Calculating seniority: impact on pay and dismissal

You have just received a resignation letter from someone who has worked for you for eight years. Or maybe you are the one considering letting someone go. The first question on the table: exactly how much seniority does this person have? Because that number decides almost everything. The notice period, the pay, the severance. One mistake in the calculation and you are looking at a legal problem.

In this article you will learn how to calculate seniority correctly, which periods do and do not count, and what the concrete impact is on pay and dismissal in Belgium. With examples, pitfalls and practical tips.

What exactly is seniority?

Seniority is the total length of uninterrupted employment with the same employer. Sounds simple. In practice, it often is not.

Belgian law actually distinguishes between several types of seniority:

• Company seniority - the total period with the same employer, regardless of role changes. This is the seniority that counts for your notice period.
• Scale seniority - the seniority that sets where you sit on the salary scale of your Joint Committee. The rules for calculating it are laid down in sector-level collective labour agreements (CLAs) and can differ from company seniority.
• Sector seniority - some sectors grant seniority based on your entire career within the sector, not only with your current employer.

That distinction matters. Say you have worked five years in JC 200 (the supplementary Joint Committee for white-collar workers), but the first two years were at a different company in the same sector. Your company seniority is then three years, but your scale seniority can be five years if the JC 200 CLA recognises sector seniority.

Calculating seniority: start date and basic rules

To calculate your seniority correctly, you start from the date of entry into service. That is the first day of your employment contract, not the day you actually start working (although those usually coincide).

The basic rule: count the number of full years and months between your start date and the date on which you want to calculate the seniority. That sounds straightforward, but a few situations make it more complex.

Consecutive contracts with the same employer

Have you had several consecutive employment contracts with the same employer? Think of a fixed-term contract that rolled into an open-ended one. In that case, all contracts count together for your seniority. The start date of the first contract is your reference date.

Concretely: if you started on 1 March 2020 with a six-month contract, followed by a new contract on 1 September 2020, then your seniority begins on 1 March 2020.

Breaks between contracts

This is where it gets legal. If there is a break between two contracts with the same employer, it depends on how long that break lasts and what the reason is.

For short breaks (a few days to weeks) caused by administrative reasons or seasonal work, seniority is usually carried over. For longer breaks, the counter starts again. There is no legally fixed maximum duration for breaks. Case law assesses this on a case-by-case basis, looking at the intention of the parties and the actual circumstances.

This is one of those topics that even experienced HR managers sometimes trip over. The nuances differ from one situation to the next.

Suspension periods that count

Good news (for employees, at least): periods during which your employment contract is suspended still count towards your seniority. That applies, among others, to:

• Illness and incapacity for work (also after the guaranteed salary)
• Annual leave
• Short leave and family leave
• Maternity and paternity leave
• Time credit and thematic leave
• Technical and economic unemployment
• Force majeure (such as the coronavirus period)

In other words: if an employee has been ill for six months, that period still counts in full towards their seniority. That has a direct effect on the notice period if you later proceed to dismissal.

At Recruit, these suspension periods are tracked automatically in the system, so you always have an accurate overview of the real seniority of your employees. Track it manually? You can, but with a team of ten or more employees it quickly becomes error-prone.

Seniority and pay: how scale increases work

This is the key point for many employers and employees. In most Joint Committees, the minimum wages are tied to salary scales that rise based on seniority. The more years of service, the higher the minimum wage.

Salary scales by Joint Committee

Every Joint Committee has its own salary scales. In JC 200 (the largest Joint Committee for white-collar workers), the scales are tied to job classifications and seniority. At each seniority step (often per year or per two years), the minimum scale rises.

Take an administrative clerk in JC 200, category B. The difference between 0 years and 10 years of seniority can quickly amount to several hundred euros gross per month. For the employer, that translates into a proportional rise in labour cost.

Watch out: the rules differ per Joint Committee. In the hospitality sector (JC 302), the scales work differently than in the metal sector (JC 111). Some sectors base their scales partly on professional experience rather than on company seniority alone.

We wrote earlier a detailed guide on calculating labour cost that walks you through the calculation step by step.

What if the wage norm is 0%?

Seniority-based scale increases are always guaranteed, even when the wage norm sits at 0%. For the 2025-2026 period, the maximum margin for labour-cost growth has been set at 0%. But, and this is a common misconception, seniority-based scale increases do not fall under it, and neither do indexations.

In concrete terms: even if you are not allowed to grant an extra pay rise on top of the scale, the automatic increase through seniority goes ahead anyway. For employers, this is a cost you cannot avoid. So budget for it.

Calculating scale seniority

The rules for calculating scale seniority are set out in the CLAs of your Joint Committee. Seniority is often calculated in full months, then divided by twelve and rounded down.

Say you started on 15 March 2022. By 1 February 2026 you have worked 46 full months. Divided by twelve, that is 3.83. Rounded down: 3 years of scale seniority.

Some Joint Committees apply different rules. In certain sectors, professional experience with previous employers is (partly) counted. In others, the counter only starts after a trial period or entry period. Always consult the specific CLA of your JC for the exact rules.

Seniority and notice period: the direct link

Of all the consequences of seniority, the impact on the notice period is perhaps the most tangible. The longer someone has been employed, the longer the notice period when the employer dismisses them.

The single status since 2014

Since 1 January 2014, Belgium has applied the single status. That means blue-collar and white-collar workers have the same notice periods for seniority built up from that date. For seniority from before 2014, transitional rules apply (the so-called Part I and Part II of the notice period).

You will find more on the specific rules in our article on calculating notice periods.

Notice period for employer-initiated dismissal

The notice period is expressed in weeks and rises as seniority increases. A few reference points:

• 0 to 3 months of seniority: 1 week
• 3 to 6 months: 3 weeks
• 6 to 12 months: 4 weeks
• 12 to 15 months: 5 weeks
• 2 years: 8 weeks
• 5 years: 18 weeks
• 10 years: 30 weeks
• 15 years: 39 weeks
• 20 years: 60 weeks
• 25 years: 75 weeks

From 2025, Part II of the notice period (the part covering pre-2014 seniority for higher-level white-collar workers) has been raised to 36 weeks. A detail you easily miss if you are not actively keeping up with it.

Notice period when the employee resigns

When the employee resigns themselves, the notice periods are considerably shorter and capped at a maximum of 13 weeks, regardless of seniority. That cap has applied uniformly to all employees since late 2023.

Severance pay

Do you, as the employer, opt for dismissal with immediate effect (without serving the notice period)? Then you owe severance pay equal to the salary for the duration of the notice period. For an employee with 20 years of seniority, that means 60 weeks of pay. That is a hefty bill.

One day of seniority can sometimes make the difference between a notice period of, say, 30 or 33 weeks. That is why an accurate calculation of years of service is essential. In our experience with thousands of temporary employees, we see that employers who do not track seniority precisely end up with unpleasant surprises at dismissal.

Seniority, year-end bonus and other benefits

Seniority reaches further than pay and notice period alone. Several supplementary benefits and statutory bonuses are directly or indirectly tied to it.

Year-end bonus (thirteenth month)

In many sectors, the year-end bonus is calculated based on the number of months worked in the calendar year. But the amount itself is often tied to the scale, which in turn rises with seniority. More years of service means a higher scale, and therefore a higher year-end bonus.

Some CLAs also provide an extra seniority supplement on top of the year-end bonus. In JC 124 (the construction sector), for example, there is a loyalty bonus that rises with years of service.

Holiday pay

Statutory holiday pay (both single and double) is calculated based on the salary. Since the scale rises with seniority, holiday pay indirectly rises too. For white-collar workers, the double holiday pay amounts to 92% of the gross monthly salary, so a higher scale automatically results in more holiday pay.

Seniority leave

Some sectors and companies grant extra leave days based on seniority. In JC 200, employees are entitled to one or more extra holiday days after a certain number of years. This is not a statutory obligation but a sector-level or company arrangement.

Seniority bonus

Certain sectors provide a one-off bonus on reaching a given level of seniority. Think of 25 years of service. The conditions and amounts are set out in the sector-level CLAs.

Seniority in a takeover or merger: CLA 32bis

What happens to employees' seniority when a company is taken over or merges? Employees keep their full seniority, which transfers automatically to the new employer. This is a question we regularly get at Recruit from employers involved in a takeover.

The answer lies in CLA 32bis, the collective labour agreement on the transfer of undertakings.

The basic principle

In a transfer of undertaking by agreement (sale, merger, demerger), all rights and obligations under the employment contract pass automatically to the new employer. That explicitly includes seniority.

Concretely: if an employee had 12 years of service with employer A and the company is taken over by employer B, then that employee keeps their 12 years of seniority. The new employer cannot "reset" that seniority.

What falls under CLA 32bis?

The transfer must take place "by agreement". That includes, among others:

• Sale of a business
• Merger or absorption
• Transfer of a company division
• Outsourcing of an activity (under certain conditions)

In the event of bankruptcy, different rules apply. CLA 32bis is then not automatically applicable, although in a takeover after bankruptcy the acquirer is sometimes required to take on part of the staff with (partial) retention of seniority.

Practical consequences

For the acquiring employer, this means you must take into account the full seniority of the transferred employees, both for the pay (scale), the notice periods, and all other seniority-linked benefits.

We wrote earlier about the legal aspects of employment contracts in Belgium. In a takeover too, those contractual rights remain intact.

Temp workers' seniority when hired permanently

A special case that raises many questions in practice: what if you hire a temp worker permanently? Does the agency period count towards seniority?

The "inflow" reason

Since the introduction of the fourth reason for temporary agency work, "inflow", there is a clear framework. Inflow means that a temp worker is employed by a user with a view to permanent recruitment.

Strict rules apply to inflow:

• A maximum of three consecutive attempts (three different temp workers) per vacant position
• A maximum of six months per temp worker
• Total duration of inflow limited to nine months per position

And here is the crucial point: if you permanently hire the temp worker after the inflow period with an open-ended contract, then the inflow period counts towards seniority.

Other reasons for agency work

With the classic reasons (replacement, temporary increase in work, exceptional work), the agency period does not, in principle, automatically count towards seniority when the worker is later hired permanently. Unless the parties agree otherwise or the court rules that there was in fact a disguised permanent employment.

After more than 15 years in Belgian payroll, we know exactly how sensitive this point is. Employers who work for years with the same agency workers without hiring them permanently run the risk that a court rules that a de facto open-ended employment contract existed. With all the consequences for the seniority calculation.

You will find more on the rules around temporary staff in our guide on the dismissal procedure for employers.

Seniority disputes: when things go wrong

Disputes over seniority happen more often than you would think. Often only at the moment of dismissal, when employer and employee disagree on the exact number of years of service.

Common points of dispute

• Unclear start date - Especially with verbal arrangements or informal trial periods. Without written proof, discussion arises.
• Breaks between contracts - Does a two-week break count as a real break? Or does seniority carry on? The assessment depends on the specific circumstances.
• Transition from temp worker to permanent - Employees claim their agency period counts, employers contest it.
• Employment through different companies - If you work for company A and company B that share the same shareholder, does that count as the same employer?

How to avoid disputes

The honest truth? Most disputes can be avoided with good administration.

• Set the start date in writing in the employment contract
• Keep a file of all consecutive contracts
• Document breaks and the reason for them
• Keep a history of role changes and pay rises

With a payroll system like Recruit, this is tracked automatically. Every change in the contract, every suspension period, every salary-scale adjustment is logged. At dismissal, you then have a watertight overview of the full seniority.

Common mistakes when calculating seniority

In our experience with thousands of temporary employees, we see a number of mistakes come back time and again:

Forgetting the trial period. The trial period (which in Belgium, by the way, was abolished in 2014 for most contracts) counted in full towards seniority. Employers still working with older contracts sometimes forget this.

Not counting suspension periods. Long-term illness, parental leave or time credit suspend the employment contract but do not interrupt seniority. An employee who has been ill for two years has, on return, the same seniority as if they had kept working.

Using the wrong seniority. Company seniority and scale seniority are not always the same. The notice period is calculated on company seniority, the pay on scale seniority. Do not confuse them.

Misreading the dismissal date. Seniority is calculated up to the date on which the notice period ends, not up to the date of the resignation letter. That can make weeks or months of difference.

Not accounting for the single status. For employees who started before 2014, you must calculate the notice period in two parts. Part I for seniority from 2014, Part II for the period before. Since 2025, Part II has been raised to a maximum of 36 weeks.

In short

Calculating seniority looks simple, but the details make the difference. Know which type of seniority you need (company, scale, sector), count all suspension periods, and account for the specific rules of your Joint Committee.

The impact is real: on your pay through scale increases, on your notice period at dismissal, on your year-end bonus and holiday pay, and even in a takeover of the company. One mistake in the calculation can make thousands of euros of difference.

Want to know more about the specific notice rules? Read our article on calculating notice periods. And for a complete overview of your staff costs: check out our guide on calculating labour cost.

Frequently asked questions

Does illness count towards my seniority? Yes. All periods of suspension of the employment contract, including illness, incapacity for work and time credit, count in full towards your seniority. You lose no years of service by being ill.

What if I worked through a temp agency before being permanently hired? That depends on the reason. Under inflow (the fourth reason for temporary agency work), the agency period counts. Under other reasons such as replacement or temporary increase in work, in principle it does not, unless agreed otherwise.

Do I keep my seniority in a takeover of the company? Yes. Under CLA 32bis, your full seniority transfers automatically to the new employer in a transfer of undertaking by agreement. The new employer cannot reset your seniority.

How do I calculate the seniority of an employee who started before 2014? For the notice period you calculate two parts: Part I based on seniority from 1 January 2014, Part II based on the seniority from before that date. Since 2025, the maximum for Part II is 36 weeks in the case of dismissal by the employer.

Is seniority the same as professional experience? Not necessarily. Seniority refers to the period with the same employer (or in the same sector, depending on the context). Professional experience covers your entire career. Some Joint Committees count professional experience partly towards the salary scale, but that is sector-specific.

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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. Note: the rules can differ per Joint Committee and sector.