The bill that ends careers here does not arrive in year one. It arrives in year three, and it is calculated on the year in between.
The three pieces to put in place
Six elements, in an order that matters.
A company number, obtained through an approved counter.
Affiliation to a social insurance fund.
A tax activation, depending on your situation.
A separate business bank account.
An invoicing system, however simple.
And an accountant, or at minimum a first appointment.
Why the order matters
Because each step unlocks another: with no company number, no affiliation is possible; with no affiliation, the situation is not in order; with no activation, certain invoices cannot be issued correctly. Doing it out of order does not only block the paperwork, it delays the first invoice, and therefore the first payment.
What each step unlocks
Six practical consequences.
The company number lets you exist as a supplier.
Affiliation opens social cover.
Tax activation determines what appears on your invoices.
The separate account simplifies all the bookkeeping.
The invoicing system makes payments traceable.
And the accountant prevents errors that cost dearly later.
What depends on your region and your situation
The counters, the local formalities and certain support schemes differ by region. This remains general information: the exact procedure is checked with the competent counter and, in case of doubt, with an accountant. What is constant is that an incomplete file costs weeks, not days.
Main or complementary status
Six differences to know before choosing.
Complementary status assumes another main activity.
The contribution obligations are not the same.
Social cover does not open in the same way.
Moving from one status to the other must be declared.
The choice affects your cash from the first quarter.
And the decision is made with an accountant, not alone.
The provisional contribution mechanism
Six points, stated in general terms.
The initial calculation rests on a provisional basis.
That basis does not reflect your real income.
A definitive calculation comes later.
It bears on an earlier year.
The gap can be large if the activity has grown.
And a voluntary adjustment of instalments is sometimes possible, to be checked with your fund.
What to set aside
Six habits that prevent the nasty surprise.
Set money aside on every payment received, not at year end.
Use a separate account, never the current one.
Estimate the share to set aside with an accountant.
Revise that share when the income changes.
Never touch that reserve for an equipment purchase.
And treat that sum as not being yours.
What to prepare before the first appointment
Seven elements, gathered in advance.
A valid identity document.
A precise description of the activity carried out.
The professional address chosen.
The desired start date.
The professional bank details.
An income estimate for the current year.
And the list of questions you want to ask.
How to estimate what the activity will cost you
Seven items to add up before setting your prices.
The contributions, estimated with an accountant.
The tax applicable to your situation.
The counter and affiliation fees.
The depreciation of equipment.
Software and subscriptions.
Sending and returning products.
And the unbillable time, in hours.
What changes when you invoice abroad
Seven points to check before the first cross-border invoice.
The client's country of establishment.
Their professional identifier, if they have one.
The mention that must appear on the document.
The invoicing currency.
The applicable tax treatment, to be confirmed.
The bank charges, and who bears them.
And the payment delay usual in that country.
The timelines to anticipate
Six markers, so the first invoice is not held up.
The counter appointment, to be booked in advance.
The processing of the file, which is not immediate.
Affiliation, which follows obtaining the number.
Tax activation, depending on your case.
Opening the business account.
And the first contribution notice, which comes afterwards.
What to keep, and the special cases
Six items, filed as you go.
The proofs of registration and affiliation.
The letters received from your fund.
The invoices issued, continuously numbered.
The receipts for expenses.
The business account statements.
And the written exchanges with your clients.
The student case
A specific regime exists for students, with its own conditions, ceilings and consequences for other rights. This remains general information and is checked with the social insurance fund and, if needed, with an accountant. The important point is that exceeding a ceiling can have effects beyond contributions alone.
What your bookkeeping must contain
Seven elements, from day one.
Continuous invoice numbering.
A copy of every accepted quote.
The proofs of payment received.
The receipts for professional expenses.
A monthly tracking table.
The contracts and licences granted.
And a backup on a second drive.
What you can deduct
Six common categories, to validate with an accountant.
Shooting equipment and its upkeep.
Professional software and subscriptions.
A share of connection costs.
Sending and returning products.
Training linked to the activity.
And professional bank charges.
The questions to ask your fund
Seven questions, to be answered in writing.
On what basis are my contributions calculated at the start.
When does the definitive calculation happen.
Which year does it bear on.
Can I voluntarily adjust my instalments.
What happens if my income falls.
What steps apply if I change status.
And which documents must I keep, and for how long.
What not to do in the first year
Six decisions to avoid, even when things go well.
Spending on equipment what has not yet been taxed.
Taking on a monthly commitment before measuring your time.
Basing your lifestyle on the transfers received.
Postponing the first appointment with an accountant.
Waiting until year end to file your documents.
And treating a quiet year as the norm.
The accountant question
Six reasons to get one from the start.
The choice of status commits you for several years.
Thresholds and obligations depend on your situation.
A cross-border invoicing error is hard to repair.
The amount to set aside is calculated, not improvised.
Time spent working it out alone costs more than the fee.
And the first appointment is often enough to frame the essentials.
What is decided only once
Five choices that commit you for years.
The status, main or complementary.
The social insurance fund.
The applicable tax regime.
The professional address.
And the activity start date.
Three ways to operate, three consequences
| Framework | What it allows | What it requires |
|---|---|---|
| Registered self-employment | Invoicing directly | A registration and contributions |
| Complementary activity | Topping up a salary | An employer's consent and a ceiling |
| A company | Separating assets from activity | Formal bookkeeping |
What decides the right framework
The expected volume, whether a salary sits alongside, the share of gear bought, and the need to invoice abroad. None of these is settled alone.
What is confirmed before registering
The contribution regime, the treatment of the tax and the applicable thresholds. All three are checked with an accountant; they determine net income far more than the advertised rate.
The most frequent mistakes
Six reflexes that cost dearly.
Treating the transfer received as your income.
Setting nothing aside in the first year.
Mixing private and business accounts.
Choosing a status without costing out what follows.
Issuing invoices without the expected mentions.
And discovering the adjustment mechanism when it lands.
One last marker: this remains general information and does not replace professional advice. The only habit that truly protects you is setting money aside from the first euro, before you even know exactly how much will be needed.
Sources
- SPF Economie, business registration in Belgium
- SPF Finances, Belgian tax authority
- Belgian social security portal
Checked on 27 August 2026. Thresholds and rates change: where this guide and the official source disagree, the official source is right.
