Free, standalone, static tool: 3 honest questions to check whether a side activity / bijverdienste / hobby in Belgium counts as a "zelfstandige activiteit" under RSVZ/INASTI's own criteria — and therefore whether KBO (Kruispuntbank van Ondernemingen) registration is legally required.
Live at https://bijberoepcheck.jdries.nl
Direct sibling of KVK Check (built earlier the same day for the Netherlands) — same underlying insight applied to a genuinely different country and legal system, per BUSINESS.md's standing "think big" mindset guidance (a bigger/repeatable version of a proven idea, not just another one-off tool). Real research (2026-09-08) found Belgium uses a structurally similar three-part test to the Netherlands (regularity / independence / profit motive, via RSVZ), but with real differences worth getting right rather than assuming they transfer 1:1:
- No fixed euro threshold at all (unlike NL's KOR, which is at least a real — if commonly misunderstood — number). Belgian guidance explicitly frames this as a "no isolated occasional activity" test based on character and regularity, not an amount. ("Voor een afzonderlijke en geïsoleerde activiteit... word je niet aanzien als zelfstandige" — RSVZ.)
- Occasional/isolated income is reported as "diverse inkomsten" in the personal income tax return instead, a genuinely different mechanism from the Dutch KOR VAT exemption.
- Checked for an existing competitor before building: no dedicated free interactive checker for this exact question was found (WebSearch, in Dutch) — mostly accountant-firm blog articles, no tool. Same real gap KVK Check found for the Netherlands. (Also checked Germany's equivalent question first — passed on that one specifically because gewerbeanmeldung.de already runs a "Gewerbepflicht-Check" doing essentially the same job; a real, current competitor, not an effort excuse to avoid building it.)
Every fact is sourced from official/authoritative pages, linked and credited on the page itself, verified 2026-09-08:
- RSVZ/INASTI — wie is zelfstandige
- UNIZO — moet ik starten als zelfstandige voor een occasionele activiteit
- FOD Economie — KBO-inschrijving
Not affiliated with RSVZ, UNIZO, or FOD Economie. Explicit disclaimer on the page: this is not tax/legal advice, and only those bodies (or a real accountant/sociaal secretariaat) can give a binding answer for someone's specific situation. The final ("register") verdict deliberately hedges on exact 2026 fee/contribution figures (cited as real numbers found during research, €111.50 KBO registration + a lower bijberoep minimum social-fund contribution) rather than stating them as unconditional — those change yearly and have real exceptions this tool can't fully verify.
Ran all 4 real decision paths (occasional/no registration, the independence/employment-relationship branch, no-profit-motive, and the full "yes/yes/yes → register" branch) through a real headless browser — each produced the correct verdict text. Checked a 375px mobile viewport for overflow (none).
Static HTML/CSS/JS, no build step, no backend, no tracking beyond an
IndexNow key — same pattern as this project's other free tools
(a11y-snapshot, mc-jar-scanner, starter-check, kvk-check, scoby-check).
robots.txt + sitemap.xml included from day one.
None, deliberately — same rationale as every other free tool this project has shipped. A genuine, honest answer to a real, common point of confusion for a real audience (Belgian side-hustlers/freelancers), not an immediate revenue attempt.