Certification process

Certification process

Certification process

Certification process

If your company is new to certification or you would like to know more, click on the link below to view NSI's approval process for both Gold and Silver NSI schemes:

NSI is an Assessing Body for the SIA’s Approved Contractor Scheme (ACS). Click on the link below to view the approval process for ACS:

Making an application

  • Contact applications team 
  • Receive quotation 
  • Submit application form and relevant documentation
  • NSI review application to determine eligibility 
  • Progress assessment audits

Granting approval 

After submitting an application for approval, NSI will conduct due diligence checks to determine if your organisation is eligible for approval. When these checks are successfully completed, we will arrange an initial assessment audit visit with you.

Dependant on the outcome of the due diligence checks and initial assessment we will do one of the following:

  • Issue the type of NSI approval you have applied for
  • Issue conditional or limited NSI approval
  • Reject your application and refuse to Approve your business

We will advise you in writing if we reject your application for any reason, or, if we intend to issue conditional or limited approval we will provide you with the reasons for this.

Following successful completion of the initial certification process, approval is granted for a period of three years (unless specified otherwise by the scheme), with the expiry date displayed on your certificate of approval.

Maintaining approval

To maintain your approval you must evidence your continuing compliance with scheme criteria and applicable standards through successful completion of our audit programme designed for you. Your NSI auditor will schedule your routine surveillance audits with you throughout the three-year audit programme. Approved Companies should proactively manage their audit programmes in conjunction with their auditor, to ensure surveillance audits are completed as required and to avoid the Approval being jeopardised.

Renewing approval

Every three years, in advance of your certificate expiring a Recertification audit visit will be scheduled.

Successful completion of the recertification process will result in your approval continuing for the next 3 years. You will not need to re-apply for approval.

Extending the scope of your approval

Extending or reducing your scope of Approval may mean a change to your audit programme.

To discuss an amendment to your scope of approval please contact the customer support team who will advise you accordingly: customersupport@nsi.org.uk  T: 01628 764888

Significant changes to your organisation 

Your audit programme will be designed for you taking into consideration the scale and complexity of your operations. Should there be any significant changes to your organisation during the course of your programme you will be required to inform us and we may make changes e.g. add additional audit visits into your programme. 

Suspending approval

Whilst rare, NSI reserves the right to suspend approval in a limited number of instances where NSI deems it to be appropriate. Such instances include:

  • Inability (and therefore failure) to comply with the NSI regulations, scheme criteria or applicable codes of practice for a given time period, due to a valid business reason and not due to intention to contravene the regulations, criteria, codes of practice or other applicable requirements.
  • Where a business holds approval, but for a period of time does not do any work under that approval, the business may request (or NSI may insist) that their certification be suspended for a period of time. At NSI’s discretion, the approval may be suspended for an agreed timeframe (typically no longer than 6 months).

Note: ‘Suspending approval’ means making the current NSI approval temporarily invalid for a fixed period of typically no more than 6 months, set by NSI.

Should you successfully meet the terms/requirements associated with the suspension within the prescribed timeframe, then NSI will remove the suspension.  Typically, completion of a successful special audit will be a pre-requisite to lifting a suspension.

Following removal of a suspension, the normal audit schedule will be resumed. There will be no change to the approval certificate issued by NSI, and issue and expiry dates will not change as a result of suspension of approval.

Withdrawing approval

NSI can at any time withdraw your NSI approval. The withdrawal of your NSI approval will be from any date we decide. You will be given notice in writing of the withdrawal. Reasons for withdrawal of Approval include;

  • Financial
  • Corporate
  • Performance
  • Changes to NSI Schemes


You can make an appeal against a Certification decision we have made regarding a particular clause within the NSI Regulations, Scheme Criteria or applicable standards.

You can also appeal against our decision where we have:

  • set special conditions for your NSI approval
  • granted you limited approval
  • changed the scope and sector of NSI approval your company has been granted or
  • suspended or withdrawn your approval (where appeal is permitted by the NSI regulations)

If you wish to appeal, you must give us written notice clearly setting out the reasons why you are appealing, within 28 days of the original decision. If you appeal against a decision, your appeal will not cause the decision to be delayed or postponed. The original decision stands until it is confirmed, changed or overturned as a result of a subsequent decision being made following your appeal.

On notice of appeal from the appellant, including an appeal deposit, the NSI Representative (typically the CEO) will confirm receipt and will issue the appellant with the NSI Appeals Guidance document. The NSI Representative will investigate and to try to resolve the matter within 28 days.

Should the appeal not be resolved within 28 days, the matter may be referred to an appointed Adjudicator, who may be a solicitor or barrister, independent of NSI and the appellant. An appeal hearing may be requested by the Adjudicator.

Following a final and binding decision by the Adjudicator, both NSI and the appellant will be informed of the outcome.

For full details please refer to the Regulations for Approved Companies.


Audit cancellation Policy

Cancellations of scheduled audits by our clients are few but, when they happen, directly impact on utilisation, efficiency and costs and at times impact re-certifications. Please view NSI's Audit Cancellation Policy.