Stichting Normering Arbeid (SNA) is the Dutch independent foundation that owns and operates the NEN 4400-1 and NEN 4400-2 certification schemes for staffing, payrolling, and sub-contracting agencies. It accredits the inspection bodies that audit agencies and publishes the online register hirers use to verify supplier status.
SNA itself does not perform audits. It sets the scheme rules, commissions biannual inspections through accredited auditors, and removes non-compliant agencies from the register. The register is the practical reference point the Belastingdienst, hirers, and procurement teams use when assessing inlenersaansprakelijkheid risk.
For a hirer, checking the SNA register before engaging an agency is a baseline due-diligence step. Combined with payments to a G-account, SNA certification is the recognised route to limit chain liability for wage tax and VAT under the Wet ketenaansprakelijkheid.