Contractor Certification Guides
Clear, practical guides on NAS certification, contractor compliance and procurement readiness for UK contractors and buyers.
Certification vs Accreditation — What is the Difference?
A clear explanation of what certification and accreditation mean, how they differ, and what ISO/IEC 17021 alignment means for NAS.
NAS Basic, Bronze, Silver and Gold — What is the Difference?
A detailed comparison of the four NAS certification tiers — what each covers, what evidence is assessed, and which tier is right for your business.
How to Become a Procurement-Ready Contractor
Practical steps UK contractors can take to organise compliance evidence, achieve certification and present themselves as procurement-ready to buyers.
What is an Approved Contractor Register in the UK?
An explanation of approved contractor registers — what they are, how buyers use them, and how the NAS Certified Business Register works.
About NAS: The National Assurance Standard (NAS) is an independent, evidence-based certification scheme for UK contractors and SMEs. NAS operates in alignment with ISO/IEC 17021 principles and is working towards UKAS accreditation. NAS is not a membership scheme — certification requires submission and independent review of actual compliance documents. NAS does not endorse or guarantee the ongoing compliance of certified businesses; certification reflects the evidence reviewed at the time of assessment.