Holding a Greek tax number does not let you invoice anyone. What actually stands between an AFM and a working freelance practice or small company — and in what order.
A question we field almost weekly: the number came through, so can I start invoicing Greek clients now? The answer is no, and the reason is worth understanding rather than simply accepting. The AFM registers who you are with the tax authority. It does not register that you are in business.
The step that does is a separate declaration — the commencement of activity — which opens a professional or commercial activity in your name, records the activity codes describing what you actually do, and fixes the date from which obligations begin. Until that exists you are a taxpayer with a number, not a business with the ability to issue a valid invoice. The distinction is invisible from outside and absolutely decisive from inside.
The activity codes deserve more thought than most founders give them. They determine how your turnover is characterised and how your invoices are treated, and while they can be amended, amending them after a year of filings is an expensive way to learn the lesson. Describe the business you are actually going to run, not the one that sounded simplest to register.
For most foreign founders, a Greek accountant is practical operating support rather than an afterthought. They can manage authorised filings, track which declarations fall due and translate between what you want to do commercially and what the system expects to see. Whether professional representation is legally required depends on the entity and the filing, so do not share personal credentials as a shortcut. Fees vary by complexity and region; get more than one quotation and agree at the outset who is responsible for what.
Social insurance is its own track. Self-employed people register with the insurance body separately from anything the tax authority does, contributions follow their own logic, and for individuals the social-insurance number is a different identifier again from the AFM. Founders who plan around tax alone and discover contributions in month four tend to have miscalculated their real cost of operating here.
Invoicing has been transformed by electronic reporting. Invoice data is transmitted to the tax authority, which means the software or provider you invoice through is a compliance decision rather than a matter of taste. Choose something compliant at the start; retrofitting a spreadsheet habit onto a reporting regime is the sort of project that eats a quarter.
The structural question — operating as a sole trader against forming a company — turns on liability, cost, credibility with clients and the amount of administration you are willing to carry. There is no universally right answer, and the cheapest option to establish is not always the cheapest to run. Take advice specific to your turnover and sector.
One final point for our non-EU clients, because it is the one most often assumed away: an AFM confers no immigration status whatsoever. The right to reside in Greece, and the right to work or run a business here, come through the appropriate permit route and nothing else. The number is a prerequisite for the paperwork, never a substitute for the permission. Rules in all of these areas are revised regularly, so verify the current position with a qualified Greek adviser before committing to a structure.