Choosing an SIA approved contractor
How to choose an SIA approved contractor and why you should.
Check our register of approved contractors
You can find out if a company is approved by searching our register of approved contractors.
Why you should choose an SIA approved contractor
When you hire a private security company you have a choice between one of our approved contractors or a company we have not approved.
On this page we list some of the reasons why you should choose an SIA approved contractor.
We have also produced a guide that covers a few other points to consider when choosing a security supplier. Download our guide .
Quality assured by the industry regulator
Our Approved Contractor Scheme (ACS) provides a recognised hallmark of quality within the private security industry.
We assess our approved contractors against 78 different areas of their business. These cover topics as diverse as staff training, financial management and the company’s health and safety policies.
When you choose an approved contractor you can be sure that the business you are working with has passed a thorough quality assurance check.
A commitment to quality
Our Approved Contractor Scheme (ACS) is a voluntary scheme. Any company that is part of the scheme has chosen to be.
Our ACS is a progressive quality standard. That means we continually raise the standard that companies must meet in order to be approved.
Quality assurance from top to bottom
Sub-contracting is a common practice in the private security industry. Approved contractors may only sub-contract to other approved contractors unless we have given them special permission to do otherwise. As a result, you can be confident that the quality of service you expect will be maintained.
A focus on you, the customer
Our ACS standard encourages approved contractors to tailor their services to your needs.
Compare approved contractors
Most approved contractors score their performance against the ACS standard every year. These scores are then verified by independent assessors.
Businesses approved through one of our accredited passport schemes are not required to submit scores.
Can the score show how good a company is?
The score can give an indication of the overall quality of an approved contractor, but it does not tell the whole story.
This is because:
- the company may get a low score overall but score well in a particular aspect of their business operations
- the company may get a high score overall but score poorly in a particular aspect of their business operations
We recommend that you also look at factors such as the contractor’s reputation in the marketplace or the quality of its tender response.
You should also consider reading the contractor’s assessment report. We can give this to you if the approved contractor gives us permission to do so.
How does the scoring system work?
The contractor is scored against 78 achievement indicators. These cover topics as diverse as staff training, financial management and the company’s health and safety policies.
The pass mark for each indicator is the required achievement level, so a positive score (like +1) shows that the company is doing more than it needs to.
If we find that a company is falling below the standard we will work with them to improve that area of their operations. If they do not, we will withdraw their approval.
The maximum overall score that can a company can achieve is 145.
What scores do companies tend to achieve?
We show the average initial annual assessment scores below, broken down by size of organisation. We measure the size of an organisation by the number of licensable staff it has.
| Number of licensable staff | Average score |
| Up to 10 | 41 |
| 11 to 25 | 62 |
| 26 to 250 | 82 |
| Over 250 | 125 |
These figures are drawn from the period 1 October 2025 to 30 September 2026.
We have used the median as the average. This is calculated by arranging the scores in order from the smallest to the largest and then selecting the middle score.
The diagram below shows the percentage of approved contractors achieving certain scores. The dotted white line represents the pass mark. Each segment of the pyramid above that represents 25% of the maximum score.
Scores for the top 5% of initial annual assessments
For the reporting period mentioned above, the scores for the ‘top 5%’ (highest scoring) approved contractors were: 142, 142, 142, 140, 140, 140, 139, 138, 138, 138, 138, 137, 136, 136, 135, 135, 134, 134, 134, 133, 131, 131, 131, 131, 131, 130, 130, 130, 130.