to TV-L 13. The position can be financed either by the federal state or via third party funding. As a PhD student It is possible to be employed a a research assistant as well.
Current job offers can be found here.
A scholarship of one of the several German promotion organisations typically amounts to 1.350.- Euro/monthly. You have to pay for your health insurance yourself. According to § 3 Abs. 44 EStG a scholarship is tax free. A scholarship typically is given for two years with the option of a third year.
If you plan to apply you should keep in mind that the time between an appiication and the possible granting may sum up to several months.
In some structured PhD programmes (e.G. "DFG-Graduiertenkollegs" or graduate schools financed by the "Exzellenzinitiative") you can apply für financal support as well.
You can finance your PhD as well via a non-academic fulltime or parttime job. Some PhD students manage to promote their non-academic carreer while doing their PhD. Some enterprises and instutions offer PhD positions as well. If you get a position like this your non-academic and academic work will be linked closely.