Understand · The calculation
Indexo School: understanding your payslip
Updated on
Short lessons and marked exercises to understand how €2,500.00 gross becomes €2,175.62 net on a Belgian payslip. Each answer is calculated by the Indexo engine, with the rules in force on 1 October 2026.
For secondary school pupils, students and anyone receiving their first payslip. Free, with no sign-up: nothing is sent or stored.
The lessons
- From gross to net, in six steps: social security contributions, work bonus, withholding tax (bedrijfsvoorheffing / précompte professionnel), special contribution, with marked exercises.
- The payslip explained: every line of a real payslip, with an example.
- Translate my payslip: payroll words in Dutch, German and English.
- The payroll glossary: terms explained simply.
For teachers
A worksheet of 6 exercises, with the answer key, to print for the class: Indexo School for teachers. The answer key updates itself when the scales change.
What next?
- From gross to netThe lesson and the marked exercises.
- For teachersThe worksheet and its answer key, to print.
- First jobContract, payslip, tax: what changes with your first salary.
Sources
Parameters in force on 1 October 2026. Each parameter links to its source, the official one where it exists; a secondary source is flagged as such.
- Instructions administratives : les cotisations de sécurité sociale, NSSO. Cross-checked with: UCM, Securex and the FEB (via the Walloon Public Service) for the basic employer rate in the private sector: 19.88% basic contribution and 5.12% wage moderation contribution, making 25%.
- Calcul du précompte professionnel : annexe III de l’AR/CIR 92 et formule-clé 2026, FPS Finance.