Self-employed alongside a job in Belgium: what it costs

What does it cost to be self-employed alongside a job (zelfstandige in bijberoep / indépendant complémentaire) in Belgium? €111.50 once to register your business, then social contributions — nothing under €1,922.16 of net professional income and 20.50% from that amount, according to the institute for the self-employed’s social security — and personal income tax on your profit. Below are all the amounts of 2026, with a worked example.

Who is self-employed alongside a job, and when do you need the status?

You can be self-employed alongside a job if, next to your self-employed activity, you have a main activity that meets the conditions of the RSVZ / INASTI (the national institute for the self-employed’s social security): a job of at least half-time as an employee, a post as a teacher or civil servant, or a replacement income of at least the minimum pension. The conditions for each main activity, according to the RSVZ:

• Employee: you work at least half-time, measured against the hours of a full-time employee in the same business or sector.
• Teacher: permanently appointed with a post of at least 6/10 of a full timetable, or on contract with at least half a timetable.
• Civil servant building up a pension in another scheme: at least 8 months or 200 days a year, and at least half-time.
• Replacement income (unemployment, incapacity for work, a civil servant’s early pension): at least the minimum pension of a single self-employed person.

If you don’t meet them, you are self-employed as a main job. A permanently appointed teacher with a post of at least 50% to 60% can, however, get the contribution scheme of the side activity on request, as long as the net taxable yearly income as self-employed stays under €9,101.26, according to the rule on being treated as a side activity, article 37. Alongside a job you have the same legal obligations as someone self-employed as a main job.

This article belongs to the first steps as self-employed: every article on them is under Getting started.

Not every extra income needs a status. Services through an approved sharing-economy platform and association work (verenigingswerk / travail associatif) have their own rules, explained in the article on earning on the side without a status. If you are a jobseeker, you can start alongside your benefit under conditions and keep your unemployment benefit for a while, with the RVA / ONEM’s Springplank naar zelfstandige / tremplin-indépendants (the national employment office’s springboard to self-employment). If you doubt whether you really work as self-employed (bogus self-employment), what counts is not how many clients you have but whether there is a relationship of authority. The Commissie Arbeidsrelaties / Commission administrative de règlement de la relation de travail (the federal commission that rules on employment relationships) assesses your working relationship at your request, using four general criteria.

What does it cost to start alongside a job?

In 2026, registering in the KBO / BCE through a business counter costs €111.50. The KBO / BCE is the Crossroads Bank for Enterprises, Belgium’s business register, and a business counter is an ondernemingsloket / guichet d’entreprises. You activate your VAT number yourself in MyMinfin, or the counter does it for you at its own price. And before you start, you join a social insurance fund (sociaal verzekeringsfonds / caisse d’assurances sociales) and, at the same time, a health insurance fund (ziekenfonds / mutualité). The costs fall in this order:

1. Registration in the KBO. An approved business counter registers your business and you get a company number. That costs €111.50, without VAT. The rate is set by the FOD Economie / SPF Economie (the federal economy department) and indexed each year, as the counters state in the rates of Xerius, Partena and Securex.
2. Activating your VAT number with form 604A. You file it after you have your company number and before your activity begins, according to the explanatory note to form 604A. That applies even if you choose the small-business VAT exemption (vrijstellingsregeling / régime de la franchise). You may file the form yourself in MyMinfin, or have an authorised representative such as your bookkeeper or an approved business counter do it. A counter charges its own price for this: Xerius asks €65 excl. VAT, Partena €64.05 excl. VAT or €77.50 incl. VAT. If you only practise a profession exempted by article 44, such as medical care, you need no VAT number (see below).
3. Joining a social insurance fund, before you start, with a fund of your choice, according to the RSVZ. At the same moment you join a health insurance fund, according to the legal obligations of the self-employed. What the fund costs you is the social contributions and the administration fees in the next section.

Join a social insurance fund before you start, so before your first invoice. If you don’t, you risk an administrative fine of €500 to €2,000, and after 30 days you are enrolled with the Nationale Hulpkas / Caisse nationale auxiliaire (the national auxiliary fund).

On other sites you’ll read €60, €70 or €78.65 for activating the VAT number. That is not a legal rate but each counter’s own price, and it differs from counter to counter.

On top of that, your municipality may levy a tax on businesses, a side activity included. Diksmuide, for example, taxes, under its tax regulation 2026–2031, everyone with a company number who is active there on 1 January as a main or side activity, at a flat €145.57. Ask your own municipality whether such a tax exists.

How much in social contributions do you pay alongside a job?

In 2026, according to the RSVZ, you pay nothing on a net professional income under €1,922.16. From €1,922.16 you pay 20.50% of the whole income, at least €98.51 a quarter. From €17,374.08 you pay what someone self-employed as a main job pays, at least €890.42 a quarter, says the RSVZ’s 2026 contributions leaflet. According to the RSVZ page on contributions, your fund’s administration fees come on top.

Your net professional income is your gross professional income minus your business expenses and professional losses, as the tax administration establishes it. There is no exempt first band: as soon as you reach €1,922.16, the whole income counts. The contribution is 20.50% up to €75,024.54 and 14.16% on the part between €75,024.54 and €110,562.42, with a maximum of €5,103.05 a quarter, according to the RSVZ’s 2026 contributions leaflet.

Provisional and final. A year’s contributions only get their final amount when the tax authority reports that year’s income to your fund. So, according to the RSVZ, you first pay provisional contributions based on your income from three years before. If you weren’t self-employed yet then, you pay a provisional contribution set by law: €98.51 a quarter, until the end of the third full calendar year. If you expect to earn less than €1,922.16, you can have that provisional contribution reduced to 0 on request, with objective evidence. As soon as your income is known, the provisional contributions are regularised: you pay the difference or you get money back.

If you had your provisional contribution reduced and your actual income turns out higher, the final settlement charges not only the supplement but also surcharges.

You pay by quarter: the contribution must be in your fund’s account by the last day of the quarter at the latest. According to the RSVZ, every quarter a 3% surcharge is added to the unpaid part, and on 1 January of the following year a further one-off 7%.

On top of the contributions, your fund charges administration fees to cover its costs. They differ by fund: at Partena they are, according to its 2026 rates, 4.20% of the contributions due. That is why some pages show higher amounts than the €98.51 and €890.42 above: according to the FOD Sociale Zekerheid, those amounts include a fund’s administration fees, the legal amounts do not.

If you are retired and work as self-employed, a scheme of its own applies. In 2026, according to the RSVZ, you pay no social contributions on an income under €3,844.32, and from €3,844.32 a reduced contribution of 14.7%, instead of the 20.50% paid by someone self-employed as a main job.

The thresholds and amounts in this section are those of 2026 and change on 1 January 2027. The rules for the side activity itself may change too. Check the amounts with your fund every January.

How much personal income tax do you pay, and when?

The profit from your side activity becomes part of your taxable income, together with your salary, and is taxed in personal income tax on one progressive scale from 25% to 50%. Your extra income therefore falls in your highest band. From income year 2026, as self-employed you no longer get a surcharge for making no tax prepayments, but a prepayment still earns a prepayment bonus.

According to the FOD Financiën’s tax rates, your taxable income is divided into bands, and each band has its own rate:

The basic tax-free allowance is €11,180 for income year 2026. The bands are indexed, so check them again in January 2027.

The rate your extra income pays is that of the band in which your total taxable income ends. If your profit crosses the edge of a band, it is taxed partly at one rate and partly at the next. The additional municipal tax is not in these rates.

According to VLAIO, from income year 2026, as self-employed you are no longer required to make tax prepayments, and you no longer risk a surcharge. Anyone who prepays anyway gets a prepayment bonus. The prepayments have fixed due dates in the year, and for trade profits and professional income an extra period is added: from 21 December to 20 February of the following year. That is what the reform of personal income tax says in DOC 56 1243/009, which the Chamber adopted unchanged in plenary session on 9 July 2026, as DOC 56 1243/011 records.

From income year 2027 there will be an entrepreneur’s deduction: 10% of your trade profits or professional income, up to a maximum of €311. For income year 2026 that deduction does not apply yet.

You declare your profit every year in your personal income tax return, in MyMinfin (Tax-on-web). According to the FOD Financiën’s page on filing deadlines, the deadline for the online return in 2026, for the 2026 assessment year, is 19 July 2026; with specific income it is 31 October 2026, also online. As a starter you request, according to VLAIO, part 2 of the return, even when you had no income or even a loss from your self-employed activity.

Which business expenses can you deduct?

You deduct either a flat rate or your actual business expenses, and you deduct your social contributions in either case. If you choose your actual expenses, every real business expense you can prove lowers your net professional income, and that is the basis of both your personal income tax and your social contributions. So keep every invoice and every receipt, for seven years.

You have the choice between flat-rate professional expenses and your actual expenses. If you state no expenses in your return, you automatically get the flat rate, according to the FOD Financiën. The flat rate depends on your type of income. For 2025 income, the 2026 return, it was, according to the explanatory notes to part 2:

• Trade profits (winst / bénéfices: trade, crafts): 30%, up to a maximum of €5,930.
• Professional income (baten / profits: the liberal professions): 28.7% on the first €7,540, 10% from €7,540 to €14,970, 5% from €14,970 to €24,920 and 3% above that, up to a maximum of €5,210.

You also deduct your social contributions as a separate expense, whether you take the flat rate or your actual expenses. Supplementary premiums for the health insurance fund and a hospitalisation insurance do not count as social contributions, nor as a business expense.

If you choose your actual expenses, you also deduct costs for a PC, your phone and internet that you use for your work. You must then prove that those costs really relate to your professional activity.

You keep the supporting documents: according to efactuur.belgium.be, all invoices and copies of invoices must be kept for seven years, counted from 1 January of the year after their date.

In BravoLisa, on the Free plan, a photographed receipt or a forwarded invoice becomes a recorded purchase. The payments on your bank statement come in as soon as you upload the statement. That way every expense is in one place.

What do you keep? Every cost listed, and a worked example

Of €5,000 of net professional income in 2026, you keep an estimated €3,000 or €2,750, depending on whether your highest rate is 40% or 45%. That €5,000 is your net professional income as the tax administration establishes it, after deducting your business expenses and your social contributions. You pay €1,025 in social contributions on it (20.50%). Your fund’s administration fees come on top: €43.05 at Partena’s rate, 4.20%. The personal income tax on the €5,000 is, at your highest rate, an estimated €2,000 at 40% or €2,250 at 45%.

First, all the costs together:

The examples below are BravoLisa’s arithmetic on the 2026 rates of the RSVZ and the FOD Financiën / SPF Finances (the federal tax administration). The incomes are invented; the calculation is shown each time.

Example A: €5,000 net professional income

• Social contributions: €5,000 × 20.50% = €1,025.00 a year, or €256.25 a quarter. That is above the minimum of €98.51.
• Administration fees at Partena: €1,025.00 × 4.20% = €43.05, which you pay to your fund on top of your contributions.
• Taxable: the €5,000 is your professional income after deducting your social contributions, so the personal income tax falls on the €5,000.
• Personal income tax, an estimate at your highest rate, without the additional municipal tax and assuming the €5,000 stays within your band:
  • if your taxable income is already between €16,720 and €29,510, that is €5,000 × 40% = €2,000.00, and of the €5,000 you keep €5,000 − €2,000.00 = €3,000.00;
  • if it is already above €29,510, that is €5,000 × 45% = €2,250.00, and of the €5,000 you keep €5,000 − €2,250.00 = €2,750.00.

If you are a starter, for the first years you first pay the provisional contribution: 4 × €98.51 = €394.04 a year. At the regularisation your fund later asks for €1,025.00 − €394.04 = €630.96 more, plus the administration fees on it.

Example B: €1,500 net professional income

That is under €1,922.16, so your final social contribution is 0. As a starter you still first pay €98.51 a quarter provisionally, and you get it back at the regularisation, unless your fund already reduced the provisional contribution to 0 at your request. If you end up earning more after all, remember the surcharges on a reduced provisional contribution (see above).

Set money aside for the regularisation. The provisional €98.51 a quarter is a minimum, not your bill. In example A, the €630.96 only comes once the tax authority reports the year’s income to your fund.

Do you have to charge VAT?

You charge no VAT if you choose the small-business VAT exemption, which is open up to €25,000 of yearly turnover. You do activate your VAT number with form 604A, put the exemption’s mention on every invoice, deduct no VAT and file no periodic VAT return. According to the explanatory note to form 604A, professions exempted by article 44 need no VAT number at all.

Your VAT number is your company number with BE in front. The exemption is a choice: you can always apply the normal scheme.

On every invoice under the exemption you state that you carry out your transactions under the „Bijzondere vrijstellingsregeling kleine ondernemingen” (in French « Régime particulier de franchise des petites entreprises »; in English, the special exemption scheme for small businesses).

Some activities are automatically excluded from the exemption if you carry them out regularly: work on immovable property, supplies in the hospitality sector with a registered till system, and supplies of used materials and waste.

If you go above €25,000 of yearly turnover, the normal scheme applies, with periodic VAT returns.

BravoLisa creates PDF invoices for private clients and clients abroad. If you invoice a Belgian VAT-registered business, you need a structured e-invoice through Peppol (see the next section), and BravoLisa does not send those yet.

Do you have to use Peppol?

E-invoicing through Peppol is mandatory if you have a VAT number and invoice a Belgian VAT-registered business. That applies since 1 January 2026, under the exemption too, and a PDF by email is no longer enough. For private clients and clients abroad it is not mandatory, but you must be able to receive your suppliers’ structured e-invoices, says efactuur.belgium.be.

• Structured e-invoicing required: you have a VAT number and your client is a Belgian VAT-registered business, even if you are under the exemption, as the notice on the end of the tolerance period states.
• Not required for your outgoing invoices: to private clients, to clients abroad, and between two parties of whom one is not VAT-registered. Anyone who carries out only transactions exempted by article 44 does not have to send or receive e-invoices.
• Receiving: even if you only work for private clients, you must be able to receive your suppliers’ e-invoices.

According to the list of solutions, the government offers no free solution of its own for invoices between businesses, but meeting the obligation can cost nothing if it is included with other software or your bank account.

According to the FAQ on e-invoicing, anyone without the means to send and receive e-invoices risks a fine of €1,500 for a first offence, €3,000 for a second and €5,000 for each one after that.

BravoLisa creates PDF invoices only where that is allowed: for private clients and clients abroad. It sends and receives nothing through Peppol. For a client who is a Belgian VAT payer, and to receive e-invoices, you therefore need another Peppol solution.

Is there a maximum income, and when do you become self-employed as a main job?

No income limit ends the status: you only become self-employed as a main job when your main activity no longer meets the conditions, for example if your job drops below half-time. Whether you are self-employed alongside a job depends on your main activity, not on what you earn: a higher income only brings your contribution to the level of someone self-employed as a main job, from €17,374.08. You must report that change of main activity to your fund, according to the RSVZ.

If you go above €17,374.08, your status does not change, only your contribution: from then on at least €890.42 a quarter in 2026.

Your social rights and your pension

If you pay no or reduced contributions alongside a job, you build up no extra social rights as self-employed. You do keep the rights from your main job as an employee or civil servant. Paying higher contributions voluntarily opens no rights, says the RSVZ.

The same goes for your pension, according to the RSVZ: contributions for a side activity give no right to a self-employed pension. If you paid them at the rate of someone self-employed as a main job, you may have built up pension rights for that activity.

Stopping your side activity: the steps and what they cost

Report the stop to your social insurance fund within 15 days, have your business removed from the KBO (€111.50 through a counter in 2026), and close your VAT number with form 604C within one month, yourself in e604 or through a counter at its own price.

1. Your fund: when you stop your self-employed activity alongside a job, you report it to your social insurance fund within 15 days.
2. The KBO: a business counter removes your business; Xerius and Partena charge €111.50 for this legal service.
3. Your VAT number: you file the declaration of cessation, form 604C, through e604 within one month of stopping, according to the explanatory note to form 604A. A counter does it for you at its own price: Xerius asks €65 excl. VAT, Partena €64.05 excl. VAT or €77.50 incl. VAT.

Continued insurance after a voluntary stop is, according to the RSVZ, only open to someone who paid contributions as self-employed as a main job in the quarter of the stop and the three quarters before it. Alongside a job, that is usually not the case.

Frequently asked questions

Can you be self-employed alongside a job as a pensioner in Belgium?

As a pensioner you can earn extra as self-employed, but then the RSVZ's own scheme for a pensioner active as self-employed applies. In 2026 you pay no social contributions on income under €3,844.32. From €3,844.32 you pay a reduced contribution of 14.7%, instead of the 20.50% paid by someone self-employed as a main job.

Do you pay social contributions when self-employed alongside a job?

Only from a net professional income of €1,922.16 in 2026. Below that you pay nothing; above it, 20.50% of the whole income, with a minimum of €98.51 a quarter. As a starter you first pay a provisional contribution of €98.51 a quarter, which you can have reduced to 0 on request if you expect to stay under €1,922.16.

How much can you earn when self-employed alongside a job?

No income limit ends the status. You stay self-employed alongside a job while your main activity meets the conditions, for example a job of at least half-time. Your income only decides your social contributions: from €17,374.08 in 2026 you pay what a main job pays, at least €890.42 a quarter. Your status does not change.

Do you charge VAT when self-employed alongside a job?

You activate your VAT number with form 604A before you start, even if you choose the small-business VAT exemption. The exemption is open up to €25,000 of yearly turnover: you charge no VAT, deduct no VAT and file no periodic VAT return. Anyone who carries out only transactions exempted by article 44 needs no VAT number.

Do you need Peppol when self-employed alongside a job?

Yes, if you have a VAT number and invoice a Belgian VAT-registered business. Since 1 January 2026 that invoice is a structured e-invoice through Peppol, under the exemption too; a PDF by email is no longer enough. The obligation does not apply to private clients and clients abroad, but you must be able to receive your suppliers' e-invoices.

Is there a simplified status in Belgium for being self-employed alongside a job?

The status for working as self-employed alongside a job is self-employed alongside a job itself, with the same legal obligations as self-employed as a main job. Two rules keep it light: under €1,922.16 of net professional income you pay no social contributions in 2026, and up to €25,000 of yearly turnover you can choose the small-business VAT exemption.

A side activity lets you build something of your own while your job gives you security. Knowing every euro in advance keeps it a pleasure, not a surprise.
💜💙 Your BravoLisa Team

This article is for general information purposes only and does not constitute professional tax, legal, or accounting advice. Every situation is different — consult a qualified professional (tax adviser, accountant, or lawyer) for advice specific to your circumstances. BravoLisa does not accept liability for decisions made based on this information.

Last updated: October 2026. Amounts and thresholds can change: always check them with the RSVZ / INASTI, the FOD Financiën / SPF Finances or your social insurance fund.

Sources (34)

Verified on 12 October 2026

1. RSVZ — Zelfstandige in bijberoep
2. RSVZ — Wat betekent dat juist: zelfstandige in bijberoep?
3. RSVZ — Voordelige bijdrageregeling: gelijkstelling met bijberoep (artikel 37)
4. RSVZ — Aansluiten bij een socialeverzekeringsfonds
5. RSVZ — Wettelijke verplichtingen van zelfstandigen
6. RSVZ — Hoeveel sociale bijdragen moet ik betalen?
7. RSVZ — Bijdragen 2026 (brochure, januari 2026)
8. RSVZ — Wat als ik mijn bijdragen niet betaal?
9. FOD Sociale Zekerheid — Sociale bijdragen 2026 (zonder de beheerskosten)
10. Partena Professional — Barema 2026 (tarief van het fonds)
11. RSVZ — Gepensioneerde actief als zelfstandige
12. RSVZ — Krijg ik een pensioen voor de uitoefening van een bijberoep als zelfstandige?
13. RSVZ — Ik stop vrijwillig met zelfstandige zijn, wat nu?
14. FOD Financiën — Verklarende nota bij formulier 604A
15. FOD Financiën — Jaarlijkse klantenlisting
16. Xerius — Tarievenlijst ondernemingsloket 2026 (tarief van het loket)
17. Partena Professional — Tarieven Ondernemingsloket 1 maart 2026 (tarief van het loket)
18. Securex — Ondernemingsnummer aanvragen
19. Stad Diksmuide — Belasting op bedrijfsvestigingen 2026–2031
20. FOD Financiën — Belastingtarieven
21. FOD Financiën — Toelichting bij deel 2 van de aangifte in de personenbelasting, aanslagjaar 2026
22. FOD Financiën — Beroepsinkomen
23. FOD Financiën — Indieningstermijnen aangiften
24. VLAIO — Als zelfstandige betaal je belasting op je inkomen
25. De Kamer — Wetsontwerp tot hervorming van de personenbelasting, DOC 56 1243/009
26. De Kamer — Wetsontwerp tot hervorming van de personenbelasting, DOC 56 1243/011
27. efactuur.belgium.be — Voor wie wordt e-facturatie verplicht?
28. efactuur.belgium.be — Einde van de algemene tolerantieperiode voor e-facturering
29. efactuur.belgium.be — Lijst oplossingen: waar beginnen?
30. efactuur.belgium.be — Specifieke vragen over e-facturering
31. efactuur.belgium.be — Hoe bewaar ik facturen die ik ontving?
32. RVA — Springplank naar zelfstandige (infoblad T158)
33. Verenigingswerk.be — Wat is verenigingswerk?
34. Commissie Arbeidsrelaties — Schijnzelfstandige of schijnwerknemer