Frequently asked questions about the PSO Performance Ladder

The PSO Performance Ladder (PSO-Prestatieladder) is a voluntary quality mark, valid for two years. You apply for it through PSO-Nederland, and a certification body audits it. Below are the questions we see most often, with a short answer and a link to the page where the topic is covered in full. The source for all answers is the PSO manual 2.6 from TNO , valid from 1 October 2026. PSO-Nederland updates the manual twice a year, on 1 April and 1 October. A new version applies to applications submitted after that date. Costs and steps are on applying for a PSO certificate and costs, and the calculation rules are on PSO levels and calculation.

On this page

• Is the PSO mandatory?
• How long is a PSO certificate valid?
• Who can apply for a PSO certificate?
• When does the certificate take effect?
• Do self-employed workers count?
• What is the difference between Aspirant status and Basic level?
• How much does it cost?
• What is the difference with PSO 30+?
• What does the calculation tool do?
• What is a certification body?
• How long does it take after the audit?
• What if the audit lowers my score?
• What if my certificate has already expired?
• Is the PSO related to the CO2 Performance Ladder?

Is the PSO mandatory?

No. The certificate is voluntary and is granted on application. A client can ask for social return in a tender and mention a PSO certificate as an option. For more, see is the PSO Performance Ladder mandatory?.

How long is a PSO certificate valid?

A maximum of two years. It ends automatically after two years. If you want to continue without a gap, submit a new final application in the month before the end date and have a new audit carried out. See renewing your PSO certificate.

Who can apply for a PSO certificate?

Organisations with at least two FTE in the reference year and, for a level, at least one year of registration with the Chamber of Commerce (KvK). See who the PSO Performance Ladder is for for the full list of checks.

When does the certificate take effect?

On the first day of the month after your final application in MijnPSO, not on the audit date. The certificate is therefore often backdated. It is only issued after the audit.

Do self-employed workers count?

Not for company size, when it concerns directly hired self-employed people without staff. These are left out of the calculation. Employees hired through temporary agencies, secondment or payroll companies do count. See company size in the PSO.

What is the difference between Aspirant status and Basic level?

Aspirant status is for organisations that do not yet meet the quantitative standard or the qualitative requirements, but want to reach the Basic level within two years. For this, you need a plan of action adopted at board level, and you must already have started on it. The Basic level requires a measurable result: you perform better than average for your size class (the best 50% of companies with at least one target group employee), and you meet the qualitative requirements. See the Aspirant plan of action and PSO requirements per level.

How much does it cost?

An annual fee to PSO-Nederland, which depends on the number of FTE in your final application, plus the audit costs from the certification body. The amounts are on the page applying for a PSO certificate and costs.

What is the difference with PSO 30+?

PSO 30+ is a separate recognition that is only available alongside level 3. It requires that at least 30% of your total workforce comes from the PSO target group. The manual links this recognition to the Public Procurement Act (Aanbestedingswet) of 1 July 2016. The act allows public clients to reserve contracts for companies with a high share of target group employees (article 2.82). For what this means in practice, see PSO in tenders.

What does the calculation tool do?

The calculation tool from PSO-Nederland works out your provisional level based on your data for the reference year. It is free to use, and you can also make several calculation tools to compare scenarios. Note that the calculation tool gives a provisional result. You only know your final level after the audit. See PSO levels and calculation for how the result is reached.

What is a certification body?

An independent party that carries out the audit and checks the data for PSO-Nederland. The auditor may adjust the score during the audit. You enter into an agreement with the certification body of your choice. The cost page explains which costs come on top.

How long does it take after the audit?

The auditor delivers the report within two working weeks. After that, PSO-Nederland decides. In practice, it often takes two to four weeks before the certificate is ready. This is a guideline, not a guarantee.

What if the audit lowers my score?

That can happen. The auditor works with a copy of your calculation tool and adjusts it wherever they cannot support something. This can lower the score, but it can also raise it. If evidence is missing, you have two weeks to supply it. See PSO audit: how does the audit work?.

What if my certificate has already expired?

A final application submitted within one year after the end date counts as a renewal for the qualitative requirements. If you apply one year or more after the end date, your application counts as a first application again. This is the most important point to plan for before the end date. See renewing your PSO certificate.

Is the PSO related to the CO2 Performance Ladder?

They are not the same. The CO2 Performance Ladder (CO2-Prestatieladder) is a separate scheme with its own standard and its own tests. For what the CO2 Performance Ladder means for tenders, see CO2 Performance Ladder and tender advantage. Do not compare the levels, because they measure different things.

Further reading

• PSO levels and calculation for the calculation rules.
• PSO in tenders for the social return side.