Thanks for catching my mistake - I did indeed mean Freiberuflich.

> Unlike in many other professions he _can_ be "selbstständig" in the CS field without a degree

I'm not an expert here, I can only tell you that the Finanzamt Köln disagrees with this sentence.

IIRC they lumped "web development" in under "engineering", and therefore required qualification. The only way around it that I've heard of, is some front-ender friends of mine invoicing as "Web Designer", which counts as an artistic profession.