The CO₂ Performance Ladder explained: a guide for organisations outside the Netherlands

What is the CO₂ Performance Ladder?

The Ladder is a carbon management system. You map your energy flows, build a footprint in line with ISO 14064-1 and the GHG Protocol, set reduction targets, implement measures, and have all of it audited by an accredited certification body. What you get is a CO₂-bewust certificaat, a CO₂ awareness certificate, valid for three years with an annual surveillance audit.

The Ladder is also a procurement instrument. Public buyers attach a financial advantage to your certificate level when they evaluate your bid. The certificate exists because contracting authorities do something with it at award.

It is owned and managed by SKAO, the Dutch foundation for climate friendly procurement and business, which reports around 8,000 certified organisations, 75 percent of them SMEs, and over 300 public procuring authorities using it. SKAO cites research by CE Delft and Utrecht University showing that certified organisations reduce emissions roughly twice as fast as uncertified ones. The scheme has been running since 2009.

The vocabulary stays Dutch even in English-language tenders, so it is worth learning the six words that matter.

How does tender advantage actually work?

The mechanism is called fictieve korting, a notional discount. The contracting authority names the Ladder as an award criterion (gunningscriterium). You bid at a declared CO₂ ambition level. During evaluation your price is reduced by a percentage, a fixed amount or a number of points. If you win, you are paid the full price you quoted.

A worked example. A bid of 30 million euro with a 4 percent advantage is evaluated as 28.8 million euro, which beats an uncertified bid of 29 million euro. The winner still invoices 30 million euro. The discount exists only inside the scoring.

SKAO publishes an illustrative model for version 4.0 and leaves the choice to the buyer: "Welk percentage, bedrag of puntenaantal u als gunningsvoordeel kiest, bepaalt u zelf", which means the percentage, amount or number of points is the authority's own decision (SKAO on tendering with version 4.0).

Real percentages run lower. Rijkswaterstaat, the Dutch national infrastructure agency, applies 2 percent for Trede 1, 4 percent for Trede 2 and a maximum of 6 percent for Trede 3 on new procurements published from 1 July 2026 (Infrasite). ProRail, the rail infrastructure manager, has used the Ladder since 1 December 2010 and applies an advantage that rises with ambition level. Check the live tender document for its exact figures, because published sources disagree.

Four rules from the SKAO FAQ that foreign bidders miss most often:

• A certificate may not be used as a suitability or selection requirement (geschiktheidseis). SKAO calls that a breach of equal treatment, proportionality and non-discrimination. You cannot be excluded from bidding for not holding one.
• You do not need to be certified to bid. You declare an ambition level and then demonstrate it within one year of award, with either a certificate or a projectverklaring.
• In a consortium, the member with the lowest level caps the level the whole consortium can claim.
• If you fail to reach the level you declared, a contractual sanction follows. SKAO advises setting it higher than the advantage granted, for example the difference multiplied by 1.5.

The full mechanics, including use below EU procurement thresholds, are in tender advantage with the CO₂ Performance Ladder.

How many levels does the Ladder have?

The Ladder has three steps, called treden. Handbook 4.0 was published on 14 January 2025 and replaced the five levels of version 3.1. SKAO's own wording is "Vervanging van vijf niveaus door drie treden met hoger ambitieniveau", five levels replaced by three steps with a higher ambition level (SKAO, What is the Ladder). Old levels 1 and 2 were deleted. Old level 3 became the entry point.

Almost every English-language page describing this scheme still says five levels. A supplier guide or an AI-generated summary that talks about five levels is describing the outgoing version.

In February 2025 SKAO wrote that a Trede 4 for absolute frontrunners is in development, that it will not be introduced before 2026 at the earliest, and that on introduction it will initially not be included as an award criterion (SKAO on the three steps). As of August 2026 we have found no SKAO publication releasing it. Treat any description of what Trede 4 contains as speculation.

You will meet both vocabularies for at least another year, since the last possible audit against version 3.1 is 14 January 2027. The rough translation is that Trede 1 corresponds to old Niveau 3, and Trede 2 and 3 to old Niveau 5, which leaves old Niveau 4 without a clean successor. SKAO's own pages disagree on the detail: the FAQ, the tendering blog and the transition arrangement each phrase the mapping differently. All three are laid side by side in why there are now three steps instead of five levels, which is also where the vocabulary question belongs. A sustainability lead put it this way: "We have an auditor who is really allergic when you use step instead of level."

Which countries use the Ladder in 2026?

SKAO's official position: "The CO2 Performance Ladder is being introduced in France, Germany, Ireland, Portugal and the UK, alongside its established presence in the Netherlands and Belgium" (SKAO, the Ladder in your country).

Belgium is the second real market and behaves differently from the Netherlands, with its own certification bodies and its own procurement rules. That is covered in the CO₂ Performance Ladder in Belgium.

On 25 March 2025 SKAO and the European Commission launched the CO₂ Performance Ladder Europe Community of Practice at the Big Buyers Working Together annual event in Helsinki, with seven countries taking part. It runs on the European Commission's Public Buyers Community platform, which describes the Ladder as "an easy-to-implement, tested and internationally recognised best practice Green Public Procurement instrument". International rollout is funded by the IKEA Foundation, with IISD, Utrecht University, CO₂logic and ICLEI as partners.

Outside the Netherlands and Belgium this is market development. We have not been able to confirm a single contracting authority outside those two countries actually granting tender advantage today. If a consultant tells you the Ladder already earns you points in France, Germany, Portugal, Ireland or the UK, ask to see the tender document.

How far along is Ireland?

Ireland is furthest along. The pilot ran from 2023 to 2025, led by the Irish Green Building Council with SKAO. Three companies achieved company-wide certification, including a Colas joint venture that reached Level 3. SKAO reports that Transport Infrastructure Ireland has embedded the Ladder into three new four-year frameworks, and reports "an 84.5% reduction in Scope 1 and 2 emissions and 311 tonnes of CO₂ equivalents saved" (SKAO, Ireland).

The same SKAO page also states: "Transport Infrastructure Ireland (TII) was the first procuring authority to apply the Ladder as an award criterion." We quote that rather than repeat it as our own finding. Read literally it sits oddly against Dutch practice, where ProRail has used the Ladder in procurement since 2010, and we have found no published Irish tender document showing an advantage actually granted and quantified. What is checkable is the framework agreements.

In February 2026 the Construction Industry Federation published a guidance note for Irish contractors. Its most useful line is operational: "TII is encouraging contractors to adopt Handbook 4.0 directly during the transition period ... rather than certifying under the outgoing 3.1 version." That advice travels. A 4.0 certificate is valid in a tender asking for 3.1, and a 3.1 certificate is not valid in a tender asking for 4.0, because version 4.0 goes further. The reuse and rewrite detail is in migrating from 3.1 to 4.0.

What is happening in the United Kingdom?

The UK has been in pilot since May 2024, with Action Sustainability as SKAO's delivery partner, and Transport for London took part as a public buyer. The published retrospective on that implementation contains one lesson that applies to every new market: "start small but dive in. Pilot it with a few high-carbon procurements to refine the process before scaling up" (Action Sustainability).

Whether Transport for London granted tender advantage, and how much, does not appear in the published material. We have not been able to establish it, so we leave it out.

Can an organisation outside the Netherlands be certified?

Yes. The scheme conforms to NEN-EN-ISO/IEC 17021-1 and is accredited by the Raad voor Accreditatie in the Netherlands and BELAC in Belgium. There are fifteen accredited or authorised certification bodies, three of them Belgian: BCCA, COPRO and Vinçotte. Separately, a few parties offer the Ladder internationally, among them TÜV NORD UK and Bureau Veritas Benelux. TÜV SÜD is qualified but does not appear on that list of fifteen. Ask any body you approach to confirm in writing that it can issue an accredited certificate for your country.

You have two routes, and they are not equivalent.

The single-use rule is SKAO's own: "Een projectverklaring is slechts eenmalig geldig, specifiek voor het project waarover het wordt afgegeven door een Certificerende Instelling" (SKAO FAQ).

You cannot build the footprint with emission factors of your own choosing. The Ladder prescribes a country-specific list, which the GHG Protocol does not.

Two further departures from what international reporters are used to. Carbon offsetting falls outside the Ladder's measurement scope, so credits cannot move you up. And green electricity is defined more strictly than under generic market-based accounting: generated from sun, wind, water or biomass, in the same country where it is consumed.

What does the Ladder cost?

SKAO's annual contribution runs from € 65 for a sole proprietorship to € 6,000 at turnover above € 500 million. The sentence that matters most to groups is on the costs page: "A company, including its subsidiaries, will never pay more than €6,000 per year in total contributions." For a group with thirty subsidiaries that figure acts as a ceiling.

SKAO also estimates € 3,000 to € 4,000 for initial certification, € 1,500 to € 2,500 per year afterwards, and 100 to 200 working hours of implementation effort. Consultancies publish higher all-in ranges. The full breakdown, and which figures come from SKAO rather than from consultants, is in what the CO₂ Performance Ladder costs.

Where does it get hard?

Rarely in the carbon maths. It gets hard at the organisational boundary, especially for groups operating across several countries. A sustainability lead described the root cause this way: "The reason that this is so complicated is because you have two overlapping systems." There is a statutory structure of legal entities for the annual accounts, and an operational structure of business units for running the work. They do not line up, and the Ladder asks you to report on a boundary that cuts across both. That problem is worked out in group boundaries on the CO₂ Performance Ladder.

The second hard part is the audit. Auditor time is a fixed budget, roughly three days once a year, with little room to iterate beforehand, and the recurring findings are collected in what auditors reject.

How does the Ladder relate to CSRD, ISO 14001 and CDP?

SKAO is explicit and positive on CSRD: "By meeting the requirements of the CO₂ Performance Ladder version 4.0, an organisation covers part of the ESRS set, specifically ESRS E1 on climate change." And: "the footprint produced by the organisation in accordance with the CO₂ Performance Ladder requirements can be used directly in the CSRD report, since the same scope classification is used, all greenhouse gases (not just CO₂) are included" (SKAO on CSRD and 4.0). The climate transition plan required at Trede 2 is the deliberate bridge to the transition plan disclosure in ESRS E1.

The limit is just as clear. The Ladder covers climate. Social topics and governance are left entirely uncovered, so an organisation in scope of CSRD has one standard addressed and the rest still open. One practical trap: the entity list inside your Ladder certificate is often not the entity list inside your CSRD report. The crosswalk is in the CO₂ Performance Ladder and CSRD.

The 4.0 handbooks follow the Harmonized Structure used by ISO standards, which eases integration with ISO 9001 and ISO 14001. Joining CDP on the basis of the Ladder is not possible, because in CDP's terms the Ladder is not an internationally accepted method.

How Palau handles this

Palau is a Belgian sustainability reporting platform that supports the CO₂ Performance Ladder alongside CSRD, VSME and EcoVadis, with a customer base in construction and infrastructure. The Organisational structure module consolidates across legal entities, which is the work sitting behind the boundary problem above. Vault manages evidence and documents against the reporting they belong to, so nobody has to hunt for them during the audit. There is more on our CO₂ Performance Ladder solution page.

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