Being self-employed in Germany is necessarily tied to residence. Without some sort of residence permit it will be difficult, if not impossible, for an individual to establish their own business. It is strongly recommended to consult with experts in the field of residence permits and experts schooled in labour, business and tax laws before becoming self-employed.
Residence permits are usually easily granted for highly specialized professionals, e.g. scientists, professional experts or specific senior managers etc., but other qualified professionals can also obtain them. If you want to move to Germany and become self-employed and you meet certain criteria, then you will most likely be issued a residence permit automatically (for both you and your family).
You need to show that your business will have a positive effect on the German economy. A positive effect under German law means that the company brings in investment capital of 500,000 Euros and creates 5 jobs - both are minimum requirements. The business idea will be examined for viability. If the investment capital is less than 500,000 Euros then the case will receive a closer eye.
For those who don't have half a million euros to spare, it is still possible to become self-employed in Germany provided you can meet certain criteria. These criteria would usually be related to the type of business, your qualifications and whether or not you may be doing something that could be done by a German national or some other qualified resident. The local Foreigners Office would most likely ask for certain documentation and then may well check with the local Chamber of Commerce or other organizations to see whether or not your business is specialized enough, economically viable and could not be done by a German or other qualified resident. If your business is deemed acceptable you will most likely be issued a residence permit with limitations as to what you can do and where you can do it. In other words, your permit may restrict you to a certain type of self-employment in a certain geographical area.
Once all the residence permit questions are sorted out, there are a number of steps that have to be taken to establish and register a business. A determination must be made as to the exact classification of your work. Rules and regulations may vary depending on what sort of business you plan to engage in. Like the residence permits, this can be complicated. Again, it is be advisable to get expert, professional help in finding out just exactly where your profession fits in.