Paying overtime: rules, supplements and compensation

It's Thursday evening. Your best mechanic has already worked late three times this week to wrap up an urgent project. Now he's standing at your desk with a simple question: how does the pay for all those extra hours actually work? And you? You're not entirely sure you're calculating the overtime premium correctly. Or whether he's entitled to compensatory rest. Or whether those voluntary overtime hours count at all.

You're not alone. Belgium's rules on overtime pay are a tangle of legal limits, premiums, sector-specific exceptions and recent changes. In this article, we lay it all out: from the basic 50% premium to the new regime of 360 voluntary overtime hours that takes effect in 2026.

What exactly counts as overtime?

Overtime is any hour a worker performs above the statutory working time. In Belgium, that limit is 38 hours per week (or 40 hours with compensatory rest days), and in principle every hour beyond it is an overtime hour.

But not every extra hour is automatically overtime in the legal sense. There are three categories you need to tell apart as an employer:

Overtime due to an exceptional increase in work. Think of a seasonal peak or a large order that has to go out. For this you need authorisation from the trade union delegation or from the Supervision of Social Laws Inspectorate.

Overtime due to unforeseen necessity. A machine breakdown, an urgent IT problem, a water leak. No prior approval is required here, but you do have to notify the Inspectorate afterwards.

Voluntary overtime. Since the Workable and Agile Work Act, workers can put in extra hours at their own request. More on this later, because the rules have changed considerably of late.

The distinction matters. The category determines not only whether you owe a premium, but also whether the worker is entitled to compensatory rest and which formalities you have to complete.

The overtime premium: 50% or 100%

The statutory minimum overtime premium is 50% on weekdays and Saturdays, and 100% on Sundays and public holidays. This is the part that keeps most employers up at night: how much does an overtime hour actually cost?

The Belgian Labour Act (the Law of 16 March 1971) is clear on the minimum:

On weekdays and Saturdays: a 50% premium. A worker with a gross hourly wage of 20 euros therefore earns 30 euros per overtime hour (20 euros base hourly wage + 10 euros premium).

On Sundays and public holidays: a 100% premium. That same worker then earns 40 euros per overtime hour (20 euros base hourly wage + 20 euros premium).

That is the legal minimum. Many sectors provide for higher premiums through collective labour agreements (CLAs). Some Joint Committees, for example, apply a 100% premium for all overtime after 8 p.m., or extra compensation for night work. So always check the sector-specific provisions of your paritair comité.

Worked example

Take Karim, who normally works 38 hours a week at a gross hourly wage of 18 euros. This week he put in 6 overtime hours: 4 on Thursday (a weekday) and 2 on Sunday.

• 4 overtime hours on Thursday: 4 x (18 + 9) = 4 x 27 = 108 euros gross
• 2 overtime hours on Sunday: 2 x (18 + 18) = 2 x 36 = 72 euros gross
• Total overtime pay: 180 euros gross

That amount comes on top of his normal weekly wage. And that's before we even get to the total wage cost once you factor in NSSO contributions and other employer charges.

Tax advantage on overtime pay

Good news: for the first 180 overtime hours per calendar year, both the employer and the worker enjoy a tax advantage. The employer receives a partial exemption from remitting professional withholding tax. The worker pays less tax on the overtime pay.

That makes overtime a little more affordable. But it doesn't replace the overtime pay itself: the 50% or 100% premium remains fully due.

Compensatory rest: the required offset

Every worker who performs overtime is entitled to compensatory rest. Paying out overtime is only half the story. The other half? Compensatory rest.

The law states that the average weekly working time of 38 hours must be respected over a reference period. By default that period is a calendar quarter, but a sector-level or company-level CLA can extend it to a maximum of one year.

In concrete terms: if a worker put in 44 hours this week, he must work 6 hours less in the coming weeks. That compensatory rest is paid, and the worker simply receives his normal wage.

Can an employee waive compensatory rest?

Yes, in part. A worker can choose not to take the compensatory rest for up to 91 overtime hours per calendar year. Those hours are then paid out (premium included). In certain cases that quota can rise to 130 hours.

Important: this is the worker's choice. As an employer, you cannot impose it. And it applies only to overtime due to an exceptional increase in work or unforeseen necessity. Not to every type of overtime.

What if the rest is not taken?

If the reference period ends and the worker has been unable to take the compensatory rest, those hours are paid out regardless. That is no longer a choice but a legal obligation. So as an employer, you cannot let overtime pile up indefinitely without compensation.

Keeping accurate track of this takes quite a bit of admin. Who performed how much overtime, and when? How much compensatory rest has been taken? What still needs to be offset? It's exactly the kind of admin where mistakes get expensive fast. A payroll partner like Recruit can keep track of this for you, so you know you're always compliant.

Voluntary overtime: the new 360-hour scheme

The biggest change in 2026 regarding overtime pay in Belgium concerns voluntary overtime. This system has evolved considerably in recent years and is now getting a structural basis.

How did it work until now?

Since 2017, workers could perform up to 120 extra hours per year on a voluntary basis, on top of the basic credit of 100 voluntary overtime hours. Those 120 extra hours were the so-called "relance hours" (recovery overtime), originally a crisis measure that was extended time and again.

What made these relance hours special? They were net hours. No NSSO contributions, no professional withholding tax. Net equals gross, so to speak. That made them financially attractive for employer and worker alike.

What changes from April 2026?

The Federal Government Agreement 2025-2029 provides for a structural reform that takes effect on 1 April 2026:

The basic credit for voluntary overtime rises to 360 hours per year. That is a sharp increase compared with the former 100 + 120 hours. Specific rules apply to the hospitality sector and construction (JC 124 and JC 200).

The written agreement is extended. Where the agreement between employer and worker was previously valid for six months, it now runs for one year. Moreover, the agreement can be tacitly renewed.

Transitional arrangement for Q1 2026. Relance hours performed in the first quarter of 2026 are deducted from the total contingent of 240 net hours for the whole of 2026.

Voluntary overtime and compensatory rest

A crucial difference from ordinary overtime: voluntary overtime gives no right to compensatory rest. The worker does receive the overtime pay (a 50% or 100% premium), but does not have to offset those hours with time off.

That makes the system more flexible. But it also means that, as an employer, you have to keep careful track of which overtime is voluntary and which is not. A wrong classification can lead to disputes during a social inspection.

Conditions for voluntary overtime

Not everyone can simply perform voluntary overtime. Strict conditions apply:

• There must be a written agreement between employer and worker
• The worker must take the initiative themselves (you cannot require it)
• The daily limit of 11 hours and the weekly limit of 50 hours still apply
• The agreement must explicitly state that it concerns voluntary overtime

Paying overtime: how the calculation works

Overtime pay is calculated on the worker's normal hourly wage. The calculation looks simple, base wage plus premium, but in practice there are pitfalls.

What counts as base pay?

Overtime pay is based on the worker's ordinary hourly wage. That includes the gross base wage, but not necessarily all premiums and allowances. Shift premiums, seniority allowances and sector premiums count in some cases but not in others. This depends on the CLA that applies in your sector.

NSSO on overtime

The same NSSO contributions are due on overtime pay as on ordinary wages, unless it involves the net relance hours. The employer contribution of roughly 25% (depending on the sector) therefore comes on top of the premium. That makes the real cost of an overtime hour considerably higher than what the worker receives net.

Want to know what an overtime hour really costs you? A gross-to-net calculation gives you a more realistic picture.

Overtime on the payslip

Overtime and the associated overtime pay must be listed separately on the payslip. The worker must be able to see how many overtime hours were performed, at what rate, and how much premium they received. Transparency here is not optional but a legal requirement.

At Recruit, overtime is automatically calculated correctly on the basis of the employment contract and the applicable Joint Committee. That way you avoid manual mistakes and your payroll admin is always in order.

Overtime limits: daily and weekly caps

You cannot have overtime performed without limit. The law sets clear boundaries:

• Daily limit: a maximum of 11 hours per day (or 10 hours under some working arrangements)
• Weekly limit: a maximum of 50 hours per week
• Annual limit: the internal limit may at no point exceed 143 hours above the average working time (or higher under a sector CLA)

That internal limit is a mechanism to prevent overtime from piling up indefinitely without compensatory rest. Once the limit is reached, hours must first be taken back before new overtime can be added.

There's a nuance here. Voluntary overtime does not count towards the internal limit. That was a deliberate policy choice to keep the system workable.

Common mistakes when paying overtime

After years of guiding companies through their payroll admin, we see a number of mistakes come back again and again:

Failing to distinguish between types of overtime. Ordinary overtime, overtime due to force majeure and voluntary overtime each have their own rules. Lumping everything together is guaranteed to cause problems.

Forgetting compensatory rest. The overtime pay is duly paid, but the compensatory rest is never scheduled. The result: a worker who, months later, files a claim for dozens of hours of compensation.

Ignoring sector premiums. The legal minimums of 50% and 100% are exactly that: minimums. Many sectors provide for higher premiums. If you pay only the legal minimum while your CLA prescribes more, you are in breach.

Applying the 91-hour limit incorrectly. Not every worker can simply waive compensatory rest. The quota applies per calendar year and only to specific categories of overtime.

Performing voluntary overtime without a written agreement. Without that agreement, these are legally ordinary overtime hours, with all the consequences that entails, including the right to compensatory rest.

Overtime for part-time employees

A separate chapter that is often overlooked. Different thresholds apply to part-time employees.

Additional hours (above the contractual schedule but below the full-time limit) do not automatically give a right to overtime pay. Only when the full-time limit of 38 hours is exceeded does the right to the statutory premium arise.

But watch out: additional hours below the full-time limit can also give a right to a premium if the worker exceeds a certain credit. The calculation is complex and depends on the type of contract (fixed or variable schedule) and the sector-specific provisions.

Frequently asked questions on overtime pay in Belgium

As an employer, do I always have to pay a premium for overtime? Yes, for all hours above the statutory working time a premium of at least 50% (weekdays) or 100% (Sundays and public holidays) is mandatory. There are no exceptions to this rule, unless your sector prescribes higher premiums.

Can a worker refuse to perform overtime? In principle, yes. Overtime requires the worker's consent, except in cases of force majeure or urgent necessity. Voluntary overtime is by definition not mandatory.

How many voluntary overtime hours may a worker perform in 2026? From April 2026, a structural credit of 360 hours per calendar year applies. Transitional provisions apply for the first quarter. Consult your social secretariat or payroll partner for the exact application.

What is the difference between compensatory rest and offset rest? In practice, both terms are used interchangeably. Compensatory rest refers specifically to offsetting overtime in order to respect the average weekly working time. Offset rest can be broader and also relate to public holidays.

Is overtime on Saturday more expensive than on weekdays? No, legally speaking the same 50% premium applies to both weekdays and Saturday. The higher 100% premium applies only to Sundays and public holidays. Some sectors do make a distinction through a CLA.

What happens if I don't comply with the overtime rules? The Social Inspectorate can impose fines. These range from administrative penalties to criminal sanctions in the event of repeated or serious breaches. In addition, the worker can claim outstanding overtime pay, increased with statutory interest.

In short

The rules on overtime pay in Belgium are layered. You have the statutory premiums (50% on weekdays, 100% on Sundays and public holidays), the mandatory compensatory rest, the distinction between ordinary and voluntary overtime, and, since 2026, an expanded regime of 360 voluntary hours with tax advantages.

As an employer, it's essential to register the right type of overtime, apply the correct premium and keep track of the compensatory rest. Mistakes get expensive, not only financially, but also in terms of trust with your workers.

The legislation is complex, but with the right structure and a reliable payroll partner it doesn't have to be a nightmare.

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How Recruit helps you with this

Paying overtime correctly calls for accurate calculations, up-to-date knowledge of your sector and flawless payroll admin. That's exactly where we make the difference.

With Recruit:

• Contracts in under 60 seconds - Create trial and temp contracts without the hassle
• Automatic wage calculation - Correct pay in line with current legislation and your Joint Committee
• Dimona and social documents - We handle all the declarations, you focus on your business
• 24/7 personal support - Always a dedicated contact who knows your company
• No fixed monthly costs - Pay only for what you use

Try Recruit or get in touch with our HR experts for tailored advice.

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The information in this article is purely informative and does not replace professional legal or accounting advice. Labour legislation changes regularly. Always consult the current legislation or contact an HR expert for advice tailored to your situation.