Setting up a company in Belgium: the choices that matter
Sole trader or company, what the deed and the financial plan are for, and the decisions that are expensive to change later.

Most of what is written about starting a business in Belgium is a checklist. The checklist is the easy part. The decisions worth spending an hour on with an adviser are the three or four that are expensive to reverse.
Sole trader or company
Trading in your own name is the cheapest way to start: an enterprise number, a bank account, VAT registration where it applies, and a social insurance fund. The cost is that your personal assets and the business's are the same assets.
A company separates the two. In Belgium the usual vehicle for a small business is the private limited company, which no longer requires a fixed minimum capital but does require sufficient starting means, documented in a financial plan filed with the deed. That plan is not a formality: if the company fails within the first years, it is the document a court looks at to decide whether the founders started with enough.
What the deed does
A company is created by notarial deed, and the articles of association drawn up in it decide things people only notice later: who can bind the company, how shares may be transferred, what happens when a founder wants out or dies, and how decisions are taken when two shareholders each hold half. A standard template is fine for a single founder. With two or more, a shareholders' agreement that anticipates disagreement is one of the cheapest pieces of legal work there is, and one of the few that is always worth doing before the disagreement.
Registrations, in order
Deed and registration with the enterprise court, enterprise number, bank account, VAT if applicable, social insurance for the self-employed, and any sector-specific authorisation. An accountant handles most of this routinely; a lawyer is for the articles, the agreement between founders, and any licence or regulated-profession question.
Where to spend, and where not
Spend on the shareholders' agreement, on a contract template you will use hundreds of times, and on checking whether your activity is regulated. Do not spend on a bespoke deed for a one-person company, and do not skip the financial plan.
Ask any practice you call whether they do company work day to day, whether they offer a fixed fee for a formation, and what it includes.
This page is general information about how these matters usually work in Belgium. It is not legal advice about your own case, and only a lawyer who has read your documents can give you that.