Belgian withholding tax (bedrijfsvoorheffing) for 2027 is calculated with rules the FPS Finance has yet to publish: the scales in annex III to the RD/ITC 92 and the key formula for income from 1 January 2027 are not online at the end of October 2026. What is already fixed comes from the law of 15 July 2026 reforming personal income tax: a higher base amount for the tax-free allowance, higher supplements for dependent children, a lower marital quotient and a fiscal work bonus that stays at 63% of part B. Below you will find what changes, how to calculate withholding tax in five steps with the 2026 rules as a reference, when to file and pay, and how bonuses, holiday pay, arrears, overtime, students and flexi-jobs are treated.
What withholding tax is and why you withhold it is covered in our article what is bedrijfsvoorheffing. This guide is about the turn of the year: what is different on 1 January 2027 and how to build the calculation step by step.
Withholding tax Belgium 2027: what is fixed and what is not
The table sets 2026 income next to 2027 income. The amounts in the law are base amounts before indexation. In the calculation, the FPS works with indexed amounts: the 2026 key formula, for example, uses a tax-free allowance of € 11,170.
| 2026 income | 2027 income | |
|---|---|---|
| Tax-free allowance, base amount | € 4,945 | € 4,990 |
| Supplement for one dependent child, base amount | € 935 | € 1,005 |
| Supplement for two dependent children, base amount | € 2,250 | € 2,260 |
| Marital quotient, maximum base amount | € 5,860 | € 5,030 |
| Fiscal work bonus, part A | 33.14% | 33.14%, 35% only from 2028 income |
| Fiscal work bonus, part B | 63% since August | 63%, 72% only from 2028 income |
| Maximum fiscal work bonus per year, base amount | € 970 | € 970 |
| Tax-favoured overtime hours per year | 180 | 180 |
| Base scale of the key formula | 26.75% to 53.50% | not yet published |
| Maximum flat-rate professional expenses | € 6,070 | not yet published |
| Scale for bonuses and holiday pay | from zero to 53.50% | not yet published |
The law changes personal income tax. Withholding tax follows through the rules the FPS Finance sets by royal decree, and in 2026 that happened only in part. The royal decree of 24 July 2026 raised the reduction for part B of the work bonus and brought the limit for tax-favoured overtime to 180 hours, but left the tax-free allowance and the marital quotient in the key formula untouched. Whatever the 2026 withholding tax did not include, the employee settles in his tax assessment.
What the reform fixes for withholding tax in 2027
The law of 15 July 2026 is published in the Belgian Official Gazette and sets what takes effect per assessment year. For 2027 income, assessment year 2028, this is what matters most for your payroll:
- Tax-free allowance. The base amount rises from € 4,945 to € 4,990. The law also plans further steps for the following years.
- Dependent children. The supplement to the tax-free allowance rises from € 935 to € 1,005 for one child and from € 2,250 to € 2,260 for two. For assessment years 2027 to 2030 the law indexes these supplements with the 2024 index.
- Marital quotient. If the partner has no professional income, part of the income can be allocated to that partner. The maximum drops from € 5,860 to € 5,030 and keeps falling in later years. For single-income households the benefit therefore shrinks.
- Fiscal work bonus. For low wages, withholding tax is reduced by part of the work bonus. For part B that stays 63% in 2027, for part A 33.14%. Only for 2028 income do those percentages rise to 72% and 35%. The law sets the annual maximum of the fiscal work bonus at € 970. How the work bonus itself works out per wage is in our news on the work bonus in 2026.
- Overtime. The limit of 180 tax-favoured overtime hours applies since 2026 and continues in 2027.
Two things do not change yet in 2027. The new withholding of the special social security contribution only starts on 1 January 2028; until then the current scale stays, explained in our article on the special social security contribution. And the correction of the municipal tax base only applies from assessment year 2029.
Withholding tax 2027 scales: when does the FPS Finance publish them?
Withholding tax rests on two documents the FPS Finance publishes every year:
- The rules, annex III to the RD/ITC 92. They contain the scales for exceptional payments, holiday pay, arrears and the special cases.
- The key formula. You use it to calculate withholding tax on the ordinary monthly salary: base scale, tax-free allowance, professional expenses and reductions.
The 2026 rules came with the royal decree of 11 December 2025 and were on Fisconetplus on 17 December 2025. The decrees for the 2019 to 2022 rules always fell in the first half of December: the earliest on 7 December 2018, the latest on 16 December 2020. The pattern is stable: mid-December, just before the first January payroll run.
The rules apply to income paid or granted from 1 January. An end-of-year bonus that a fund only pays in January 2027 therefore falls under the 2027 rules. What that means for bonuses is in our guide end of year bonus Belgium tax.
Calculating withholding tax 2027 in five steps
The key formula has worked in the same five steps for years. Here they are with the 2026 amounts. In 2027 you replace them with the amounts from the new key formula.
- Gross annual income. Deduct the personal social security contribution from the gross monthly salary, 13.07% minus the work bonus for low wages, and multiply by twelve.
- Net taxable annual income. Deduct the flat-rate professional expenses: 30% of gross annual income, with a maximum of € 6,070 in 2026.
- Annual tax. Apply the base scale, which already includes 7% municipal tax. Deduct the tax on the tax-free allowance: € 2,987.98 on € 11,170 in 2026. Then deduct the reduction for dependent children, in 2026 € 624 a year for one child and € 1,656 for two, and the reductions for other family charges, such as the one for a single parent. If the partner has no professional income, first allocate 30% of the income to that partner, in 2026 up to € 13,790.
- Monthly amount. Divide the annual tax by twelve.
- Other reductions. Deduct the fiscal work bonus, 33.14% of part A and 63% of part B, and where applicable the reduction for overtime and for personal contributions to a group insurance.
The FPS rounds to the cent at every step. The result is the withholding tax you deduct and pay over. Where it sits on the payslip between social security and the special contribution is shown in our guide from gross to net; the gross-net calculator gives a quick estimate.
Worked example: white-collar employee on € 3,200 gross with two dependent children
A divorced white-collar employee works full time, earns a fictitious € 3,200 gross a month and has two dependent children. As a single parent she also gets € 624 a year on top of the reduction for the children. We use the 2026 key formula and the work bonus since September 2026.
| Step | Calculation | Amount |
|---|---|---|
| Personal social security | € 3,200.00 x 13.07% | € 418.24 |
| Work bonus part A | € 127.54 - 0.27 x (€ 3,200.00 - € 2,937.93) | - € 55.76 |
| Social security after work bonus | € 418.24 - € 55.76 | € 362.48 |
| 1. Gross annual income | (€ 3,200.00 - € 362.48) x 12 | € 34,050.24 |
| 2. Flat-rate professional expenses | 30% exceeds the maximum | - € 6,070.00 |
| Net taxable annual income | € 34,050.24 - € 6,070.00 | € 27,980.24 |
| 3. Base tax | € 4,469.93 + 42.80% on the part above € 16,710 | € 9,293.59 |
| Minus tax on the tax-free allowance | € 2,987.98 | - € 2,987.98 |
| Minus reduction for two dependent children | € 1,656 | - € 1,656.00 |
| Minus single-parent reduction | € 624 | - € 624.00 |
| Annual tax | € 9,293.59 - € 2,987.98 - € 1,656.00 - € 624.00 | € 4,025.61 |
| 4. Per month | € 4,025.61 / 12 | € 335.47 |
| 5. Minus fiscal work bonus | 33.14% x € 55.76 | - € 18.48 |
| Withholding tax per month | € 316.99 |
After the special social security contribution of € 21.44, the employee keeps € 2,499.09 net. Without dependent children, withholding tax would be € 190 a month higher.
In January 2027 this calculation changes in two places. If the salary rises with indexation, the work bonus falls and taxable income rises. And the amounts in steps 2 and 3 come from the 2027 key formula. The fiscal work bonus percentages in step 5 stay the same, because they are already fixed for 2027.
Which sectors index in January and by how much is in our overview of the January 2027 indexation. If you plan a raise on top of indexation, first check what the wage norm allows in pay rise 2027.
Filing and paying withholding tax around the turn of the year
You must file withholding tax online through FinProf and pay into the account of the FPS Finance withholding tax team. Filing and payment have the same deadline.
| Income for | Monthly return | Quarterly return |
|---|---|---|
| October 2026 | 13 November 2026 | with the quarter |
| November 2026 | 15 December 2026 | with the quarter |
| December 2026 and the fourth quarter | 15 January 2027 | 15 January 2027 |
| 2027 | calendar not yet published | calendar not yet published |
Monthly is the rule. Quarterly is allowed if the previous year's withholding tax stayed below the threshold; for 2025 it was € 50,240. An employer that works through a social secretariat has that secretariat pay the withholding tax, by the penultimate working day of the month after the month or quarter in which you paid the salary.
After the year comes the tax form 281.10 per employee, with taxable pay and withholding tax deducted. For 2026 income you file them by 28 February 2027.
Special cases in 2027: bonuses, holiday pay, arrears, overtime, students and flexi
Not everything goes through the key formula. For these payments the rules set their own scales or exemptions:
| Payment | What applies in 2026 | In 2027 |
|---|---|---|
| End-of-year bonus and other exceptional payments | fixed percentage based on normal annual pay: no withholding tax up to € 10,675, at most 53.50%; bonus from a fund 23.22% | new scale in mid-December |
| Double holiday pay, white-collar | own column in the same scale, for example 36.34% for annual pay of € 26,340 to € 31,830 | new scale in mid-December |
| Blue-collar holiday pay via the holiday fund | the fund withholds 17.16% up to € 1,740, above that 23.22% | new scale in mid-December |
| Arrears and payment in lieu of notice | own scale based on reference pay: nothing up to € 11,860, at most 48% | new scale in mid-December |
| Overtime with premium | reduction for the employee and exemption from paying over for you, for the first 180 hours | unchanged |
| Voluntary overtime | 240 hours without social security or withholding tax | unchanged |
| Student worker | no withholding tax within 650 hours with solidarity contribution | new quota on 1 January |
| Flexi-job | tax-exempt up to the annual ceiling, € 18,440 in 2026 | 2027 ceiling to follow |
Bonuses and holiday pay. On exceptional payments you do not use the key formula but a flat percentage on the full amount, after personal social security. The details per wage are in end of year bonus Belgium tax, those for white-collar holiday pay in our guide on double holiday pay. What changes in 2027 for holiday pay itself is listed in holiday pay 2027.
Arrears. If you pay salary that relates to an earlier year, for example after a dispute, the percentage depends on the normal gross pay of the year before the year the arrears relate to. The same scale applies to a payment in lieu of notice, on the pay that determined it. How that payment is calculated is explained under notice period.
Overtime. For every overtime hour with a statutory premium, the employee gets a reduction of his withholding tax: 57.75% of the base for a 50 or 100% premium, 66.81% for 20%. You also keep part of the withholding tax you deducted: 41.25% or 32.19% of the same base. The calculation rules and examples are in paying overtime, the new system in our news on voluntary overtime.
Students. With a student employment contract and the solidarity contribution, you withhold no tax as long as the student stays within his quota. Beyond that, the ordinary rules apply. How the quota works is explained on student workers and in the short answer to 650 hours as a student.
Flexi-jobs. Flexi pay is tax-exempt as long as it stays below the annual ceiling; that ceiling does not apply to pensioners. If one employer pays more than the ceiling, it withholds tax on the part above it. The conditions are in flexi-job rules 2026.
Young workers. If a young worker starts with you in October, November or December under an employment contract and meets the conditions of article 36 of the unemployment regulations, you withhold no tax on his pay in those months, up to € 5,000 gross a month. That counts for anyone you still hire this autumn.
What to prepare for January 2027
- Ask for the family situation again. Marital status, the partner's income and dependent children determine a large part of withholding tax. In 2027 the child supplements and the marital quotient change, so a correct record matters more than usual.
- Check who qualifies for the work bonus. After the January indexation, wages cross the limits, and the fiscal work bonus changes with them.
- Plan bonuses and arrears. Paid in December, they fall under the 2026 scale; in January, under the 2027 one.
- Note your deadlines. Withholding tax for December 2026 must be filed and paid by 15 January 2027.
- Wait for the mid-December scales and have the first January payroll run use them.
All other changes for employers on 1 January are brought together in what changes in 2027.
What Business Centrum does for you
Business Centrum calculates your employees' withholding tax at every payroll run, together with Acerta, as part of your payroll. As soon as the FPS Finance publishes the 2027 rules, we apply them to the first January payslips, with the right family situation, work bonus and deadlines. Want to know what 2027 means for your wage costs and your team's net pay? Ask for a call back.