How does a suppletie work?
The obligation is in Article 10a of the Dutch General State Taxes Act (AWR) and is worked out for VAT in Article 15 of the VAT Implementing Decree 1968 (Uitvoeringsbesluit omzetbelasting 1968). The core is your own finding: it is about what you discover, not about what the Belastingdienst (the Dutch tax authority) finds. As soon as you know, you must report.
Since 1 January 2025 the deadline is no longer vague. If you find that you reported and paid too little VAT, you must file the suppletie within eight weeks of that moment. The starting point is your own finding, and with that the moment you discover it has become meaningful for tax. In addition, the reporting obligation looks back five calendar years: an error from an older period within that window must still be reported, even if you only find out years later.
The threshold of €1,000 is not a warning limit but a choice of route. If the amount to be corrected stays below it, the route is to include it in your next return. If it goes above it, the route is a separate suppletie. There is a penalty for not filing or not filing on time; sources differ on the amount, and that is why no amount is given here.
The direction does not matter. Reporting that you paid too little feels logical; reporting that you paid too much feels like something you have to ask for yourself. In both cases it is the same report, and in the second case you get money back.
Where is a suppletie in the law?
These legal sources come from the specialist dossiers that were reviewed on 31 August 2026. Mind the difference that becomes large in a dispute: a statutory article next to a value is where that value is found, not a justification for how it applies to your situation.
- Article 10a of the Dutch General State Taxes Act (AWR)imposes the obligation to report inaccuracies on your own initiative
- Article 15 of the Dutch VAT Implementing Decree 1968 (Uitvoeringsbesluit omzetbelasting 1968)works out that obligation for VAT: the look-back period of five calendar years, the threshold of €1,000, and since 1 January 2025 the deadline of eight weeks after the finding
The links go to the statutory text on wetten.overheid.nl, in the version that applied on 24 September 2026.
What does basestep do with a suppletie?
Preparing a suppletie is not in the platform and is not on the short-term plan either. What basestep does do is keep the derivation of every period, so you can show where the difference comes from at the moment you make the report yourself.
All calculations, explanations and signals in basestep are calculation support and instruction, not tax or legal advice. Amounts are estimates based on your own input; the Dutch tax authority (Belastingdienst) sets the assessment.
Where does it go wrong with a suppletie?
The two mistakes you run into most often in practice with this term, and what they cost you.
Including the error in the next quarter
A correction in the current period hides the error instead of fixing it, and with that also makes the new return incorrect.
Waiting until the year-end closing
The obligation arises at the finding, not at the closing. If you discover it in March, your eight-week deadline runs from March and not from December.
The clock starts at knowing, not at reporting
Because the eight weeks run from your finding, the moment you saw the difference counts. So record when you saw it, and act after that; postponing does not extend the deadline.
Further reading
Three places this term is tied to, inside this glossary and beyond.