Self-Employed as a Secondary Activity in Belgium: 2026 Rules

Being self-employed as a secondary activity (indépendant complémentaire) is one of the most powerful tools in Belgian law for starting a business without risk. It lets you launch a professional activity alongside a salaried job, a civil servant post or even a pension, while paying reduced social contributions and keeping your full employee social protection. In 2026, several legislative changes make this status even more accessible and attractive.

What Is Self-Employment as a Secondary Activity?

Legal definition

Self-employment as a secondary activity is defined by Article 35 of the Royal Decree of 19 December 1967 implementing Royal Decree No. 38 of 27 July 1967, which organises the social status of self-employed workers.

In practice, it applies to anyone who runs an independent activity alongside a main occupation that already grants them social security rights:

Who can become self-employed as a secondary activity?

What this status is NOT

• It is NOT a "light status" free of obligations: you are a genuine self-employed person with a business number, VAT obligations and accounting duties
• It is NOT authorisation to work undeclared: all income must be reported
• It is NOT a way to escape tax: your secondary income is added to your other income and taxed at your marginal personal income tax rate

The key figures for 2026

Social contributions

This is the main financial advantage of the status. Unlike a self-employed person in a main activity, someone self-employed as a secondary activity pays reduced social contributions because they are already covered by social security through their main occupation.

Social contribution scale (2026):

Concrete example:

• Net income from the secondary activity: EUR 15,000/year
• Social contributions: 15,000 x 20.50% = EUR 3,075/year + management fee (~3.05%) = around EUR 3,169/year
• That is roughly EUR 792/quarter

Comparison with a self-employed person in a main activity:

A self-employed person in a main activity with the same EUR 15,000 income would pay the compulsory minimum contribution of about EUR 840/quarter (EUR 3,360/year), which is higher than the proportional calculation. Someone self-employed as a secondary activity, by contrast, pays purely on their actual income, even if it is very low.

Taxation

Income from the secondary activity is added to your other income (salary) and taxed at the progressive personal income tax rate. This means every extra euro earned through the secondary activity is taxed at your highest marginal rate.

Example:

Sophie is an employee with a taxable salary of EUR 40,000/year. She earns an extra EUR 10,000 net through self-employment as a secondary activity.

Extra tax on the EUR 10,000: 6,440 x 45% + 3,560 x 50% = 2,898 + 1,780 = EUR 4,678 Plus municipal surcharges (~7%): around EUR 5,005 Plus social contributions: EUR 2,050

Actual net income from the secondary activity: 10,000 – 5,005 – 2,050 = around EUR 2,945

That is an effective deduction rate of around 70% at the highest marginal rate, which is why optimising deductible expenses is crucial.

What's new in 2026

1. New VAT exemption threshold at EUR 25,000

Since 1 January 2025, the VAT exemption ceiling for small businesses has risen to EUR 25,000 in annual turnover (European Directive 2020/285, transposed into Belgian law). This change is particularly beneficial for people self-employed as a secondary activity:

What this changes in practice:

• If your annual turnover does not exceed EUR 25,000 excluding VAT, you can opt for the VAT exemption scheme
• You do not charge VAT to your clients
• You do not file periodic VAT returns
• You cannot recover VAT on your business purchases
• You must still file an annual client listing (if applicable)

Mandatory wording on invoices:

"Small business subject to the tax exemption scheme. VAT not applicable – Article 56bis of the VAT Code."

When NOT to opt for the VAT exemption:

• If you have significant business expenses with deductible VAT (equipment, software, etc.)
• If your clients are mostly VAT-registered businesses (they recover the VAT anyway)
• If your turnover exceeds or is close to the EUR 25,000 threshold

2. Simplified digital registration

The whole registration process for self-employment as a secondary activity can now be completed entirely online:

Digital procedure (2026):

1. Online enterprise counter: registration via the web portal of your enterprise counter (guichet d'entreprise — Acerta, Xerius, UCM, Liantis, Partena)
2. CBE business number: issued immediately (same day)
3. Affiliation to a social insurance fund: activated automatically upon registration at the enterprise counter
4. VAT activation: can be requested online via MyMinfin (the FPS Finance portal) or via the enterprise counter
5. Electronic signature: via itsme (the Belgian digital identity) for all documents

Total turnaround: 1 to 3 working days to become operational (versus 1 to 2 weeks previously).

3. Integration with MyEnterprise

The new MyEnterprise portal (myenterprise.be), launched by the FPS Economy, centralises all administrative procedures for self-employed people:

• Consulting your status with the CBE
• Tracking your VAT obligations
• Access to your tax returns and assessment notices
• Managing your business data

Tax benefits and deductions

Deductible business expenses

As someone self-employed as a secondary activity, you can deduct your actual business expenses from your taxable income. This is one of the most effective levers for reducing your tax burden.

The most common expenses:

Flat-rate or actual expenses?

You can choose between two methods:

Method 1: Flat-rate expenses

The Belgian tax authorities grant a flat-rate expense allowance of 30% of gross income, capped at around EUR 5,520 (2026). This method is simple: no supporting documents required.

Method 2: Actual expenses

You deduct the expenses actually incurred, with supporting documents (invoices, receipts, bank statements). This method is more advantageous if your actual expenses exceed the 30% flat rate.

Tip: for people self-employed as a secondary activity with turnover above EUR 15,000/year, actual expenses are almost always more advantageous.

Depreciating equipment

Business equipment worth more than EUR 1,000 excluding VAT must be depreciated (spread over several years):

Example: you buy a MacBook Pro for EUR 2,500 excluding VAT. You deduct EUR 833/year over 3 years.

Steps to get started

Step 1: Check your eligibility

Before anything else, make sure you meet the conditions:

• You have an employment contract of at least half-time (check the number of hours on your contract)
• Your employment contract does not contain an incompatible exclusivity or non-compete clause
• Your employer does not prohibit secondary activities (check the work rules)

Point of attention: you are not legally required to inform your employer of your secondary activity, UNLESS your contract or the work rules require it. However, the duty of loyalty (Article 17 of the Act of 3 July 1978) prohibits you from carrying out an activity that competes with your employer's business.

Step 2: Register with an enterprise counter

You can choose among the approved enterprise counters:

Registration cost: around EUR 93.10 (2026).

Documents required:

• Identity card (eID)
• Proof of the main activity (employment contract or employer's statement)
• Description of the planned secondary activity
• Bank details (IBAN of the business account)

Step 3: Affiliate to a social insurance fund

Affiliation is automatic if you choose the fund linked to your enterprise counter. Otherwise, you can choose a different fund.

The main social insurance funds:

• Acerta Social Insurance Fund
• Xerius
• UCM Social Insurance Fund
• Liantis
• Partena
• Securex
• NISSE (national auxiliary fund)

Step 4: Activate your VAT number (if required)

If you opt for the standard VAT regime (or if your turnover exceeds EUR 25,000), you must activate your VAT number with FPS Finance.

Procedure:

• Via MyMinfin (myminfin.be) with itsme
• Or via your enterprise counter
• Or by visiting the relevant VAT control office

Choosing your filing regime:

• Quarterly returns: if turnover < EUR 2,500,000 (the norm for secondary activities)
• Monthly returns: compulsory above EUR 2,500,000 turnover (rare for a secondary activity)

Step 5: Open a business bank account

Belgian law (Article III.89 of the Code of Economic Law) requires every self-employed person to have a business account separate from their private account.

Popular options for people self-employed as a secondary activity:

• Free business account: some banks (such as Finom or Wise) offer free or low-cost business accounts
• Traditional account: KBC/CBC, BNP Paribas Fortis, Belfius, ING (EUR 10-15/month)
• Neobanks: Qonto, Finom, Wise Business (EUR 0-10/month)

Step 6: Choose an accountant (recommended)

Although not compulsory for a sole trader with simplified accounting, an accountant is strongly recommended:

• They optimise your tax deductions
• They prepare your VAT and personal income tax returns
• They advise you on provisions and advance tax payments
• Average cost: EUR 500 to 1,500/year for someone self-employed as a secondary activity with a simple business

Case studies

Case 1: the developer launching a SaaS side project

Profile: Thomas, a .NET developer employed at EUR 4,200 gross/month in Brussels. He launches a project-management SaaS application while self-employed as a secondary activity.

Year 1:

• Turnover: EUR 8,000 (monthly subscriptions)
• Expenses: EUR 3,500 (cloud hosting, domain name, tools)
• Net income: EUR 4,500
• Social contributions: 4,500 x 20.50% = EUR 923
• Extra tax (marginal rate ~50%): ~EUR 1,789
• Actual net income: around EUR 1,788 for the year

Thomas chooses the VAT exemption because his turnover is under EUR 25,000, and opts for actual expenses because his hosting costs are significant.

Case 2: the freelance graphic designer working evenings and weekends

Profile: Amélie, a graphic designer employed half-time (EUR 2,100 gross/month) at an agency in Liège. She takes on freelance assignments in the evenings and at weekends.

Year 1:

• Turnover: EUR 18,000 (branding and web design assignments)
• Expenses: EUR 5,000 (Adobe software, equipment, training)
• Net income: EUR 13,000
• Social contributions: 13,000 x 20.50% = EUR 2,665
• Extra tax (marginal rate ~45%): ~EUR 4,651
• Actual net income: around EUR 5,684 for the year

Amélie chooses the VAT exemption scheme and actual expenses. She is considering moving to self-employment as a main activity next year if her turnover keeps growing.

Case 3: the cybersecurity consultant

Profile: Marc, a CISO at a bank in Brussels (EUR 6,500 gross/month). He delivers cybersecurity training and one-off consulting as a secondary activity.

Year 1:

• Turnover: EUR 35,000 (training courses and one-off audits)
• Expenses: EUR 8,000 (travel, certifications, equipment)
• Net income: EUR 27,000
• Social contributions: 27,000 x 20.50% = EUR 5,535
• Extra tax (marginal rate 50%): ~EUR 10,733
• Actual net income: around EUR 10,732 for the year

Marc exceeds the VAT exemption threshold (EUR 25,000) and is therefore VAT-registered. He charges 21% VAT to his clients and recovers VAT on his business expenses.

Common mistakes to avoid

1. Not declaring your income

ALL revenue from your secondary activity must be declared. FPS Finance cross-checks data (invoices, VAT, bank accounts). The risk of a tax adjustment is real, with fines that can reach 200% of the evaded tax.

2. Confusing turnover with profit

Your social contributions and taxes are calculated on your NET income (after deducting expenses), not on your gross turnover. Always deduct your business expenses.

3. Not making advance tax payments

Even as a secondary activity, the surcharge for missing advance tax payments applies (around 9% in 2026). If your secondary activity generates more than EUR 5,000 of net profit, make advance payments.

Advance payment dates:

• AP1: 10 April (12% benefit)
• AP2: 10 July (10% benefit)
• AP3: 10 October (8% benefit)
• AP4: 20 December (6% benefit)

4. Losing your secondary-activity status

If you lose your main activity (dismissal, end of contract, reduction of hours below half-time), you automatically switch to self-employment as a main activity. The consequences:

• Minimum social contributions of around EUR 840/quarter (even if your income is low)
• Loss of employee social cover
• Obligation to take out your own insurance

Action: inform your social insurance fund immediately of any change in your situation.

5. Competing with your employer's business

The duty of loyalty (Article 17, §3 of the Act of 3 July 1978) prohibits you from competing with your employer. If you work as a web developer for an employer and take on freelance web-development assignments, you risk dismissal for serious misconduct.

Solution: either your secondary activity is in a different field, or you obtain your employer's written consent.

Moving from a secondary activity to a main activity

If your secondary activity grows well, you may consider moving to a main activity. Here are the indicators that it is time to take the leap:

Steps for the transition:

1. Inform your social insurance fund of the change of status
2. Your social contributions will be recalculated upward
3. You will need to take out your own insurance (hospitalisation, guaranteed income, PCLI)
4. Your pension will now be calculated on the basis of the self-employed status

Useful resources

• NISSE (inasti.be): everything on the social status of people self-employed as a secondary activity
• FPS Finance (finances.belgium.be): VAT, exemption, advance payments
• FPS Economy (economie.fgov.be): Code of Economic Law, obligations of self-employed people
• Xerius (xerius.be/fr/calcul): social contribution simulator
• UCM (ucm.be): practical guides for people self-employed as a secondary activity
• MyMinfin (myminfin.be): online tax returns
• MyEnterprise (myenterprise.be): centralised portal for business procedures
• 1890.be: support for Walloon entrepreneurs
• hub.brussels: support in Brussels
• VLAIO (vlaio.be): support in Flanders

Conclusion

Self-employment as a secondary activity is the ideal springboard for entrepreneurship in Belgium with controlled risk. In 2026, legislative changes (the VAT exemption at EUR 25,000, simplified digital registration, MyEnterprise integration) make this status more accessible than ever. It is the perfect way to test a business idea, build a client base and generate extra income, before possibly taking the leap towards self-employment as a main activity. The key to success: good organisation, rigorous tracking of your finances, and support from an accountant to optimise your tax situation.

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This article was written by the Espero-Soft team for the blog dedicated to entrepreneurs in Belgium. The amounts and thresholds mentioned are based on the legislation applicable in 2026. For personalised advice, consult your accountant or your social insurance fund.