Schengen visa and working visa?

As a South African citizen you need to have a visa before entering Germany. And this visa has to be applied for in the country where you are resident or a citizen.

If you enter Germany with a Schengen tourist visa then you will be expected to leave within 90 days and not exceed the 80 in 180 day rule (depending on exactly what type of visa you have the number of days might vary). You are not planning to do that, but rather to continue your stay on another visa which you have already required.

While this means that you would be in Germany on a legal visa, you might still be flagged for not leaving the Schengen area within the 90 days which might affect your chances of returning, in the future.

The laws are not stipulating for such situations and it is unclear if you are able to do this or not.

I have the feeling that this might not be allowed, and you might be expected to leave the Schengen area before returning to Germany on your new visa. This could mean just going for a weekend trip to a non-Schengen country such as the UK, or returning to your home country.

Airlines are often cautious, and if they see that your planned return is after the Schengen tourist visa expires then they might refuse to even carry you. Even if you do have another visa.

As such then I would suggest that you contact the German embassy in South Africa and ask them explicitly for your case to get a clear answer so that you don't make a costly mistake. And then you can provide this to the airlines if requested.

You can then post this answer on here for others who might be in your situation.