Realistically one could possibly do such a thing over personal contacts but hardly do any advertising to do it openly unless most likely fulfilling certain requirements as others have mentioned. But if you are good and have a large local social network then maybe you can make a bit of pocket money but not likely a living.
Another problem might be competition. What one will notice in Germany is that certain businesses are in over-supply; bakeries, pharmacies and especially hair cutting places. I have at least 20 within a 200 meter radius from my apartment in Stuttgart-West. And because of the over-supply there are a lot of discount places like the chain Klier that are known for paying bad wages with lots of work.
But I've known German women who did hair, nails and make-up and made a relaxed side job out of it but they were at no risk to be in violation of visa regulations in addition to the risk of tax problems if they didn’t report the income. I of course would NEVER actually suggest one bend the law but yes, such unreported economic activity exists to a degree in every country. Or one can simply report the income and pay any taxes due if one is legal. If you are unrestricted workwise, (allowed to be self-employed) then I think such a job might be possible. Cutting hair is not exactly brain surgery.
I researched this subject for you in the internet and came up with quite some conflicting opinions. I am not a lawyer or expert in this filed but it seems that one might not need to legally have any training although hygiene would of course be important. Training for such things exists and helps one’s chance of getting a job. Like many trades in Germany, one can become a “Meister” (expert ) with a 3 year training.
This WAS required until a few years ago to actually open your own shop, but this has supposedly changed. It is certainly not needed anymore to work in hair cutting places as an employee but to do freelance work is the real question. In the internet, many people claim that one needs a training but this idea is also promoted to get people to either pay for a school or to work as an intern or low paying helper for a time to get training. Schools or such businesses thus have a vested interest to claim such things as do people who have done such training who rather not compete with people who haven’t.
Certain “handwork” jobs are given special recognition in Germany including Friseur(in) (someone who cuts hair). One will have to have done a certified training to call themselves this. But what if one doesn’t use this word, just says they cut hair? Like someone who says they will cut wood without actually calling themselves a carpenter?
I could not find a definitive answer in the internet, so I called the Governmental Unemployment Office (Arbeitsamt) and they also did not know and referred me to the Handwerkskammer (association of handworkers). The person I got on the phone did not know and referred me to someone who specializes in such things but unfortunately, their number was always busy when I tried to call. If I ever get through I will let you know what I find out. Or if you message me I can give you the number of the Stuttgart office. I think such rules will not vary from city to city.
I know some people here will also be skeptical. But I am a self-employed clown and juggler. I am completely legal and did not need any kind of degree, training or license to do my job. Yet, there are “officially recognized” degrees available for performers. But it is not a requirement and nobody in the business cares. Customers want to know your experience and what you can do, not what clown school you might have gone to. Thus I wonder if one can still cut hair freelance as long as they don’t say they are a Friseur?
Another factor could be that if you do something from your home they can label it a “place of business”, which might have additional tax consequences. Yet if you are a traveling hair cutter, offering house calls, then this might go around such rules and be attractive to people who for whatever reason can’t get out of the house so easily.
Another thing I noticed after writing most of this, and only then looking at your profile, is that you say you are a hairstylist. Even if you did not do a comparable training as offered in Germany, having some years of professional experience might qualify. I am going to direct message you with the number of the Handwerkskammer since you can better give then the details of your situation. You might want a native speaker to assist since some things might be complicated but fortunately you do speak German. I was going to quite an effort assuming that you, like most new American arrivals, didn’t.
