NAS-STD-001 v1.0NAS Contractor
Certification Standard
Evidence-Based Contractor Assurance Framework
The NAS Certification Standard sets out the evidential requirements, assessment methodology, governance arrangements and standards alignment for each certification tier. Intended for contractors, buyers, procurement teams and framework providers.
Document Control
Important: NAS is an independent contractor certification framework operated by NAS — National Assurance Standard. It is not government approved, HSE approved, or UKAS accredited. Alignment with recognised standards does not imply approval or endorsement.
Section 1
Introduction to NAS
What the framework is, who it is for, and how it operates.
What is NAS?
NAS is an independent contractor certification framework providing an independent, evidence-based route for UK contractors, SMEs and trade businesses to demonstrate legal compliance, operational competence and supply chain readiness.
Verifiable Status
Every certificate has a number and an expiry date that anyone can check on the public register. Certificates that lapse, or are suspended or withdrawn, stop showing as current.
Who It's For
UK contractors and SMEs, buyers and procurement teams, framework providers, main contractors, housing associations, local authorities, NHS trusts, and any supply chain participant requiring independently verified contractor compliance data.
Section 2
Scope of Certification
What all NAS members receive, and how tiers are differentiated.
All Members Receive
Regardless of tier, all NAS members access:
- Secure applicant portal for questionnaires and evidence upload
- Reminders before the certificate and key documents expire
- NAS Public Certification Register listing
- NAS digital certificate
- Access to assessor feedback and corrective action reports
Tier Differentiation
The distinction between tiers is not portal access. It is:
- The areas assessed — each tier adds to the one below
- The depth of evidence reviewed
- Procurement suitability and framework compatibility
Higher tiers carry greater evidentiary weight for procurement purposes and supply chain risk assurance.
Section 3
NAS Certification Tiers
Detailed requirements, assessment scope, and procurement suitability for each tier.
Tiers are cumulative: each application includes every requirement from the tiers below it. The areas listed are the ones in the approved question bank (NAS-2026-02); some apply only where relevant to your work.
Overview
Health and safety certification covering the SSIP core criteria.
Intended For
Sole traders and small businesses that need health and safety evidence.
Basic covers the SSIP core criteria. NAS is not currently an SSIP member scheme, so Basic does not give SSIP mutual recognition.
What is assessed
Overview
Everything in Basic plus core legal and employment compliance.
Intended For
Small and medium contractors with employees.
Everything in Basic, plus
Overview
Everything in Bronze plus environmental, quality, governance and employment management systems.
Intended For
Established businesses working for larger clients and frameworks.
Everything in Bronze, plus
Overview
Everything in Silver plus 13 procurement modules.
Intended For
Businesses bidding for public sector, framework and main contractor work.
Gold procurement modules are CAS-aligned but do not constitute CAS certification.
Everything in Silver, plus 13 procurement modules
Section 4
Assessment Methodology
How applications are processed, reviewed, decided and monitored.
Evidence Submission
Applicant completes the online form and uploads required evidence. Answers are saved per question with a full audit trail.
AI-Assisted Pre-Review
For Bronze, Silver and Gold, an AI-assisted review checks evidence completeness and generates an initial summary for the assessor.
Independent Assessor Review
A trained NAS assessor independently reviews all submitted evidence. The assessor has no commercial relationship with the applicant.
Corrective Actions / RFI
Where evidence is incomplete, a Corrective Action Request or Request for Information is issued with a defined response window.
Certification Decision
A separate decision manager reviews the assessor recommendation and makes the final certification decision. Sales has no involvement.
Certificate Issue & Register Update
If approved, a NAS certificate is issued, the public register is updated, and the business can be found and verified by buyers.
Ongoing Monitoring
Certificate status is actively monitored on a continuous basis. Annual reassessment is required to maintain certification.
Suspension & Withdrawal
Certification may be suspended or withdrawn where evidence of non-compliance is identified. A formal process applies with right of response.
Section 5
Governance & Impartiality
How NAS ensures integrity, independence and fairness across the certification process.
Impartiality Controls
- Assessors are appointed based on competence, qualifications, and sector knowledge
- Assessors declare conflicts of interest prior to each assessment; conflicts result in reassignment
- Sales, marketing and commercial functions are operationally separated from assessment and decision-making
- All decisions, evidence reviews and status changes are logged in a tamper-evident audit trail
- Certificate suspension and withdrawal follow a documented process with applicant notification and right of response
Complaints & Appeals
- A formal complaints procedure is in place; investigated by a person independent of the original assessment
- An appeals process is available; reviewed by a senior decision maker not involved in the original decision
- Evidence submitted is stored securely and handled in accordance with UK GDPR
- Impartiality controls are documented and subject to periodic review by the NAS governance committee
- Complaints and appeals outcomes are recorded and inform continuous improvement of the scheme
Section 6
Certification Status & Verification
How buyers can check that a NAS certificate is genuine and current.
Each certificate is valid for one year from the date it is issued and is renewed with a fresh evidence review. Its status — current, expired, suspended or withdrawn — is shown on the public register, so a buyer always sees where it stands.
Public Certification Register
Every NAS certified business is listed on the public register with their tier, status and certificate expiry. Fully searchable by buyers and procurement teams.
Certificate Verification
Any buyer or procurement team can verify a contractor's NAS certificate online at any time using the certificate number or company name.
Digital Certificate
NAS certified businesses receive a digital certificate showing tier, issue date, expiry and scope. Suitable for use in tender submissions.
Expiry Monitoring
Automated alerts are triggered for insurance and certificate renewal. NAS monitors expiry proactively and updates the public register accordingly.
Procurement Evidence Pack
Certified businesses can share their NAS certificate and tier summary with buyers and procurement teams as part of pre-qualification submissions.
Section 7
Standards & Legislative Alignment
How NAS relates to recognised standards. Alignment does not imply government approval, accreditation or endorsement.
Alignment with the standards listed below does not imply government approval, UKAS accreditation, or endorsement by any government body, scheme provider or regulatory authority. NAS is an independent certification scheme.
| Standard / Legislation | NAS Tier Alignment |
|---|---|
| PAS 91:2013+A1:2017 | Silver, Gold |
| CDM 2015 | All tiers (construction work) |
| MHSWR 1999 | All tiers |
| Procurement Act 2023 | Bronze, Silver, Gold |
| UK GDPR / DPA 2018 | Bronze+ |
| Modern Slavery Act 2015 | Bronze+ |
| Equality Act 2010 | Bronze+ |
| Bribery Act 2010 | Gold |
| Companies Act 2006 | Bronze+ |
| Building Safety Act 2022 | Gold |
| Common Assessment Standard | Gold |
Appendix
Frequently Asked Questions
Section 8
Version Control
| Version | Issue Date | Review Date | Status | Author | Summary |
|---|---|---|---|---|---|
| 1.0 | 15 May 2026 | 15 May 2027 | Active | NAS | Initial issue — full NAS Certification Standard |