Understand · Official documents
Decode an official document: tax assessment notice, tax form 281.10, holiday pay and contributions
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Four documents come round every year: your employer’s tax form 281.10 (fiche 281.10), sent by the end of February at the latest; the tax assessment notice (aanslagbiljet / avertissement-extrait de rôle) from FPS Finance, which calculates your tax; the holiday pay statement for blue-collar workers; and the social contributions notice for the self-employed. For each one, Indexo explains every amount and compares it with its own simulation.
Copy the amounts from your document, or drop in the PDF of your tax form 281.10: it is read in your browser and never sent.
Which document do you want to understand?
- Tax assessment noticeThe final calculation of your tax: why you pay extra or get a refund.
- Tax form 281.10The tax summary of your year’s pay, to copy into your tax return.
- Holiday pay statementBlue-collar workers’ holiday pay, calculated on the previous year’s wages.
- Social contributions noticeA self-employed person’s quarterly contributions, then their adjustment.
| Document | Sent by | What to check |
|---|---|---|
| Tax assessment notice | FPS Finance | Taxable income, reductions, municipal tax, withholding taxes, balance and deadlines. |
| Tax form 281.10 | Your employer | Pay (code 250), withholding tax (286), special contribution (287), work bonus (284). |
| Holiday pay statement | ONVA/RJV or holiday fund | Gross pay raised to 108%, equivalent days, deductions, withholding tax, net. |
| Social contributions notice | Social insurance fund | Reference income, rate, minimum, management fees, adjustment. |
How Indexo checks a document
- Every amount is explained: where it comes from, which rule applies, with the official source.
- Indexo redoes the calculation with the same engine as the salary calculator and the tax simulator.
- Discrepancies are flagged, with the most common reasons and what to do next (employer, fund, FPS Finance).
Nothing is sent or saved: the amounts and files stay in your browser.
Frequently asked questions
Are my documents sent to Indexo?
No. The amounts you copy and the PDFs you drop in are read in your browser. Nothing is sent or saved.
What if an amount is wrong?
Contact whoever drew up the document: your employer or its social secretariat for tax form 281.10, the ONVA/RJV or the holiday fund for holiday pay, your social insurance fund for contributions, FPS Finance (objection within the year) for the tax assessment notice.
And my monthly payslip?
It has its own tool, Check my payslip, which also reads PDFs and photos.
What next?
- Check my payslipEvery line of your monthly payslip, recalculated.
- Household tax simulatorHousehold tax, line by line.
- Annual pay reviewYour 12 payslips compared with tax form 281.10.
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.
- Période imposable et avertissement-extrait de rôle (updated on 8 January 2026), Wikifin (FSMA) (secondary source).
- Fiches fiscales 2021 : explication de la fiche 281.10, zone par zone (updated on 30 April 2021), FPS BOSA. Cross-checked with: a tax form 281.10 for 2024 (codes 250, 252, 254, 286 and 287).
- Calcul du pécule de vacances des ouvriers (2026 amounts), ONVA/RJV.
- Comment ma cotisation sociale trimestrielle est-elle calculée ?, UCM (secondary source).