What the law says
Belgian tax is worked out on the calendar year's income and declared in the following year, so the page covers income 2026. Residents are taxed on worldwide income whatever their visa or citizenship. Your employer withholds professional tax from each payslip, and the annual return settles the exact bill.
The calculator works out the full-year result in one step. It only runs for a gross salary of at least about €26,803, which is twelve times the full-time minimum wage, because below that level the employment bonus rules change.
Federal income tax rates
Federal tax is progressive on taxable income, which is your salary after ONSS and a lump-sum deduction for professional expenses. Everyone also gets a tax-free amount of €11,550. The calculator applies it by taking off the tax that would fall on that first slice, worth about €2,888 a year at the 25% rate. Each child adds a supplement to the tax-free amount.
| Taxable income | Rate |
|---|
| €0 to €16,720 | 25% |
|---|
| €16,720 to €29,510 | 40% |
|---|
| €29,510 to €51,070 | 45% |
|---|
| Over €51,070 | 50% |
|---|
Social security (ONSS) and deductions
Employees pay 13.07% of gross salary to the social security office (ONSS), deducted by the employer. It funds your health insurance cover, but you must also join a mutual fund (mutualité) to be reimbursed for care. Low earners get an employment bonus that reduces ONSS and tax, which fades out well below the salaries in the examples.
A lump-sum professional expenses deduction of 30% of your salary after ONSS is applied, up to €6,070 a year. The special social security contribution (CSSS) is an extra monthly deduction that rises with pay and reaches a cap of about €731 a year at higher incomes.
Municipal surcharge
On top of federal tax, your municipality charges a surcharge as a percentage of the federal tax. Most municipalities set it between 6% and 8%, and the calculator uses 7%. It depends on where you live on 1 January, so you can change the rate in the calculator to match your commune.
Married couples and the marital quotient
For married couples where one partner earns most of the income, the marital quotient lets the higher earner transfer up to 30% of professional income, capped at €11,780, to the partner. That amount is then taxed in the partner's hands, from the lowest bracket and using their own tax-free amount. The calculator treats the €70,000 example as a one-earner household and applies the quotient. The child supplements raise the tax-free amount: €2,130 for one child, €5,130 for two, €11,440 for three, €18,510 for four and €7,070 for each child after that.
Expat regime
Belgium has a regime for qualifying employees who are recruited from abroad or seconded to Belgium. Part of your pay is treated as a reimbursement of the extra costs of living abroad, and that part is free of tax. The calculator models this as a tax and ONSS free reimbursement of 35% of gross pay, and only when gross pay is above €70,000. Eligibility depends on your role, salary and where you lived before. The ONSS exemption has its own ceiling, which the calculator does not apply. The regime is applied for with your employer, so check the conditions with the tax administration before relying on it.
How to pay less tax, legally
These are mainstream, legal ways to reduce Belgian tax. Which ones apply depends on your household and how you were hired.
Check whether you qualify for the expat regime
Suits: employees recruited from abroad or seconded to Belgium who meet the conditions on role, salary and prior residence. It can lower both tax and ONSS.
Caveat: it is applied for with your employer, the ONSS exemption has its own ceiling, and not everyone qualifies. Get the conditions confirmed before you rely on it.
Use the marital quotient
Suits: married couples where one partner earns most of the income. Moving up to 30% of income, capped at €11,780, to the lower earner shifts it into the lower brackets.
Caveat: it helps most when your partner has little or no income. If both of you earn a similar amount, it brings little.
Ask about tax-friendly benefits in your package
Suits: employees whose employer offers extras such as meal vouchers, eco vouchers or a group pension insurance. Within the legal limits, these can be worth more than the same amount paid as salary after tax and ONSS.
Caveat: the limits and the tax treatment differ by benefit, and the calculator does not model them.
Private pension saving
Suits: people who want to save for retirement and receive a tax reduction on what they pay in. The reduction rate and ceiling depend on the amount saved.
Caveat: the money is locked in until retirement, and the rules change, so check the current figures with the tax administration.
Frequently asked questions
How much tax do I pay on €55,000 in Belgium?
A single employee pays €11,913 in federal tax, a €834 municipal surcharge, €7,189 in ONSS and a €539 special social security contribution, and keeps about €34,526. Try your own figure in the Global Income Tax Calculator.
How does the Belgian marital quotient work?
In a married couple where one partner has most of the income, the higher earner can transfer up to 30% of their professional income, capped at €11,780, to the partner. That share is taxed as the partner's own income, from the bottom of the brackets and with their own tax-free amount, instead of at the higher earner's top rate. In the €70,000 example, €11,780 moves to the partner. The calculator applies it for married households only.
What is the municipal surcharge and why does it differ between towns?
Each Belgian municipality adds its own surcharge, expressed as a percentage of your federal income tax. It depends on where you live on 1 January and most communes set it between 6% and 8%. The calculator uses 7% and lets you change it. On the €55,000 single example the surcharge is €834.
How does the Belgian expat regime work?
For qualifying employees recruited from abroad or seconded to Belgium, part of the salary is treated as a reimbursement of extra living costs and is not taxed. The calculator models it as 35% of gross pay when gross pay is above €70,000, free of both tax and ONSS. On €100,000 that raises take-home pay from about €53,023 to €73,841. You apply with your employer, and eligibility and any cap should be checked with the tax administration.
What is the special social security contribution (CSSS)?
It is an extra social security charge on top of the 13.07% ONSS. It is zero at low incomes, then rises in steps and stops at a cap of about €731 a year. In the examples it is €539 at €55,000 and €731 at €100,000.
Why is take-home pay on my payslip different from the yearly figure?
The employer withholds professional tax each month with a set formula, and the annual return then settles the real bill, so you can get a refund or owe a balance. The calculator shows a full year at one salary, so it matches the final bill, not each payslip. Extras such as a 13th month or double holiday pay, which many Belgian jobs pay, are taxed too and are not in the model.