Can I choose whether my income counts as employment or professional income?

No. The classification follows the substance of the relationship, not the label on the contract. A single client, a fixed monthly amount, set working hours and direct instruction point to employment. Multiple clients, project-based engagements and control over how the work is done point to professional income. Registering as self-employed and issuing receipts does not convert employment income into professional income; it creates a misdeclaration risk instead.