Indexo School
Indexo School for teachers
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A ready-to-use lesson on the payslip: the ‘from gross to net’ lesson, a worksheet of 6 exercises and its answer key, calculated by the Indexo engine with the rules in force on 1 October 2026.
Free, with no sign-up and no ads. Pupils have nothing to create: no account, no data sent.
Objectives
- Read a payslip: gross pay, deductions, net pay.
- Understand what social security contributions and withholding tax (bedrijfsvoorheffing / précompte professionnel) are for.
- Know why two people on the same gross pay do not get the same net pay.
Suggested lesson plan (50 minutes)
- 10 minutes: start from a question, ‘€2,500.00 gross: how much is that net?’, and note down the class’s answers.
- 15 minutes: go through the lesson on the board, step by step.
- 20 minutes: pupils do the worksheet, alone or in pairs, at the chosen level.
- 5 minutes: correction with the answer key below, and a look back at the answers from the start.
The worksheet and its answer key
Choose the level, then ‘Printable version’. Pupils can also do the exercises online, on the lesson page.
The tool could not be displayed. Reload the page (Cmd + Shift + R on a Mac, Ctrl + F5 on a PC).
Frequently asked questions
For what age?
The beginner level is suitable from the end of lower secondary; the full level, in upper secondary and in adult education (enseignement de promotion sociale).
Can I project the page in class?
Yes. Nothing is installed or saved: the page and its exercises run in the browser.
What next?
- The gross-to-net lessonThe six steps, to go through with the class.
- Translate my payslipFor immersion classes: the terms in Dutch, German and English.
- Payroll glossaryThe terms explained simply.
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.