Every taxpayer in Belgium pays personal income tax: it is a tax you pay on your taxable annual income. As a self-employed person, you are therefore taxed on your salary, as well as on the income from your self-employed activity. If you have a one-man business, you declare the latter income via the personal income tax.
Your taxes are calculated based on your net income: the sum of your earnings minus your professional expenses. Since some of you are also an employee as a self-employed person in a secondary occupation, the net income from your salaried job is added to the net income of your business.
Personal income tax taxes your total net income in brackets. A different tax rate applies to each bracket:
In income year 2024 (assessment year 2025), these tax brackets looked like this:
Income bracket | Tax rate |
From 0 to 15,820 euros | 25 percent |
From 15,820 to 27,920 euros | 40 per cent |
From 27,920 to 48,320 euros | 45 per cent |
From 48,320 euros | 50 per cent |
Good to know: part of your net income is never taxed. That is the tax-free sum. That amount depends on a number of factors, but for tax year 2024 it is at least 10,570 euro. So the taxman first deducts that amount from your net income before determining which tax brackets your income falls into.
Example
If your net income from your job and your secondary profession together amounts to 30,000 euro, the tax authorities will first deduct at least 10,570 euro (the tax-free allowance). The remaining 19,430 euro is then taxed in the following brackets:
15,820 euros of the 19,430 is taxed at 25 per cent (tax of 3955 euros)
the remaining €3610 ends up in the second 40 per cent bracket (tax of €1444)
So you pay a combined 5399 euros in taxes on your net income of 30,000 euros, leaving you with 24,601 euros.
Something less fun to read: you will be taxed once more on your taxes. It does not matter whether you are self-employed in a secondary occupation or an employee. This is because the municipality also sits down to levy a tax on the personal income tax you have to pay. How much that tax rate is, each municipality can decide for itself.
The net income from your secondary occupation comes on top of the net income you get from your job. So there is a fairly good chance that the extra penny you earn ends up in 1 of the higher tax brackets: as a result, the net profit from your sideline job is only half in some cases.
Besides personal income tax, you also have the social security contribution:
The rate of social contributions is the same as for the self-employed in main occupation: 20.5%.
However, there are a number of differences:
If you earn less than €1.881,76, you can apply for an exemption for your social security contributions.
The social contributions of the self-employed in a secondary occupation are so-called "solidarity" contributions. You will never or rarely be able to draw social security from these. Your social rights are covered by your main profession, e.g. as an employee, civil servant, pensioner or job seeker.
As a self-employed person in a secondary occupation, you are not entitled to a start-up discount on your social security contributions.
And don't forget VAT, of course:
Paying VAT is also something that usually comes with being self-employed. Unless if you're franchisee, then you don't have to worry about VAT. If you are liable for VAT, you charge VAT on your sales invoices. You pay that VAT back to the government at the end of each quarter. The advantage? You can also deduct the VAT you pay on your purchases (and for which you have a VAT invoice). This only applies if they are professional expenses.
As with social security contributions, you can also apply for a VAT exemption for your secondary profession. You can opt for this if your annual turnover is less than EUR 25,000.
I hope this answer helps you a little further along the way, but if you are looking for accounting advice, you can also turn to an accountant for help or even better, just drop us a message. Don't hesitate to follow our webinar as well.
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