What do you need to start a side business?
To start a side activity, you must obtain an enterprise number, possibly activate a VAT number, and register your activity with the CBE via an authorized business registration office.
28/05/2025
Are you planning to start a side business? Do you want to turn a passion into extra income or offer your skills alongside your main job? A few administrative steps are required to get started. Two are essential: obtaining an enterprise number and activating a VAT number. This article explains how to proceed.

In Belgium, every VAT number is based on an enterprise number. The two are linked, but not identical.
Your enterprise number is your official registration in the Crossroads Bank for Enterprises (CBE). You receive it when your activity is registered via a business registration office.
Your VAT number is the same number, preceded by “BE” (e.g. BE0123.456.789). It is only activated if you are subject to VAT or opt for the exemption scheme.
In short:
Every self-employed activity gets an enterprise number. Only those subject to VAT (or under the exemption scheme) use it as a VAT number.
You must apply through an authorized business registration office, which will register your activity with the CBE.
The one-time cost is approximately €90.
You will need:
a valid ID card (e-ID)
a bank account in your business name
a description of your activities
any required permits or certificates, depending on your sector
Once registered, you will receive your enterprise number immediately. You can then activate your VAT number.
Your enterprise number becomes your VAT number once you request activation. This is also done via a business registration office.
Option 1: VAT liable
Do you expect an annual turnover above €25,000?
Then you are subject to VAT. You must:
charge VAT on your sales or services;
submit periodic VAT returns;
recover VAT on your business purchases.
Option 2: Small business exemption scheme
Do you expect an annual turnover below €25,000?
You can opt for the VAT exemption scheme. In this case:
you do not charge VAT;
you do not submit periodic VAT returns.
This greatly simplifies your administration. However, you cannot recover VAT on your purchases.
New from 2025:
The exemption scheme will be more widely applicable across Europe, making it easier for internationally active entrepreneurs to benefit—provided thresholds are respected.
Once your VAT number is activated, you can start invoicing.
With PIA Go!, you can create professional invoices in just a few clicks:
each invoice is automatically linked to your VAT number;
you can choose from clear, professional templates;
you receive guidance from an accountant.
Invoices created in PIA Go! are also Peppol-compatible, ensuring compliance with new e-invoicing requirements, especially for public sector contracts.
Want to learn more? Check out our article: Make a great first impression with your first invoice (and get paid faster).
Applying for an enterprise number, activating your VAT number, and organizing your administration can feel complex at first.
PIA Go! supports you from your initial registration and helps you set up a clear and structured administration from your very first invoices.
You benefit from the guidance of an accountant who thinks along with you.
What do you need to start a side business?
To start a side activity, you must obtain an enterprise number, possibly activate a VAT number, and register your activity with the CBE via an authorized business registration office.
Do you need a VAT number for a side activity?
In most cases, yes. If your services are subject to VAT, a VAT number is required. If your annual turnover remains below €25,000, you can opt for the exemption scheme.
When are you subject to VAT?
You are subject to VAT as soon as you carry out a regular economic activity for remuneration, even if it is only a few hours per week alongside your main job. The exemption scheme may apply if your turnover remains limited.
What is the difference between an enterprise number and a VAT number?
The enterprise number is your official identification as a self-employed professional. When you are subject to VAT, this same number is activated as your VAT number.
How do you register with the CBE for a side activity?
Registration is done via an authorized business registration office, which records your activity in the CBE. You indicate whether the activity is primary or secondary. If you are subject to VAT, activation can be done at the same time.
