In short
- Four of the scheme's dates are already spent. Publication was 14 January 2025 and certification against 4.0 opened on 14 July 2025.
- 14 January 2027 closes 3.1 audits and 3.1 tendering. It does not cancel a 3.1 certificate, which is why 14 January 2028 exists.
- The date that binds a certificate holder is its own first audit after 14 January 2027, not 14 January 2027 itself.
The next scheme deadline is 14 January 2027, and it closes two doors rather than opening one: no more audits against Handboek 3.1, and no more tenders using the 3.1 award criterion. Almost everything else on this timeline has already happened. Handboek 4.0 was published on 14 January 2025 and certifying bodies could audit against it from 14 July 2025. If you are reading that 4.0 arrives in 2027, you are reading a source that mixed up the start of the transition period with the end of it.
Which dates are spent, and which are still ahead?
| Date | Status | What it did or does | What has to be true |
|---|---|---|---|
| 10 June 2015 | Spent | Handboek 3.0 published | Nothing. Historical only |
| 22 June 2020 | Spent | Handboek 3.1 published. Five niveaus, four invalshoeken | Still a live text today |
| 14 January 2025 | Spent | Handboek 4.0 published for treden 1, 2 and 3 with the certificatieregeling. The 24 month overgangstermijn begins | You can read the new text. Nobody can yet be audited on it |
| 1 July 2025 | Spent | Overgangsregeling amended to version 1.1. Version 1.0 of 5 December 2024 withdrawn | Any transition rule you were told before this date needs rechecking |
| 14 July 2025 | Spent | Accredited certifying bodies may audit against treden 1, 2 and 3 | Certification against 4.0 is available |
| September 2025 | Spent | Handreiking Aanbesteden 4.0 published, carrying the renewed award criterion | Buyers have model tender texts. SKAO publishes no exact day, so do not quote one |
| 23 October 2025 | Spent | Harmonisatiebesluit 1: business travel targets and Well-to-Tank emissions at trede 1 | Binding on publication |
| 11 December 2025 | Spent | Harmonisatiebesluit 2: corrective action plan due within three months of a minor non-conformity | A finding is now a three month clock, not a next-audit item |
| 14 January 2026 | Spent | Earliest date SKAO advises a buyer to use the 4.0 award criterion | Earlier use was advised against outright |
| 1 June 2026 | Spent | Harmonisatiebesluit 3: a less recent base year is allowed where legal requirements demand it | Relaxes the three year base year cap in 4.0 |
| 14 January 2027 | Ahead | Last day a 3.1 audit may be performed. Buyers can no longer tender with version 3.1 | Your migration decision is made, and booked with your certifying body |
| 14 January 2028 | Ahead | Last day a valid 3.1 certificate can exist, 36 months after 4.0 was published | Nothing you can extend. It is a consequence, not a choice |
| 2050 | Ahead | The horizon written into trede 3: zero emissions in scope 1, 2 and 3 and beyond, at the latest | Applies to trede 3 certificate holders only |
Why do 2025 and 2027 keep swapping places?
Because the two dates share a day and a month. The overgangstermijn runs from 14 January 2025 to 14 January 2027, exactly 24 months. A source that has seen "14 januari" and "2027" in the same paragraph reports a handbook landing in 2027, and every page that copies it inherits the mistake.
The cost of the error is not academic. It makes the Dutch market look two years less advanced than it is, and it tells a reader that there is time to do nothing. There is not: two of the three biggest buyers on this instrument have already set their own switch dates, and one of them has already switched.
What actually has to be true by 14 January 2027?
Less than the date implies, and something more specific.
The obligation is to have moved to Handboek 4.0 by your first audit after 14 January 2027, not by 14 January 2027 itself. If your annual audit falls in November, your practical deadline is November 2027, not January. If it falls in February, you have weeks rather than months. Work backwards from your own audit date, because the scheme does.
Two things determine how much work that migration is. If you hold a valid 3.1 certificate and take a 4.0 audit for trede 1, you may continue your existing 3.1 audit cycle, including any audit-time reduction you had already earned. A 4.0 audit for trede 2 or trede 3 is always an initial audit, even for an organisation sitting at niveau 5 today. The second case is a first certification with a first certification's calendar, whatever the label on your current certificate says.
Is 14 January 2028 a deadline at all?
Not one you act on. It is the arithmetic consequence of the previous row.
A 3.1 audit performed shortly before 14 January 2027 produces a certificate that stays valid until the next annual audit. Push that forward twelve months and you land on 14 January 2028, which is 36 months after 4.0 was published. That is the last day on which a valid 3.1 certificate can exist anywhere in the scheme.
It matters because of what it rules out. A 3.1 certificate is not void on 14 January 2027, and anyone telling you the old handbook becomes worthless that day is wrong for up to a year. It also matters for what it does not do: SKAO's equivalence advice runs one way only. Where a buyer tenders on the 3.1 criterion, a 4.0 certificate can be accepted as proof. Where the criterion is 4.0, a 3.1 certificate is never acceptable proof, however valid it still is.
Which deadlines on this list are not SKAO's?
The commercially important ones. Each contracting authority sets its own switch date inside the window SKAO advises, and they have not agreed with one another.
Rijkswaterstaat moved to Handboek 4.0 on 1 July 2026, for procurements published on TenderNed after that date, and weights the treden at 2, 4 and 6 percent. Procurements it published before that date stay under 3.1. ProRail intends to use 4.0 from 1 January 2027 in newly published TenderNed procurements where the Ladder is an award criterion, with a provisional weighting of 4, 7 and 10 percent, and warns that some tenders can carry a different weighting. Note that ProRail's date sits two weeks before the scheme deadline, not on it.
The lesson for a bid calendar: the date that governs a given procurement is the date that procurement was published, and the arrangement that governs it is in its own documents.
What sits in your own calendar rather than the scheme's?
Three entries, and none of them is 14 January.
Your first audit after 14 January 2027. The real migration deadline. Book the certifying body conversation well before it, especially if you are aiming at trede 2 or 3, where the audit is an initial one.
Your base year. Under Handboek 4.0 the base year at an initial audit may be no more than three years before the year of that audit. If you are planning an initial audit for a 2028 calendar, a base year of 2024 will be outside the window by the time you get there. Harmonisatiebesluit 3 of 1 June 2026 relaxes this only where a legal requirement demands an older base year.
Three months from any minor non-conformity. Since Harmonisatiebesluit 2 that is a hard clock rather than something you fold into next year's cycle.
Where does the data work actually sit on this timeline?
Behind every one of these dates is an annual audited inventory that somebody has to be able to trace. The Hedgehog platform names the CO2-Prestatieladder among its reporting outputs, holds entity management across locations and sites with roles for data owners, auditors and managers, and reports 5,000+ users on its platform page. The limitation to weigh against your own timeline: a mid-market reviewer on G2 in June 2026 noted there are few integrations with other software today, so if your plan for hitting an audit date depends on an automated feed from an ERP, check that before you build the schedule around it.
If the migration decision itself is where you are stuck rather than the tooling, that is carbon footprint consulting territory. If you are also inside CSRD scope, scope the two together rather than twice, since SKAO built 4.0 to align with it: CSRD consulting. And for the scheme from a standing start, read our introduction to the CO2-Prestatieladder for SMEs.
Sources: SKAO Overgangsregeling 3.1-4.0 v1.1 of 1 July 2025, Handboek 3.1, SKAO migration and documenten pages, Harmonisatiebesluiten 1 to 3, Handreiking Aanbesteden 4.0, ProRail supplier page, Rijkswaterstaat news of 18 March 2026, Hedgehog platform, Hedgehog on G2. Verified 28 August 2026.
Facts on this page were last verified on 2026-08-28.
