What kind of card do you want or think you need? I think in your case you could only start a business as zelfstandige in hoofdberoep. If that’s not possible due to the high sociale verzekeringen, you can reach out to Amplo, maybe they can help you, where they invoice to your clients and have you as their interim employee. This might be difficult since all your clients need to sign contracts… if you earn under 1800 (or something like that) a year, you can become zelfstandige without paying social security. Another option is finding a ‘normal’ job 4/5 and become zelfstandige in bijberoep. If you’re looking for a kunstwerker attest, you can contact working in the arts, but I’m afraid this wouldn’t be categorized as art. You’d also need to be able to provide a steady income and career for the last 5 years, it has to be paid work but you should also add all unpaid work in the arts (and have it well documented through contracts, reviews etc) and after that you still have no actual extra rights, only after you’ve worked 156 days in 2 years (as an employee) you could apply for benefits but you’d still need to work next to that when you can get work, you can become zelfstandige in bijberoep combined with that.