A full-time employment contract, and in the evening a project that starts to pay: translations, guitar lessons, a few websites for clients. As soon as that income becomes regular, the question of status comes up. For this complementary self-employment (indépendant à titre complémentaire), Belgium has a separate framework. The obligations stay those of a self-employed person, but contributions follow the real income of the activity and are zero below a certain threshold.
Becoming self-employed on the side takes a few precise steps, from the Crossroads Bank for Enterprises to the social insurance fund. INASTI conditions, 2026 contributions, start-up steps, VAT, taxes and the ONEM rules for people on unemployment benefits are covered below, with the account question at the end.
Key points at a glance:
- The status is for people who already have a main activity, usually salaried work of at least half-time, or who receive a replacement income.
- According to INASTI, people self-employed on the side pay no social contributions on income below €1,922.16 a year (2026 amounts).
- At the start, the provisional contribution is €98.51 per quarter until the end of the third full calendar year.
- Registration with the CBE, through a business one-stop shop, and affiliation with a social insurance fund happen before the activity starts.
- Below €25,000 of annual turnover excluding VAT, the VAT exemption scheme for small businesses is possible, outside excluded sectors.
- Income from the side activity is added to the salary in taxable income.
The status of being self-employed on the side
INASTI, the institute that runs the social status of the self-employed, defines two situations. A person is self-employed on the side when, alongside their self-employed activity, they carry on another professional activity for an employer. So is a person who receives a replacement income linked to an activity as an employee or civil servant that they no longer carry on.
The belgium.be portal points out that people self-employed on the side have the same legal obligations as those self-employed as a main occupation. Affiliation with a fund, quarterly contributions, registration with the CBE: all of it remains mandatory. Only the calculation of contributions adapts to the income of the activity, and that is what makes the status worthwhile.
Employee, civil servant, teacher: the thresholds
The main activity has to carry enough weight for the self-employed activity to stay on the side. For an employee, INASTI asks for at least half-time. The number of hours per month then reaches at least half that of a full-time employee in the same company or sector.
The rules differ in the public sector. A civil servant whose job builds rights in a pension scheme set by law, a provincial rule or the SNCB works at least 8 months or 200 days a year, with at least half the monthly hours of a full-time job. An appointed teacher works at least 6/10 of a full timetable, and half a timetable is enough for a contract teacher. Wikifin, the public financial education website, sums up the rule the same way: 50% of a full-time job in general, 60% for appointed teachers.
Replacement income and assimilation
An unemployment allowance, an incapacity benefit or an early civil-servant pension can also serve as the basis. INASTI sets one condition: this income reaches at least the amount of the minimum pension of a single self-employed person. Otherwise, the self-employed activity becomes the main activity.
A related scheme exists for some people self-employed as a main occupation with limited income, called "assimilation to a complementary activity" or "Article 37". It covers, for example, people who receive a survivor’s pension or a transition allowance, provided their annual net taxable self-employed income stays below €9,101.26. The request goes to the social insurance fund, which applies the assimilation on that basis.
Social contributions when self-employed on the side
Contributions for a side activity follow the professional income of the activity, with bands set every year. The table shows the 2026 amounts published by INASTI.
| Annual professional income (2026) | Contribution when self-employed on the side |
|---|---|
| Below €1,922.16 | No social contribution |
| From €1,922.16 to €17,374.08 | Reduced contribution: 20.50% of the professional income, with no minimum |
| €17,374.08 and above | Same calculation as for a main self-employed occupation |
| Part above €75,024.54 | 14.16% on the part up to €110,562.42 |
For comparison, those self-employed as a main occupation always pay a minimum contribution, calculated on an income of €17,374.08, which is €890.42 per quarter in 2026. On the side, that minimum disappears: below the first threshold, the minimum quarterly contribution is €0. Funds add their management fees on top.
The first years: provisional contributions
At the start, the real income is not yet known, so contributions are provisional at first. At the start of the activity, the 2026 INASTI scale sets the provisional quarterly contribution at €98.51, until the end of the third full calendar year. This amount is 20.50% of the €1,922.16 threshold, spread over four quarters.
After that, provisional contributions are based on the income of three years earlier. Final contributions are calculated on the income of the year itself, once the tax administration has reported it, and the fund settles the difference with a supplement or a refund. If the year’s income looks set to be lower than three years earlier, reduced provisional contributions can be requested on the basis of objective evidence, with the agreement of the social insurance fund.
Income ceiling and social rights
The €17,374.08 threshold sets the ceiling of the favourable scheme. From that amount on, contributions are the same as for a main self-employed occupation, and the status stays complementary as long as the main activity continues.
On rights, INASTI explains that with zero or reduced contributions, no additional social rights are built up in the self-employed scheme. The rights from the main activity, as an employee or civil servant, remain in place. With contributions at the level of a main self-employed occupation, the same own rights are in principle built up.
How to become self-employed on the side in Belgium
The route follows the same order as for a main self-employed occupation, with one point to watch: everything is settled before starting. To become self-employed on the side in Belgium, five steps are usually enough, from checking the conditions to organising payments.
The main activity reaches at least half-time, or a sufficient replacement income is received. The employment contract and the work rules are worth a second read.
Registration is typically done through an approved business one-stop shop, with the NACEBEL codes of the activities. According to business.belgium.be, it then costs €111.50 and gives an enterprise number.
Affiliation with the chosen fund happens before the activity starts. A business one-stop shop can take care of it, for a fee.
For an activity subject to VAT, the enterprise number becomes a VAT number with the FPS Finance before starting. The request is made online at no cost, or through a one-stop shop. The exemption scheme is requested at the same time.
A separate account for the activity is not mandatory. It does make it easier to follow invoices, contributions and tax.
VAT and the exemption scheme for small businesses
An activity subject to VAT stays subject to VAT, even on the side. VAT does offer one simplification: the exemption scheme for small businesses, known in Belgium as the franchise regime. The FPS Finance opens it to businesses whose annual turnover does not exceed €25,000 excluding VAT, whatever their legal form. Some sectors are excluded, such as construction work on buildings, and in the year the activity starts the threshold is reduced pro rata to the start date.
Under this scheme, the business keeps a VAT number but does not file periodic returns and does not charge VAT to its clients. In return, it does not deduct the VAT paid on its purchases. The FPS Finance asks every year, by 31 March, for a client listing giving the total amount of the previous year’s transactions in Belgium, or "0.00" if there were none. Since 1 January 2026, invoices between VAT-registered businesses in Belgium are structured e-invoices sent over the Peppol network, and businesses under the exemption scheme are in principle covered too.
Access to the profession
Basic management knowledge is no longer required in the Brussels-Capital Region or in Wallonia. Brussels dropped it on 15 January 2024, Wallonia on 1 October 2025. Some regulated professions keep their specific professional skills: Wallonia names restaurant owners, bakers and pastry chefs, roofers or heating engineers. Registration with the CBE remains mandatory.
Taxes: incomes that add up
Income from the side activity is professional income. Wikifin states that the income from both activities is added together. Salary and the profits of the self-employed activity are therefore added together in taxable income; the income from the side activity is declared in part 2 of the tax return.
This income is added to the salary and taxed in the highest brackets of the scale, from 25% to 50% according to Wikifin. For contributions, INASTI uses gross professional income minus professional expenses and losses, as set by the tax administration. The same receipts therefore serve for both tax and the fund.
Self-employed on the side and unemployment
A person on unemployment benefits can, under conditions, carry on an accessory self-employed activity while keeping their allowances. ONEM provides two routes, both declared to the payment body.
The general rules cover an activity already carried on for at least three months as an employee before the allowance request. It is declared at the time of the request, with forms C1 and C1A, and is carried on during the week before 7:00 and after 18:00. For the daily allowance, the activity’s daily income counts for the part above €18.44, at the index of 1 September 2026. Some activities are not allowed under these rules unless they are of minor importance, such as hotels and restaurants, door-to-door selling or insurance brokerage. The activity also remains accessory, in hours and in income.
The "Tremplin-indépendants" scheme keeps the right to allowances for 12 months at most while carrying on an accessory self-employed activity. The activity is declared with forms C1 and C1C, and several conditions apply, including not having carried on this activity as a main self-employed occupation in the last 6 years and staying registered as a job seeker, unless exempt. The scheme thus allows an activity to be tested within the framework set by ONEM.
Employment contract and loyalty
For an employee, the employment contract also sets the frame. The FPS Employment points out that a worker refrains from disclosing the employer’s business secrets and from any act of unfair competition, during the contract and after it. A non-compete clause concerns leaving the company. It is only valid under conditions, including gross annual pay above €44,447 on 1 January 2026. Re-reading the contract and the work rules before starting clarifies the frame.
Benefits of the status and moving to a main occupation
The status suits people who want to test an idea without giving up a salary. Its benefits, as they follow from the INASTI rules:
Any change in professional situation must be reported to the social insurance fund, which can help manage the transition. Contributions then follow the rules for a main self-employed occupation, including the minimum contribution, and social rights change with them.
In short: with a job of at least half-time, a self-employed activity can start on the side, with contributions in proportion to income. CBE, fund and VAT are settled before the first client.
A business account for the side activity
For a sole proprietorship, business.belgium.be states that a separate business account is not legally mandatory, while strongly advising one. Next to a salary, a separate account mainly makes the income on which contributions and tax are calculated easy to read. Vivid opens an online business account for sole proprietorships already registered with the CBE:
The Standard plan has no monthly fee, but some services on it are charged. ATM withdrawals are free up to €200 and so is topping up the account by card, after which fees apply. An extra physical card costs €9.90 for standard delivery. The full pricing is on the plans for the self-employed page.
Vivid in brief: Vivid Money S.A., an electronic money institution authorised in Luxembourg, offers sole proprietorships established in Belgium four plans for the self-employed, including Standard with no monthly fee.
Keep the side activity separate from day one
The Standard plan, with no monthly fee, for a sole proprietorship: client invoicing and a Visa debit card included, online application with an ID document.
Frequently asked questions
Who can become self-employed on the side?
A person who already has a main activity, usually salaried work of at least half-time. A replacement income also counts if it reaches at least the minimum pension of a single self-employed person. Civil servants and teachers have their own thresholds.
From what income are contributions due when self-employed on the side?
According to INASTI, no contribution is due below €1,922.16 of annual income in 2026. Between €1,922.16 and €17,374.08, the contribution is reduced. Above that, it follows the calculation for a main self-employed occupation.
How much does registration with the CBE cost?
According to business.belgium.be, registration through an approved business one-stop shop costs €111.50. Activating the VAT number is free online, or costs €60 to €80 through a one-stop shop.
Is VAT charged when self-employed on the side?
An activity subject to VAT stays subject to it. Below €25,000 of annual turnover excluding VAT, the exemption scheme for small businesses is possible, except in excluded sectors. No VAT is then charged and no periodic returns are filed.
Is it possible to be self-employed on the side while unemployed?
Yes, under conditions. ONEM provides the general rules for an accessory activity and the Tremplin-indépendants scheme, which keeps the right to allowances for 12 months at most. The activity is declared with forms C1 and C1A or C1C.
Is side income taxed?
Yes. It is professional income, added to that of the main activity. The income from the side activity is declared in part 2 of the tax return.
Is a business account needed for a side activity?
The law does not require one for a sole proprietorship, but a separate account keeps the income from the activity off the salary account. The rules by legal form are covered in the article on whether a business account is mandatory in Belgium.
This article is for general information only and does not constitute legal, tax or social security advice. The rules and amounts cited are those published by INASTI, ONEM, the FPS Finance, the FPS Employment, business.belgium.be, belgium.be, Wikifin, Brussels Economy and Employment and Wallonia, and may change. Payment services are provided by Vivid Money S.A., an electronic money institution authorised and regulated by the Commission de Surveillance du Secteur Financier (CSSF) in Luxembourg.
