Understand · Follow the changes
Reform sandbox: what if we changed the rules?
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Since 1 November 2026, withholding tax on pay has been calculated differently (Royal Decree of 27 September 2026). The calculations on this page still follow the previous rules: for pay received from 1 November, withholding tax and net pay may differ. Update in progress.
This simulator uses the official 2026 rules and lets you change every parameter: tax-free amount, tax brackets and rates, lump-sum expenses, work bonus, contributions. Example of a hypothetical simulation: with a tax-free amount of €15,000 instead of €11,550, a single white-collar worker on €3,000 gross would keep €1,097 more over the year.
You can also compare your net pay under the official 2024 and 2025 rules, and share your scenario with a simple link.
How the sandbox works
- The fields are pre-filled with the rules in force on 1 October 2026. Change one: the calculation is redone straight away, with Indexo’s engine.
- The main result is net pay for the year, once tax has been settled by the tax assessment notice (aanslagbiljet / avertissement-extrait de rôle): this is what you really keep.
- The table of typical profiles shows the effect of the same parameters on other situations.
- At present, the tax-free amount has its own scale (25% up to €11,750, then 30%): changing the tax brackets does not change it. Untick ‘Value the tax-free amount on its own scale’ to apply your brackets to it, as the Act of 15 July 2026 provides from 2029 income onwards.
- The ‘Back to the official rules’ button resets all parameters to their legal value. The ‘Copy the link to this calculation’ button saves your whole scenario in the page address, so you can share it.
- Each result is a hypothetical simulation: it shows the mechanical effect of a parameter, without saying anything about its effects on employment, wages or the State budget.
The official rules for 2024, 2025 and 2026
| Parameter | 2024 | 2025 | 2026 |
|---|---|---|---|
| Withholding tax: annual scale limits | 15,830 / 27,940 / 48,350 | 16,310 / 28,790 / 49,820 | 16,710 / 29,500 / 51,050 |
| Withholding tax: tax-free amount | €10,580 | €10,900 | €11,170 |
| Employees’ lump-sum expenses (maximum) | €5,750 | €5,930 | €6,070 |
| Work bonus, part A, white-collar (maximum per month) | €118.22 | €120.59 | €127.54 |
| Work bonus, part B, white-collar (maximum per month) | €159.43 | €162.62 | €171.99 |
| Work bonus: zero above (gross per month) | €3,207.40 | €3,271.48 | €3,403.62 |
| Fiscal bonus, part B | 52.54% | 52.54% | 63% |
| Tax: tax-free amount (income for the year) | €10,570 | €10,910 | €11,550 |
| Tax: scale limits | 15,820 / 27,920 / 48,320 | 16,320 / 28,800 / 49,840 | 16,720 / 29,510 / 51,070 |
| Tax: marital quotient (maximum) | €13,050 | €13,460 | €11,780 |
| Tax: own scale of the tax-free amount (end of the 25% and 30% brackets) | 11,120 / 15,820 | 11,460 / 16,320 | 11,750 / 16,720 |
| Personal social security contribution | 13.07% | 13.07% | 13.07% |
| Special social security contribution (maximum per month, household) | €60.94 | €60.94 | €60.94 |
The tax-free amount in the 2025 withholding tax (€10,900) is derived from two examples published by Securex, which the engine reproduces to the cent. The 2025 withholding tax reductions for two or more children were not found: for those situations, the comparison with 2025 is not shown. Self-employed contributions for 2024 and 2025 are not loaded yet.
The sandbox
Enter your situation, then change the rules. Everything is calculated in your browser; nothing is sent. The results are hypothetical simulations.
The tool could not be displayed. Reload the page (Cmd + Shift + R on a Mac, Ctrl + F5 on a PC).
Four scenarios, five profiles
| Scenario | Single white-collar worker, €2,000 | Single white-collar worker, €3,000 | Single white-collar worker, €5,000 | Couple, one income, €3,500, 2 children | Self-employed, €40,000 a year |
|---|---|---|---|---|---|
| Tax-free amount raised to €15,000 | +€91.40 | +€91.40 | +€91.40 | +€157.67 | +€91.40 |
| Work bonus abolished | −€198.86 | −€52.55 | €0.00 | €0.00 | €0.00 |
| Second bracket at 35% instead of 40% | +€12.61 | +€54.65 | +€57.02 | +€29.29 | +€57.02 |
| Social security contribution of 12% instead of 13.07% | −€9.89 | +€5.92 | +€3.94 | +€8.71 | €0.00 |
These scenarios are calculation examples, not proposals. For the measures actually voted, see Reforms, year by year and What’s changing.
Further reading
- What’s changingThe calendar of all the 2026-2027 changes and your net pay after each one.
- Reforms, year by yearThe approved stages of the tax reform, from 2025 to 2031, applied to your situation.
- The State’s till receiptWhere your contributions and tax go, by main area of public spending.
- Salary indexationYour sector’s mechanism and its effect on your net pay.
- Tax refund or tax to payWhat the first stage of the reform changes for your 2026 income.
- Method and sourcesThe parameters in force, their sources and the dates they were checked.
Frequently asked questions
Are the sandbox results forecasts?
No. They are hypothetical simulations: they show what your net pay would become if one parameter changed, all else being equal. They do not take into account a reform’s effects on wages, employment or public finances.
Why doesn’t the monthly withholding tax change when I change the tax?
Withholding tax is only an advance on income tax. The sandbox directly calculates the final tax for the year, the one on the tax assessment notice. Lump-sum expenses, the social security contribution and the work bonus, on the other hand, also change the monthly pay.
How do I share my scenario?
Below the result, the ‘Copy the link to this calculation’ button saves all the fields in the page address (after the # sign). Anyone who opens the link sees the same scenario. Nothing is stored on a server.
Can I calculate my net pay with the 2024 rules?
Yes, for employees: choose 2024 or 2025 in ‘Also compare with the rules for’. Gross pay is the same in both columns, without indexation: the comparison shows the effect of the rules alone, in euros of the chosen year.
What next?
- Reforms, year by yearThe stages actually voted, applied to your salary.
- The State’s till receiptWhere your contributions and tax go.
- Your net pay curveHow net pay changes as gross pay rises.
Sources
Parameters in force on 1 October 2026. Each parameter links to its source, the official one where it exists; a secondary source is flagged as such.
- Précompte professionnel : calcul sur les rémunérations mensuelles à partir du 01.01.2024, FPS Strategy and Support (BOSA).
- Le bonus à l’emploi renforcé au 1er avril 2024, UCM (secondary source).
- Fiscoliste, amounts for January 2025, Securex (secondary source).
- Récapitulatif des principaux plafonds fiscaux, exercice d’imposition 2026 – revenus 2025 (23 December 2024), Wolters Kluwer (secondary source).
- Récapitulatif des principaux plafonds fiscaux, exercice d’imposition 2027 – revenus 2026 (23 December 2025), Wolters Kluwer (secondary source).
- Taux 2025 pour le calcul du précompte professionnel (7 November 2024), SBEP (secondary source).
- Nouvelles règles en matière de précompte professionnel pour 2026 (29 December 2025), Securex (secondary source).
- Nouvelles règles en matière de précompte professionnel pour 2025 (19 December 2024), Securex (secondary source).
- The work bonus on 1 February 2025, Partena Professional (secondary source).
- Fiscoliste, amounts for January 2026 (version 1), Securex (secondary source).
- Fisc en poche 2025, Xerius (secondary source).
- Fiche de salaire à la loupe 2026 (information as of 3 September 2026), CSC/ACV (secondary source).
- Calcul du précompte professionnel : annexe III de l’AR/CIR 92 et formule-clé 2026, FPS Finance.
- Instructions administratives : le bonus à l’emploi, NSSO.
- Instructions administratives : les cotisations de sécurité sociale, NSSO. Cross-checked with: UCM, Securex and the FEB (via the Walloon Public Service) for the basic employer rate in the private sector: 19.88% basic contribution and 5.12% wage moderation contribution, making 25%.
- La cotisation spéciale pour la sécurité sociale, NSSO.
- Taux d’imposition, revenus 2025 et 2026, FPS Finance.
- Cotisations sociales des indépendants 2026, FPS Social Security.