Posting a job in Belgium: Dimona, contract, smooth onboarding
From the LinkedIn ad to the first month's payslip: what a Belgian SME must tick to avoid a Dimona infringement, an incomplete employment contract or losing a hire in week 3 due to weak onboarding.
In brief
Hiring in Belgium in 2026 involves six mandatory steps: define the role, publish a compliant ad (GDPR + anti-discrimination), select, get the contract signed before day one, file the Dimona before 23:59 the day before, and onboard structurally. A missing Dimona costs up to 1,600 euros fine per undeclared worker.
Hiring in Belgium in 2026: a 6-milestone journey
For a Belgian SME, hiring an employee remains a structured administrative journey. The 6 milestones we keep seeing at well-organized companies:
Skipping or rushing one of these milestones is costly: NSSO fine, demotivated hire, turnover in month 1-3 (the most expensive for an SME).
A compliant job posting
Writing an ad isn't free-form. Three structural rules:
1. Mandatory mentions. Workplace (at least the municipality), contract type (permanent, fixed-term, temp, student), joint committee, gross salary range (recommended — becomes mandatory in some sectors in 2027 under EU directive 2023/970 on pay transparency). To determine the right joint committee for your company, see our guide on Belgian joint committees for SMEs.
2. Anti-discrimination. The Acts of 10 May 2007 forbid any discriminatory wording (age, gender, origin, marital status). Simple test: replace "junior" with "candidate under 25" — you'd see the problem at once. Prefer "desired experience level" + objective criteria.
3. GDPR. State the CV retention period (12 months max without explicit consent), the controller's identity and the right of access. A serious ATS module does this for you.
Company Belgium's Recruitment module publishes the ad on your site (SEO-friendly /recruitment page), distributes to LinkedIn and Indeed via API, and collects applications in a GDPR-compliant form with auto-acknowledgment.
The employment contract: what must be in it
The contract must be written and signed before the start date (Act of 3 July 1978). Minimum mentions:
- Identity of the parties (employer + employee, BCE and NISS numbers)
- Job title and short description
- Workplace
- Start date and contract type (permanent/fixed-term with end date/temp/student)
- Gross monthly salary + breakdown of benefits (meal vouchers, car, mobile, hospital insurance)
- Applicable joint committee
- Weekly working time and schedule (or reference to work regulations)
- Probation period: abolished for permanent/fixed-term since 2014 (except temp and student)
- Applicable notice (reference to statutory/conventional regime)
For a fixed-term contract, the duration or project must be stated unambiguously — otherwise it requalifies as permanent.
Dimona: the unavoidable formality
The Dimona (immediate declaration) to the NSSO must be filed before the first working day (no later than 23:59 the day before).
- Permanent contract: dimona "IN" at entry, "OUT" at exit
- Fixed-term: dimona "IN/OUT" with start and end dates
- Student: dimona "DIMONA STU" with quarterly quota
- Temp worker: the agency files the dimona, not you
Sanction for a Dimona breach: administrative fine up to €1,600 per undeclared worker, plus arrears on contributions.
The HR → Hires module triggers the Dimona automatically on contract signature (integration with your social secretariat SD Worx, Securex, Acerta, Partena via API). You receive the acknowledgment within seconds, archived in the employee file.
Onboarding that retains hires
Per a SD Worx 2024 study, 22% of new Belgian hires leave within the first 6 months. The top cause isn't salary — it's a failed onboarding.
A serious onboarding fits 3 structured weeks:
Week 1 — Logistics and welcome
- Workstation ready (laptop, email access, badges, phone if needed)
- Tour of the company, introduction to teams
- Documents: work regulations, IT charter, GDPR, remote-work policy
- First lunch with the direct manager
Week 2 — Trade and processes
- Targeted trade training
- Reading current cases
- First supervised assignments
- Weekly check-in with the manager
Week 3 — Gradual autonomy
- Handling a case end-to-end
- Presenting the project to the team
- Day-21 review: what works, what's missing, adjustments
The HR → Onboarding module offers an adaptable checklist per function, with automatic reminders to managers and self-service access for the employee (sign documents, request equipment).
The 3 mistakes to avoid
And after the first payslip?
Payroll is run by your social secretariat, but the HR module centralizes:
- Leave tracking (statutory + seniority + JC)
- Expense claims (with approval workflow)
- Received payslips (manual upload or automatic SD Worx import)
- The employee self-service portal to consult them
The idea isn't to replace your social secretariat — it's to coordinate internal actions (manager → HR → secretariat → NSSO) without losing info along the way. Also read our guide on 7 weekly KPIs to steer a Belgian SME to integrate HR indicators (productivity, compliance) into your leadership dashboard.
Frequently asked questions
When must the Dimona declaration be filed for a new employee in Belgium ?
The Dimona declaration must be filed with the NSSO before the first working day, no later than 23:59 the day before. For a permanent contract you send a Dimona IN at entry and a Dimona OUT at exit. For a fixed-term contract you specify the start and end dates. For a student it is a Dimona STU with a quarterly quota. A missing Dimona triggers an administrative fine of up to 1,600 euros per undeclared worker.
What mentions are mandatory in a Belgian employment contract in 2026 ?
A Belgian employment contract must include the parties' identities with BCE and NISS numbers, job title and short description, workplace, start date and contract type, gross monthly salary and benefits (meal vouchers, car, hospital insurance), applicable joint committee, and weekly working time and schedule. For a fixed-term contract, the duration or project must be stated unambiguously or it requalifies as permanent.
How do you write a compliant job posting in Belgium to avoid discrimination ?
A compliant Belgian job posting must avoid any discriminatory mention related to age, gender, origin, marital status or disability under the Acts of 10 May 2007. Replace junior with an objective experience level and avoid stereotyped descriptions. The ad must state the workplace, contract type, joint committee and ideally the gross salary range. Also include a GDPR notice about CV retention and candidates' right of access.
Why is a 3-week onboarding plan essential to retain new hires in Belgium ?
According to a SD Worx 2024 study, 22 percent of new Belgian employees leave their employer within the first 6 months, and the main cause is a failed onboarding rather than salary. A 3-structured-week plan covers logistics and welcome in week 1, trade training and processes in week 2, and gradual autonomy with a day-21 review in week 3. This plan reduces turnover during the early contract period, the most costly for an SME.