A payroll provider in Belgium calculates your wages and files your social security returns with the NSSO (in Dutch: RSZ) as your mandatary. There are six types, and only the 25 recognised social secretariats on the official list of 20 June 2025 may collect your contributions; in 2025, 83% of employers were affiliated with one. Whichever type you choose, you remain the employer and remain responsible for what is filed in your name.
The six types of payroll provider in Belgium
The word "payroll provider" covers very different players. The NSSO recognises two kinds of mandatary for your returns: the recognised social secretariat and the social service provider without recognition. Around them sit four other models.
| Type | Legal position | Collects your NSSO contributions? | Who files Dimona and DmfA? | Fits when |
|---|---|---|---|---|
| 1. Recognised social secretariat | non-profit association recognised by the Minister of Social Affairs, on the list in the Belgian Official Gazette | yes, exclusive right | the secretariat, as your mandatary | you want one party for calculation, returns and payment of contributions |
| 2. Social bureau working with a recognised secretariat | local office, not recognised itself; the secretariat behind it is | yes, through that secretariat | the secretariat behind the bureau | you want a fixed contact nearby who does the work for you |
| 3. Social service provider without recognition | mandatary registered with the NSSO, not recognised | no, you pay the NSSO yourself | the service provider | you want a lean calculation service and handle payments yourself |
| 4. Accountant or bookkeeper | can act as a service provider registered with the NSSO, or passes your data to a secretariat | no | depends on the set-up: ask | your payroll is small and tied to your bookkeeping |
| 5. Payroll software, you do it yourself | no mandatary; you are your own administrator | no, you pay yourself | you, through the social security portal | you have in-house payroll knowledge and time |
| 6. International payroll or employer of record | foreign or Belgian company; an employer of record becomes the legal employer | only via a Belgian partner that is a recognised secretariat | the local partner, or the employer of record for its own staff | you hire in several countries without your own entity, after a legal check |
Type 2 is a model in its own right: a social bureau is not a secretariat, but works with one that files the returns and collects the contributions. What exactly a social bureau is, and how it differs from the secretariat itself, is explained in a separate guide. Whether you are obliged to use any of them at all is answered in is a social secretariat mandatory: it is not.
What a payroll provider in Belgium may do, and what it may not
Collecting contributions is reserved. According to the NSSO administrative instructions, recognition gives a social secretariat the exclusive right to collect the social security contributions owed by its affiliated employers. A service provider without recognition may not use the title social secretariat and may not collect contributions the way a recognised secretariat does. With a type 3 provider, you transfer the contributions to the NSSO yourself.
Recognition comes with a guarantee. The Royal Decree of 28 November 1969 (article 48) obliges every recognised secretariat to deposit a guarantee with the National Bank or the Deposit and Consignment Office: from € 37,184.03 to € 185,920.14, depending on the number of workers of its members. That guarantee covers claims of affiliated employers who suffer damage because the secretariat failed to transfer or pay the amounts owed to the NSSO. A secretariat must also work with an independent registered auditor who supervises its financial operations. A non-recognised provider has none of these obligations.
Quality is measured. The NSSO inspection checks secretariats with a quality barometer over 6 control domains. It can include non-recognised providers too, except for the financial checks. To be recognised, a secretariat must group at least 300 employers, among other conditions.
The mandate is registered. Every mandatary acts in its own name on your behalf and is, in the words of the NSSO, the first point of contact for the social security institutions. The mandate is made known to the NSSO and recorded in Mahis, the NSSO application in which you can also see your own mandates. What a recognised secretariat is under the law, and how you look one up, is set out in recognised social secretariat or social bureau.
What always stays with you as the employer
Handing over the work does not hand over your role. Four things stay with you whatever contract you sign.
- Final responsibility for the returns. The NSSO writes it plainly on its Dimona pages: even if your social secretariat files your Dimona returns, you remain the party with final responsibility for them. A Dimona that goes out too late is your fine, not your provider's.
- Correct and timely data. Your provider calculates with what you send. Hours, absences, new hires and leavers before the cut-off date are your job.
- Payment. You pay the net wages to your employees. Contributions that are not paid on time carry a surcharge of 10% and late-payment interest of 7% a year. NSSO claims on employers become time-barred after 3 years, so an error can come back long after the month it happened.
- Your employees' personal data. Under the GDPR you stay the controller and your payroll provider is the processor. The European Commission uses exactly this example: a company that signs a contract with a payroll company is the controller, the payroll company is the processor, and the processor's duties "must be specified in a contract or other legal act".
What to do when a provider does make a mistake, and who pays for it, is covered in a mistake by your social secretariat.
How payroll processing via a payroll provider works
The monthly cycle looks the same with almost every provider. Only the split of the work differs.
- You send the variables. Hours worked, overtime, sickness, leave, new employees and leavers. A provider sets a cut-off date for this each month.
- The provider calculates. Gross pay under your joint committee, the employee's social security contribution, the withholding tax and the net pay. You receive the payslips and a summary of what goes to whom.
- You pay. The net wages to your employees on the pay date. Through a recognised secretariat, the contributions go to the secretariat, which transfers them to the NSSO.
- The returns go out. A Dimona for every new employee at the latest when the employee starts work, and every quarter the DmfA, which must reach the NSSO within 1 month after the end of the quarter. The withholding tax return goes to the FPS Finance, monthly as the rule.
- Once a year. Tax forms 281.10, the holiday certificate, indexation and the bonuses of your sector.
With a social bureau, steps 1 and 2 shift: you send the variables by e-mail or form, and the bureau collects and checks them.
How to check a payroll provider in Belgium before you sign
Eight checks. Each one can be answered with a document, not with a promise.
- Recognition number. Ask for the number and look it up on the list of recognised social secretariats in the Belgian Official Gazette. A recognised secretariat must state on all its documents its name with "VZW - Sociaal Secretariaat", its recognition number and the date of the ministerial decree. Acerta, for example, is on the list under number 250. Our list of the largest social secretariats shows all numbers.
- The mandate. For a social bureau or an accountant: which secretariat files your returns, or are they a service provider themselves? Check afterwards in Mahis who holds your mandate.
- Your joint committee. Ask which clients in your sector they handle and how they follow indexation and sector bonuses. Not sure of your own committee? Look up your joint committee first.
- Cut-off and pay dates. Until which day can you send changes, and on which day are payslips ready? A cut-off that is too early forces you to pay corrections the next month.
- Processor agreement under the GDPR. Ask for it before you sign, with the list of subprocessors and what happens to the data when the contract ends.
- Pricing model. Per payslip, per employee, per month or a package. Ask what is extra: contracts, students, certificates, advice. Our guide to the cost of a social secretariat shows how prices are built.
- Notice period and contract term. Many contracts run for several calendar years and end on 31 December after six months' notice. Read the notice period of a social secretariat before you sign anything.
- Transfer of history. Who requests the history from your current provider, and who checks it? Under the NSSO instructions, the outgoing mandatary must inform the new one about the quarters it filed and provide the information needed for the technical transactions.
Scorecard: compare payroll providers in Belgium
Give each criterion a weight from 1 to 3 that fits your company, score each provider from 0 to 2, multiply and add up. The provider with the highest total is your best match, not necessarily the cheapest.
| Criterion | Question you ask | 0 points | 2 points |
|---|---|---|---|
| Legal position | Recognised, with a recognised partner, or service provider? | no clear answer | number checked on the official list |
| Contributions | Who collects and transfers them? | unclear | in writing, with the route of the money |
| Your joint committee | Which employers in your sector do they handle? | none | several, and they explain your sector rules on the spot |
| Contact | Who do you call, and how fast do they answer? | general line | named person who knows your file |
| Work on your side | What do you still enter yourself each month? | everything in a portal | you send the variables, they do the rest |
| Cut-off and pay dates | Until when can you change, when are payslips ready? | early cut-off, no exceptions | cut-off that matches your pay date |
| GDPR | Is there a processor agreement? | no | yes, with subprocessors listed |
| Price | What is included, what is extra? | price per payslip only | annual price for your real staff |
| Exit | Term, notice, transfer of history? | long term, no transfer clause | clear term and written transfer |
A quick way to set the weights: an SME without an HR person gives "contact" and "work on your side" a 3. A company with an in-house HR team gives "software" and "reporting" more weight and adds them as rows. A foreign company first reads the decision path below.
Decision path in four questions
- Does your company have an entity or establishment in Belgium? No: read foreign employer in Belgium before choosing anything.
- Do you want to do the calculation and the returns yourself? Yes, and you have the knowledge: software (type 5). No: go to question 3.
- Do you want one party that also collects the contributions? Yes: a recognised secretariat (type 1) or a social bureau that works with one (type 2). No: a service provider (type 3), and you pay the NSSO yourself.
- Do you want to do the data entry yourself in a portal, or hand it over? Portal: directly with a secretariat. Hand it over: a social bureau with a fixed contact. The differences per task are set out in Acerta or Business Centrum.
Employer of record and international payroll providers in Belgium
International providers sell two things. Global payroll means one contract for payroll in many countries, carried out in Belgium by a local partner. You remain the employer. Ask which Belgian secretariat or provider files your returns, and apply the eight checks above to that partner.
An employer of record goes further: it becomes the legal employer of your staff and invoices you. Belgian law, article 31 of the Act of 24 July 1987, forbids placing workers at the disposal of a user who exercises any part of the employer's authority over them, outside the exceptions the law allows, such as temporary agency work. Have any employer of record construction checked before you sign. The difference with being the employer yourself, with a local partner for payroll, is explained in employer of record in Belgium.
Who are the largest payroll providers in Belgium?
There is no official ranking by company size, and we do not publish one. The official list of 20 June 2025 counts 25 recognised social secretariats with an active head office. Their number of clients, payslips and offices is only published by the secretariats themselves. We collected those figures, with source and date, in the largest social secretariats in Belgium, and compared the five best known in Acerta, SD Worx, Securex, Liantis and Partena compared.
Size by itself answers a different question from yours. For an SME with five employees, the contact person and the work left on its side weigh more than the number of offices. For a midmarket company with several sites and joint committees, the depth of sector knowledge and the reporting decide. For a large company, the integration with its HR systems and the audit trail come first. Use the scorecard with those weights.
Switching to a new payroll provider
A mandate passes to a new mandatary only at the start of a new quarter. The new provider can still register it in Mahis up to 1 month after the start of the current quarter; further back is not possible. Your current contract usually decides the date, through its term and notice period. The full route, with the last DmfA and the transfer of your files, is in changing social secretariat.
Business Centrum: a social bureau in Ghent that works with Acerta
Business Centrum is a type 2 provider: a social bureau in Ghent, founded in 2013 and a recognised partner of Acerta. Acerta, recognised under number 250, files the returns and collects the contributions. We handle the communication and the processing through Acerta, with one fixed contact who knows your file. When you switch, we request your historical data from your previous secretariat and check it. We do not publish rates: you get a quote after a conversation about your file. How the work is split is described on social bureau with Acerta and in our payroll administration service. Want to see whether this model fits your company? Ask us to call you back.