Dimona Management, Business Centrum Ghent
Dimona declaration
filed, on time.
The right type.
Monday 08:00. Your employee starts. Dimona must be filed. Without a valid DIMONA declaration, your employee is not officially at work. No covered NSSO contribution. Fine: at least 3,000 euros per employee, day one.
The basics
What is the Dimona declaration and when is it due?
DIMONA stands for Déclaration Immédiate / Onmiddellijke Aangifte (Immediate Declaration). It is the mandatory notification that every Belgian employer must submit to the NSSO before an employee starts working. Not the next day. Not at the end of the week. Before the start.
The declaration consists of two parts: a DIMONA IN at the start of employment and a DIMONA OUT at the end. For hospitality extras you file per day, not per contract. For flexi-jobs per quarter, or per day with an oral contract.
The system is simple in theory. In practice: sixteen types, each with its own timing and rate rules. Choosing the wrong type can break the student quota or cost a flexi-job worker their tax benefit.
Workplace accident without DIMONA
Your workplace accident insurance covers all your employees, even without a DIMONA (art. 49 of the Workplace Accidents Act). But if the declaration is missing at an inspection, the NSSO charges a solidarity contribution of at least 3,674.09 euros per employee (2026) on top of the fine.
Overview
7 of the 16 DIMONA types
Each type has different timing, a different rate and different exceptions. Choosing the wrong type is just as wrong as not filing at all.
| Code | Worker type | Filing timing | What you need to know |
|---|---|---|---|
| OTH | Ordinary workers | Before start of work | The most common. Applies to white-collar and blue-collar workers. |
| STU | Students | Before start of work | Quota of 650 hours/year at solidarity contribution (8.13%). Exceeding = normal rate. |
| FLX | Flexi-jobs | Before the start, per quarter | Worker must have been employed elsewhere for at least 4/5 in T-3, unless retired. Oral contract: one DIMONA per day. |
| PC 322 | Agency workers | Filed by the temp agency | No separate type: the agency files under PC 322, with the user's company number. |
| EXT | Hospitality extras | Per day, before the start of each shift | Maximum two consecutive days with the same employer, otherwise type OTH. |
| IVT | IBO trainees | Before start of training | Individual vocational training in the company. The trainee remains a jobseeker and is not in the DmfA, but does get a DIMONA. |
| ALT | Apprentices | Before start of apprenticeship contract | Apprentices in dual learning, since the 2023-2024 school year. Construction: type RTA. Non-insured interns: type STG. |
Student quota: 650 hours per calendar year
Once a student exceeds the quota of 650 hours, all additional hours are automatically subject to the normal NSSO rate. The employer pays the difference. We actively monitor this quota per student, per year.
The cost of a forgotten declaration
euros on day one
That is the minimum. But day one is rarely the end of the story.
Employee starts, DIMONA missing
Jan Pieters starts Monday at 08:00. The DIMONA was not filed. Jan works. Everything seems normal.
Workplace accident
Jan falls off a ladder. Hospital, surgery, three months of incapacity for work. The workplace accident insurance compensates Jan, but the accident brings the missing DIMONA to light.
Inspection finds repeated violations
The social inspection does not only look at one incident. It checks the pattern. Three employees, two delays per month: that is a structural problem. The fine is multiplied by the number of employees concerned.
NSSO audit: structural problem established
The NSSO links DIMONA declarations to quarterly DmfA declarations. Missing or incorrect declarations over the year are corrected, NSSO contributions are recovered with 7% interest per year. In serious cases a criminal referral follows.
A forgotten declaration. A fine. We make sure this never happens.
Do it yourself or outsource
What DIMONA management entails in practice
If you manage it yourself
Learning the NSSO portal
socialsecurity.be requires registration on the portal, knowledge of the interface and knowing which type to use when.
Determining the type per situation
Is this OTH or STU? Is this flexi-worker also a student? Has he already used up 650 hours elsewhere? You figure it out.
Tracking the student quota
Per student, per calendar year, across all employers. The system only flags an overrun in the notification, after you have declared the hours.
Detecting and correcting errors
An incorrect DIMONA only attracts NSSO attention at the time of an audit. You don't notice it yourself unless you actively check.
Paying fines when you miss something
3,000 to 35,000 euros per employee per incident. More for repeat offences. Plus a solidarity contribution to the NSSO.
With Business Centrum
You send: "Jan starts Monday as a white-collar worker."
We determine the type, check his employment status, file the DIMONA IN and send you a confirmation.
No action required from you for type selection.
We know your workforce. We know whether someone should be OTH, STU or FLX, even in mixed situations.
A student is approaching his 650 hours?
You receive a notification before the quota is exhausted. No surprise on the next month's pay slip.
Error in a declaration?
We detect and correct before the NSSO notices. No fines. No file with the inspection.
DIMONA OUT on termination?
Filed on the same day, linked to the notice procedure. You don't have to think about it.
Edge cases
Where it gets complicated
Most DIMONA errors do not stem from negligence, but from situations that the legislator has indeed foreseen, but which are not covered in a simple manual.
Student reaches 650 hours
His quota is full. What now?
The next performance automatically falls under the normal NSSO rate, even if the student does not inform his employer. You have no choice: either you pay the higher rate, or you take him off the schedule. We signal this before he reaches the limit.
Flexi-worker who is also a student
Which DIMONA type takes precedence?
That depends on the contract you conclude. With a flexi-job employment contract you file a DIMONA FLX: he must then have been employed elsewhere for at least 4/5 in T-3, and those hours do not count towards the student quota. With a student employment contract you file a DIMONA STU. One wrong type and you pay normal NSSO contributions.
Temporary worker becomes permanent employee
Do I have to file a new DIMONA myself?
Yes. The DIMONA filed by the temp agency only covers the temporary period. Once you hire him directly, you file a new DIMONA IN under the correct type for your contract. This is a common mistake: the employer assumes that the agency's declaration is still valid.
Employee starts and finishes on the same day
Is a DIMONA OUT required if he leaves in the evening?
Not if you gave the end date in the DIMONA IN. Otherwise yes: without an end date or DIMONA OUT, the employee is still in service as far as the NSSO is concerned. This has consequences for the quarterly NSSO overview and can, during an audit, lead to discussions about continued employment. Particularly relevant for temporary contracts and agency work.
Sick employee on his first working day
DIMONA IN already filed. He is absent. What now?
The DIMONA IN remains valid and does not need to be withdrawn. The first day of illness is simply registered as absence. What is important: the right to guaranteed wage depends on the employment contract and seniority, not on the DIMONA date. A blue-collar worker is only entitled after one month of uninterrupted service.
Frequently asked questions
Questions about the Dimona declaration
Practical answers to the questions we most frequently receive from employers who wanted to outsource their DIMONA management.
Ask your question directly→Additional services
Read next
- Late Dimona declaration: fines and what to do now
- What is DIMONA and why is it mandatory?
- Social Penal Code sanctions Belgium 2026: higher fines since February, new calculation since September
- What is DmfA? What the return contains, when you file it and what filing late costs
- Employee does not show up for work in Belgium: what to do from day one to dismissal
- Labour inspectorate Ghent: what happens when the East Flanders inspectors call
Sources
Every amount and deadline on this page was checked against these official sources, last consulted on .
- Arbeidsongevallenwet 10 april 1971, art. 49 (Justel); Fedris, Werkgever verzekert zich niet (tijdig)
- Arbeidsovereenkomstenwet 3 juli 1978, art. 52, par. 1, en art. 71 (Justel)
- FOD WASO, bedragen van de administratieve geldboeten
- FOD WASO, flexi-jobarbeidsovereenkomst
- FOD WASO, Wijzigingen aan het Sociaal Strafwetboek vanaf 1 september 2026
- KB 5 november 2002, art. 9, en Sociaal Strafwetboek art. 181 (Justel); RSZ-instructies Dimona
- RSZ, administratieve instructies 2026/3, de gevolgen van een nalatigheid (bijdrageopslag en verwijlintrest)
- RSZ, administratieve instructies 2026/3, Dimona voor gelegenheidswerknemers
- RSZ, administratieve instructies 2026/3, Dimona: welke basisgegevens meedelen (type werknemer)
- RSZ, Administratieve instructies 2026/3, Flexi-jobs
- RSZ, administratieve instructies 2026/3, leerlingen
- RSZ, administratieve instructies 2026/3, studenten
- RSZ, administratieve instructies 2026/3: solidariteitsbijdrage voor nalatigheid van de Dimona-aangifte
- RSZ, administratieve instructies, solidariteitsbijdrage studenten
- Sociaal Strafwetboek, art. 101/1 en art. 181 (Justel); opdeciemen FOD WASO 1 september 2026
Never worry about your DIMONA declarations again
You report who is starting. We file, monitor deadlines, track quotas and correct errors. No fines. No surprises during inspections.
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