Payroll in Belgium 2026: ONSS, withholding tax and payslips

In Belgium the employer withholds three things from gross pay: the employee's 13.07% ONSS social security contribution, the précompte professionnel (the monthly withholding of income tax) and a small special social security contribution. On top of salary it pays its own ONSS contributions of about 25% for most private-sector staff, more for blue-collar holiday pay.

Payroll in Belgium at a glance

Social security contributions (ONSS) in 2026

All contributions are collected by the Office national de sécurité sociale (ONSS). The employee's 13.07% breaks down into 7.50% for pensions, 3.55% for health care, 1.15% for sickness and disability benefits and 0.87% for unemployment. Since 2015 the employer's share has been a single global basic percentage, which varies by group of workers.

What to watch:

• The tax shift. The laws of 26 December 2015 and 16 May 2016 lowered the basic employer contribution for workers in categories 1 and 3 of the structural reduction from 24.92% to 19.88% from the first quarter of 2018, and their wage moderation from 5.67% to 4.27%, so the total is about 25%.
• Structural reduction. For the general category 1 from the third quarter of 2026, the flat amount is 0.14 × (€11,687.74 − S) + 0.16 × (€9,738.14 − S), where S is the quarterly reference wage and each part counts only if positive; it is multiplied by a fixed factor and the work fraction. Above €11,687.74 a quarter (about €3,896 a month) it is nil.
• Very high salaries. Since the third quarter of 2025 (programme law of 18 July 2025), no basic employer contribution or wage moderation is due on the part of the quarterly basic pay above a ceiling: €86,700 from 1 January to 30 June 2026 and €88,434 from 1 July 2026. Personal contributions stay due on the whole pay.
• Work bonus (bonus à l'emploi). It reduces the 13.07% on low pay and offsets the whole personal contribution up to about €2,300 gross a month. For white-collar employees from 1 September 2026 it falls to zero at €3,403.62 a month.
• Other employer contributions include the closing-of-companies fund (FFE), whose rate depends on the type of employer.

Income tax: the précompte professionnel

The précompte professionnel is the income tax withheld every month from the salary. It is calculated on the gross taxable pay, which is the gross salary minus the personal social security contributions, and it depends on the employee's family situation and other rules. The official method is the set of key formulas and scales in Annex III to the royal decree implementing the Income Tax Code (AR/CIR 92), published each year by the SPF Finances. The précompte is an advance: the final income tax, including the additional municipal tax set by each commune, is settled after the employee's annual tax return.

We do not reproduce the 2026 scales here; use the SPF Finances key formulas or scales for the exact amount.

Special social security contribution (CSSS). The employer also withholds this contribution after the personal contributions and the précompte. It depends on the quarterly pay declared to the ONSS and on the household. For a single person taxed individually, the quarterly amount is:

Couples taxed jointly have their own scale, capped at €154.92 or €182.82 a quarter depending on whether the partner has professional income. You withhold a monthly amount in the first two months and settle the exact quarterly amount on the last pay of the quarter; the tax administration makes the final calculation.

Blue-collar holiday pay is paid by the holiday fund, which withholds the précompte: in 2026 it is 17.16% of the taxable holiday pay up to €1,740 and 23.22% above.

Minimum wage, working time and mandatory pay

• Minimum income (RMMMG). The guaranteed average monthly minimum income of collective agreement no. 43 of the National Labour Council (CNT) applies to workers aged 18 and over: €2,154.11 gross from 1 January 2026, €2,189.81 from 1 April 2026 (third phase of the 2021 social agreement, collective agreement no. 43/18 of 24 March 2026) and €2,233.61 from 1 July 2026 after indexation. It is an average: an end-of-year bonus or 13th month counts towards it over the calendar year. Joint committees (commissions paritaires) set sector minimums that cannot be lower.
• Indexation. Most sector agreements index wages automatically on the smoothed health index, often by 2% when a pivot index is crossed or at fixed times, most often once a year.
• Working time. At most 8 hours a day and 40 hours a week; since 1 January 2003 every company must have reduced the working week to 38 hours, although this need not mean exactly 38 hours every week. Hours above 9 a day or 40 a week, or a lower limit in a collective agreement, carry an overtime premium of 50% or 100% depending on the case.
• Holidays. Up to four weeks a year: 20 days in a five-day week, 24 in a six-day week. White-collar employees get their normal pay for holiday days plus a double holiday pay from the employer; when they leave, the exit holiday pay is 15.34% of gross pay (7.67% simple and 7.67% double). Blue-collar workers receive 15.38% of their previous year's gross pay at 108% (8% simple and 7.38% double) from their holiday fund, in May or June.
• End-of-year bonus. The prime de fin d'année, often a 13th month, is set by the collective agreements of each joint committee or by the contract, so check your sector's rules.

Payroll calendar and filings

1. 1Before the first hire: identify as an employer with the ONSS through the WIDE application; you need an enterprise number (BCE). You receive an ONSS number and an employer category.
2. 2Each hire and departure: a Dimona IN at the latest when the worker actually starts, and a Dimona OUT at the latest on the first working day after the contract ends.
3. 3Each pay: pay white-collar employees at least monthly and blue-collar workers at least twice a month, and give a pay statement (décompte de paie) at each final settlement of pay.
4. 4Monthly provisions: if your contributions for the quarter before last exceeded €4,000 and you also owed contributions in the same quarter a year earlier, pay 30%, 30% and 25% of that year-earlier quarter's contributions by the 5th of each month (for the third quarter: 5 August, 5 September, 5 October). Employers without that history pay flat provisions of €450 per worker from the third worker.
5. 5Quarterly: file the DmfA and pay the balance by the last day of the month after the quarter: 30 April, 31 July, 31 October and 31 January.
6. 6Blue-collar holiday pay: the ONSS sends the annual debit notice for the 10.27% in March; it is due on 31 March and must be paid by 30 April.
7. 7Précompte professionnel: declared and paid to the SPF Finances on the schedule it sets.

What a payslip must show. Unless your joint committee has its own rules, the royal decree of 27 September 1966 requires: the employer's name and address; the worker's name, first initial and payroll number; the period; the work performed; the basic pay; the amounts due for work, overtime, public holidays, guaranteed pay and bonuses; benefits in kind; total gross pay; social security deductions; amounts not subject to social security; the taxable amount; the précompte professionnel; non-taxable amounts; the net amount; other deductions; and the net amount to pay. You also keep an individual account (compte individuel) for each worker.

Worked example: €4,000 a month

A white-collar employee, full-time, in the private sector, single and taxed individually, no dependants, employer with fewer than 10 workers in category 1 of the structural reduction, pay from September 2026:

The quarterly pay of €12,000 falls in the €11,211.00 to €12,300.00 band of the CSSS scale: €82.05 + 3.38% × 3 × (€4,000 − €3,737.00) = €108.72 a quarter, or €36.24 a month. The wage moderation uses the ONSS rounding of 5.12% for category 1 (4.27% + 4.27% × 19.88%). For a blue-collar worker the same contributions are calculated on 108% of gross pay, €4,320, and the employer adds 15.84% of that amount for holiday pay. Not included: the précompte professionnel, the 1.60% from 10 workers, the FFE and asbestos fund contributions, and the cost of holiday pay and any end-of-year bonus.

Common mistakes

1. 1Calculating blue-collar contributions on 100% of gross pay instead of 108%.
2. 2Forgetting the 1.60% contribution once you have employed 10 workers on average in the reference period, or applying it below that.
3. 3Withholding a flat CSSS instead of following the quarterly scale for the employee's household, and not settling it on the last pay of the quarter.
4. 4Missing the provisions on the 5th or the DmfA and payment deadline at the end of the month after the quarter.
5. 5Letting a worker start before the Dimona IN has been made.
6. 6Paying only the CNT minimum income when the joint committee sets a higher sector minimum, or skipping a sector indexation.
7. 7Using outdated work-bonus thresholds, which changed on 1 July and again on 1 September 2026.

How Clientlly helps

For Belgium, an administrator enters the payroll rates once in the payroll tax settings: income-tax bands, personal allowance, employee and employer contribution rates and the minimum wage. Clientlly then calculates gross to net and the employer contributions and produces payslips. Because the précompte professionnel follows the SPF Finances key formulas, check the withholding against the official scales, and check your joint committee's minimums and bonuses.

Alongside payroll, the human resources module handles leave requests and approvals with a leave calendar and HR documents, and attendance and time tracking records working hours and overtime. To close the books after the payroll run, see our month-end close checklist.