What is the difference between certification and accreditation?

Certification means your organisation has been independently assessed against a defined standard and issued a formal certificate. Accreditation is the formal recognition that a certification body itself is competent to carry out assessments — typically granted by a national body like UKAS. NAS operates as an independent certification body aligned with ISO/IEC 17021 principles, assessing organisations and issuing formal certificates based on documented evidence.

Do I need certification to work on construction sites in the UK?

There is no legal requirement to hold a specific certification. However, most principal contractors, housing associations, councils, and NHS trusts require evidence of compliance before awarding work. NAS certification provides that evidence — independently assessed and publicly verifiable, with real assessor review of your actual documents.

How much does NAS certification cost?

NAS Basic is £349/year, NAS Bronze is £749/year, NAS Silver is £950/year, and NAS Gold is £1,150/year. Pricing is flat — never scaled by headcount or turnover. Loyalty discounts apply from year 2 (5% rising to 20% by year 5).

How long does NAS certification take?

Most NAS assessments complete within 3-5 working days of evidence submission. The full process from application to certificate typically takes 1-3 weeks.

What is ISO 17021 and why does it matter?

ISO/IEC 17021 is the international standard governing bodies that certify management systems. It requires independent assessors, separation of assessment and decision-making, and evidence-based decisions. NAS operates its certification scheme in alignment with these principles.

How long is NAS certification valid?

NAS certification is valid for one year and is renewed annually. The annual renewal cycle ensures your compliance is kept current. Loyalty discounts apply from year 2.

Approved Contractor Register UK | NAS Certified Business Register

Quick Answer

What is an approved contractor register?

An approved contractor register is a publicly accessible list of contractors that have been independently assessed and verified as meeting a defined compliance standard. Unlike a membership list — which simply records businesses that have paid to join — an approved contractor register only includes businesses that have passed an assessment. The NAS Certified Business Register lists contractors whose compliance evidence has been reviewed by an independent NAS assessor.

How the NAS Certified Business Register Works

The NAS Certified Business Register is the public-facing list of businesses that hold a current NAS certificate. To appear on the register, a business must:

Submit compliance documents for assessment
Pass the independent NAS assessor review
Be issued a NAS certificate at one of the four tiers (Basic, Bronze, Silver, Gold)
Renew annually to maintain their listing

Each listing shows the business name, trade category, NAS tier, certification status and certificate number. Buyers can verify a certificate directly using the NAS certificate verification tool.

Approved Contractor Register vs Membership List

Many schemes described as "approved contractor lists" are in practice membership schemes — any business that pays the joining fee is listed, with no independent review of compliance evidence. This provides limited assurance to buyers.

The NAS register operates differently. A business only appears on the register after passing an independent evidence review. If a renewal is not submitted or evidence does not meet the standard, the certificate lapses and the listing is removed.

How to Get Listed on the NAS Register

Apply online and select your NAS tier (Basic, Bronze, Silver or Gold)
Submit your compliance documents via the NAS platform
An independent NAS assessor reviews your evidence
If the evidence meets the standard, a NAS certificate is issued
Your business is listed on the public NAS Certified Business Register

Who Uses the NAS Register

The register is used by housing associations, local authorities, NHS trusts, main contractors, facilities management companies and commercial property managers to verify contractor compliance and find certified businesses for their supply chains.

Approved Contractor Register UK Certified Business Register

What is an approved contractor register?

How the NAS Certified Business Register Works

Approved Contractor Register vs Membership List

How to Get Listed on the NAS Register

Who Uses the NAS Register

Frequently Asked Questions