Every month you send your social secretariat the data it uses to calculate wages: Dimona changes, hours worked and absences, overtime, the number of meal vouchers and mobility data. The more complete and timely that data is, the fewer corrections you pay for afterwards.
There is no official list that applies to every social secretariat. Each secretariat works with its own codes, forms and closing dates. The legal rules behind the data are the same everywhere, though, and that is exactly where things often go wrong.
Companies with staff on the road or on site feel this most. Hours arrive on paper, in messages or in separate lists, and a forgotten overtime hour or a sick day without a certificate only surfaces once the payslip has gone out. What pre-payroll actually means is explained in our article on pre-payroll software; this article is about the concrete monthly submission.
In this article you will read what to check and submit every month, which 2026 rules apply to overtime and meal vouchers, what an error with the NSSO costs and which routine to follow in the week before closing.
What do you have to send your social secretariat every month?
The table below gives a practical overview. Agree the exact timing with your secretariat, because the closing date differs per secretariat and sometimes per joint committee.
| What | Deadline or timing | Typical error | Consequence |
|---|---|---|---|
| Dimona IN and OUT | IN before work starts, OUT no later than the first working day after the end | A student or flexi worker starts before the declaration | Solidarity contribution on inspection and loss of the NSSO advantage |
| Hours worked per day | At month-end closing, ideally tracked weekly | Hours estimated or retyped afterwards | Wrong pay and a correction on the next payslip |
| Absences with a reason | As soon as the absence is known, with a certificate before closing | Sickness booked as leave or without a certificate | Wrong guaranteed pay or a dispute with the employee |
| Overtime and type of overtime | At month-end closing, with the written agreement at hand | Voluntary and ordinary overtime not separated | Too much or too little social security and withholding tax |
| Meal vouchers | Based on the days actually worked in the month | Vouchers granted for public holidays or sick days | Too many or too few vouchers, to be corrected later |
| Mobility and expenses | Together with the hours, approved by the manager | Kilometres without a date or destination | Allowance hard to justify during an inspection |
Note: this is an overview from practice, not an official list. Ask your secretariat which codes and attachments it expects, for example for bonuses, advances or wage garnishment.
When must the Dimona IN and OUT be filed?
The Dimona is the immediate declaration of employment to the NSSO. You file the Dimona IN before the employee starts working. The Dimona OUT follows no later than the first working day after the employment relationship ends. In case of dismissal for serious cause, you file it during the working day after the dismissal.
If the Dimona is missing during an inspection, you risk a solidarity contribution of three times the basic contributions, calculated on the guaranteed average minimum monthly income, with an indexed minimum amount. For students and occasional workers without a timely Dimona, the favourable social security scheme is also lost.
In practice: only let a new employee start once the Dimona IN is confirmed, and keep contract end dates in a fixed monthly list so that no OUT is forgotten.
Which hours and absences do you report?
Your secretariat needs the hours worked per employee and per day, with the right code for every absence. Think of holidays, sickness, short leave, compensatory rest, public holidays and temporary unemployment. Every code affects pay, meal vouchers and the DmfA, the quarterly declaration to the NSSO.
- Every working day has hours worked or an absence code, with no empty days.
- Sick days have been reported and the certificate is on file where your rules require it.
- Leave has been approved and matches the employee's balance.
- Hours on a site or assignment are booked to the right project.
- Deviations from the schedule have been confirmed by the manager before closing.
General mandatory working time registration is planned from 2027, but no law has been adopted yet. Read in our article on time registration in 2027 what has been settled and what is still open.
How do you report overtime under the 2026 rules?
Since 2026, broader voluntary overtime exists alongside ordinary overtime. So for every overtime hour, report not only the number but also the type.
Ordinary overtime
Work beyond 9 hours a day or 40 hours a week entitles the employee to overtime pay: 50% on weekdays and Saturdays, 100% on Sundays and public holidays. In principle, compensatory rest within the reference period applies. The so-called internal limit, the maximum number of hours an employee may build up above their average working time, is 143 hours.
Voluntary overtime since 1 April 2026
- An employee may work up to 360 voluntary overtime hours a year, or up to 450 in hospitality with a registered cash system.
- Of these, 240 (hospitality: 360) are gross = net: no overtime pay, no social security and no tax.
- Voluntary overtime does not require compensatory rest.
- The employee agrees in writing in advance. That agreement is valid for one year, is renewed tacitly and can be ended with one month notice.
For the remaining voluntary overtime hours, 120 according to the draft texts, overtime pay, social security and withholding tax are due. That point still needs to be confirmed against the final legal text. In addition, the tax-favourable overtime scheme has been raised permanently from 130 to 180 hours a year as of 1 January 2026.
So report per employee: the number of overtime hours, whether they are ordinary or voluntary, the date and whether a valid agreement exists. This prevents the annual quota from being exceeded unnoticed.
How many meal vouchers and which mobility data do you report?
You grant one meal voucher per day actually worked. Public holidays, compensatory rest, sickness, holidays and temporary unemployment do not count. Only companies with different work schedules may calculate on the basis of hours: hours worked divided by the normal daily working time. That method must be laid down in a collective labour agreement or the work regulations.
Since 1 January 2026 a meal voucher may be worth at most 10 euros, with an employer contribution of at most 8.91 euros and an employee contribution of at least 1.09 euros. The increase is not automatic: it requires a collective labour agreement or an annex to the employment contract. So report a new value in time, together with that document.
Mobility data
What you submit for mobility varies widely by company and by sector: commuting, business trips with kilometres or allowances from a sector agreement. What always helps: for each trip a date, departure and destination, the number of kilometres and an approval. Without those details an allowance is hard to justify.
What do errors in payroll preparation cost?
Errors in the monthly data end up in the DmfA. That quarterly declaration must reach the NSSO by the last day of the month following the quarter. According to the NSSO administrative instructions (2026/3), the following sanctions apply, among others:
- Late DmfA: a flat-rate fee of 495.79 euros, increased when contributions are high.
- Correction ex officio: if the NSSO corrects an incomplete or incorrect declaration after an inspection, it costs 50 euros plus 4 euros per missing or changed employment line.
- Late payment: a contribution surcharge of 10% and late-payment interest of 7% a year.
- Limitation period: social security contributions in principle become time-barred after 3 years; in case of fraud or deliberately incomplete declarations, this has been 10 years since 1 January 2023.
An error made today can therefore still lead to a bill years later. On top of that comes the hidden cost: corrections, extra payslips and questions from employees. Read in this article on deviations confirmed too late why payroll becomes more expensive as a result.
Which routine helps in the week before closing?
A fixed routine prevents everything from piling up on the last day. Plan these steps in the five working days before your secretariat's closing date:
- Day 1: check new starters, leavers and contract changes, and whether every Dimona IN and OUT has been confirmed.
- Day 2: look for empty days, missing check-ins or check-outs and hours without a project, and ask the people involved to complete them.
- Day 3: approve leave, sickness with a certificate, expenses and kilometres, or ask for clarification.
- Day 4: test overtime by type against the annual quota and the written agreement, and count the meal vouchers per day worked.
- Day 5: have a second person run spot checks, send the data and note what you still need to follow up after closing.
If a correction still comes in after closing, process it in the following month and note the cause. After a few months you will see which errors keep recurring.
How MyVIRO helps
MyVIRO collects the data for your monthly submission where it is created. Employees check in and out, register hours per site or assignment, request leave, report sickness with a photo of the certificate and enter expenses and kilometres, all in one app for iOS and Android.
In the back office you immediately see, before payroll preparation, which check-ins are missing, which locations deviate and which requests are still open. The validated data flows to your HR, ERP or payroll system, or to VIRO for pre-payroll. MyVIRO does not calculate wages itself; that remains the job of your social secretariat or payroll system.
- See how MyVIRO works, from check-in to full ESS
- Read what MyVIRO for companies delivers in practice
- Discover VIRO for pre-payroll as the next step after registration
Request a demo and see how your month-end closing becomes faster with fewer corrections.
Read also
- Management by exception: checking time records and payroll for deviations
- Is travel time working time? How to record mobility correctly for payroll
- Reporting sick via an app: when is a medical certificate required in 2026?
Frequently asked questions about payroll preparation
No. Each secretariat works with its own codes, forms and closing dates. The underlying rules, such as those for Dimona, overtime and meal vouchers, are laid down by law.
No later than the first working day after the employment relationship ends. In case of dismissal for serious cause, it is filed during the working day after the dismissal.
Since 1 April 2026 up to 360 a year, or 450 in hospitality with a registered cash system. Of these, 240 (hospitality: 360) are gross = net, provided the employee agreed in writing in advance.
No. Meal vouchers are granted per day actually worked, so not for public holidays, compensatory rest, sickness, holidays or temporary unemployment.
The NSSO charges a flat-rate fee of 495.79 euros, increased when contributions are high. If the contributions are also paid late, a 10% surcharge and late-payment interest of 7% a year follow.
In principle up to 3 years after the facts. In case of fraud or deliberately incomplete declarations, up to 10 years since 1 January 2023.
No. MyVIRO collects and validates hours, absences, expenses and mobility. Wage calculation stays with your social secretariat or your own payroll package.
Sources
- NSSO, DmfA administrative instructions 2026/3 on late declaration and late payment of contributions (in Dutch), on socialsecurity.be
- NSSO, Limitation period for social security contributions (in Dutch): socialsecurity.be
- FPS Employment, Labour and Social Dialogue, Working time and reduction of working time (in Dutch): werk.belgie.be
- Forum for the Future (in Dutch), on voluntary overtime, social security and tax and on the increase to 180 tax-favourable overtime hours
- Lexgo, Meal vouchers: maximum value rises to 10 euros from 1 January 2026 (in Dutch): lexgo.be
Author: Jean-Philippe Delberghe at MyVIRO. Published on 23 October 2026. Last updated on 23 October 2026.
This article is an informative explanation and not legal advice. Consult your social secretariat for your specific situation.