Frequently asked questions about the CO2 Performance Ladder
Below are the questions asked most often about the CO2 Performance Ladder. The questions range from basic information to practical choices. Click through to the detailed pages for more information. The scheme is managed by SKAO ; the official documentation is on co2-prestatieladder.nl .
Is the CO2 Performance Ladder mandatory?
No, the CO2 Performance Ladder is not a legal requirement. No law says you must obtain the ladder. But for companies that bid on public tenders in construction, infrastructure, ICT or advisory work, the ladder is in practice often required or strongly rewarded as an award criterion. For what that means per tender, read is the CO2 Performance Ladder mandatory?.
Public authorities such as Rijkswaterstaat, ProRail and municipalities use the ladder to give sustainable parties an advantage. If you want to bid on those contracts, the ladder is therefore in practice necessary.
What is the difference between levels and steps?
The CO2 Performance Ladder has two versions that exist side by side in 2026. Handbook 3.1 uses five levels (1 to 5). Handbook 4.0, published on 14 January 2025, replaces those five levels with three steps. The two classifications are not interchangeable: level 3 is not the same as step 3.
As a rough mapping, step 1 broadly equals level 1 to 3, but it is stricter. Step 2 corresponds to level 4 and 5. Step 3 goes further than any level in 3.1. See the detailed explanation on the page levels and steps.
Which version applies in 2026?
In June 2026 both versions are valid. You can be certified on handbook 3.1 or on handbook 4.0. The SKAO transition arrangement sets the following timeline:
- From 14 July 2025: 4.0 audits possible
- From 1 July 2026: Rijkswaterstaat applies 4.0 in new GWW (civil engineering) tenders
- Until 14 January 2027: 3.1 audits still possible
- Until January 2028: existing 3.1 certificates valid
Always check the tender document to see which version is required.
What does the CO2 Performance Ladder cost?
The costs consist of three parts. First, the annual contribution to SKAO. This ranges from €65 (sole trader) to €6,000 (turnover of €500 million or more), based on annual turnover. Official rates are on co2-prestatieladder.nl/nl/tarieven .
Then there are the audit costs at an independent certification body. These are indicatively €3,000 to €4,000 for the first certification, and €1,500 to €2,500 per annual surveillance audit. Finally, there are your own hours and possibly a consultant.
The full overview is on costs and timeline.
How does the tender advantage work?
The tender advantage is a notional discount on your bid price in tenders. Your actual amount does not change, but the contracting authority assesses your bid as a lower amount. The higher your level or step, the bigger the discount.
Example: you bid €30 million and the level gives 4% advantage. The contracting authority calculates your bid price as €28.8 million. That is €1.2 million of advantage compared with a competitor without a certificate who bids the same amount.
Read more on tender advantage.
Do I need a certificate to submit a bid?
No. When you submit a bid, you state your ambition level. You do not need to hold the certificate yet. SKAO advises demonstrating the certificate within about one year after award.
Do check the sanctions, though, if you do not reach the level you stated. Check the contract conditions carefully before you state a level you cannot be sure to reach.
How long does certification take?
For the basic level (level 3 or step 1), plan for three to six months. Preparation takes most of the time: calculating your footprint, drawing up a reduction plan and setting up communication. The actual audit is quick. Higher levels take longer, because the chain must be included.
The full step-by-step plan shows what you do at each step and how long it takes.
Who may audit the ladder?
Only certification bodies (CIs) accredited by the Raad voor Accreditatie (RvA, Dutch Accreditation Council) under scheme S571 may do so. In Belgium this is Belac. Well-known CIs include Kiwa, DNV, DEKRA, Bureau Veritas, SGS, Normec and Aboma.
Check whether the CI you choose already holds an accreditation for handbook 4.0. Not all CIs have one yet. More information is on the page certification bodies.
Is ISO 14001 the same as the CO2 Performance Ladder?
No. ISO 14001 is a management system standard for all environmental aspects. The ladder focuses specifically on CO2 reduction. ISO 14001 checks whether your system works. The ladder checks whether your emissions actually fall, and links that to tender advantage.
You can combine them, but ISO 14001 gives no automatic advantage or shortcut in the ladder certification. Read more on CO2 Performance Ladder vs ISO 14001.
Does ISO 50001 or ISO 14001 help with the ladder?
Both standards overlap with the ladder, but neither gives an automatic exemption or shortcut. ISO 50001 requires an energy review that resembles the emissions inventory of the ladder, which saves preparation work. ISO 14001 gives you the habit of setting and monitoring targets, which the ladder also requires.
However, you still need your own CO2 footprint, reduction targets, publications and proof of participation that meet the specific ladder requirements.
How long is a certificate valid?
The certificate is valid for three years. Each year an auditor visits for a surveillance audit. After three years a recertification follows: a complete new assessment. See the audit process for the full cycle.
Is the ladder suitable for a sole trader or small business?
Yes. Sole traders and small businesses can obtain the ladder. The annual contribution starts at €65 for a sole trader. The scope for step 1 or level 3 is limited to your own organisation. With the SKAO practical guide, you can do the process yourself, without a consultant.
Read more on CO2 Performance Ladder for SMEs.