In short
- The next date is the A2 weegset for projects published on TenderNed from 2027. Rijkswaterstaat names no specific day.
- The move to Handboek 4.0 is not upcoming. It happened on 1 July 2026, at 2, 4 and 6 percent.
- What decides which rules govern a bid is the publication date of the procurement, not the date you submit.
The next Rijkswaterstaat date is the European A2 weegset, which applies to projects published on TenderNed from 2027 and takes the MKI calculation from 11 to 19 environmental impact categories. Rijkswaterstaat expects MKI values to become on average roughly twice as high and says A1 and A2 results cannot be compared one to one. The date most sources still treat as ahead, the switch to Handboek 4.0 of the CO2-Prestatieladder, is behind: it happened on 1 July 2026, at 2, 4 and 6 percent. What has to be true is that you know which rules govern each live bid.
Which dates exist, and which are spent?
| Date | Status | What it does | What has to be true |
|---|---|---|---|
| 18 March 2026 | Spent | Rijkswaterstaat announces the move to Handboek 4.0 from 1 July 2026 and the 2, 4 and 6 percent weighting | The market had notice. RWS set the date in consultation with SKAO and other public clients |
| 21 May 2026 | Spent | Rijkswaterstaat publishes the MKI protocol 5.0 changes, the planned A2 weegset move and the release of DuboCalc 8.1 | Your LCA team has read protocol 5.0 |
| 1 July 2026 | Spent | Handboek 4.0 enters the aanbestedingsleidraad, for procurements published on TenderNed after this date only. Trede 1 is a 2 percent fictitious reduction of the bid sum, trede 2 is 4 percent, trede 3 is 6 percent | You know which trede you can realistically declare and deliver |
| 1 July 2026 | Spent | MKI protocol 5.0 takes effect and is issued with the tender documents of new projects | Your MKI calculations follow protocol 5.0, not an earlier one |
| Projects published from 2027 | Ahead | The European A2 weegset replaces A1, moving the LCA from 11 to 19 impact categories. RWS names no specific day | Your calculator is A2 capable and your team knows A1 numbers do not carry across |
Which date actually governs a given bid?
The date the procurement was published on TenderNed. Not the closing date, not the award date, and not the date you started writing.
Rijkswaterstaat applies Handboek 4.0 only to procurements published after 1 July 2026. Anything published before that stays under Handboek 3.1, scored on the five niveaus, and a 4.0 certificate offered under the scheme transition arrangement is still mapped back onto those niveaus. The A2 weegset works the same way, applying to projects published from 2027, with running projects keeping the data versions fixed in their contracts.
The consequence for a bid team is that two live tenders on the same desk can be governed by different handbooks and different weegsets at the same moment. Reading the publication date first is not administrative diligence, it is the thing that tells you which rulebook you are answering.
What has already happened that people still call upcoming?
The Handboek 4.0 switch, and it is the single most common error about Rijkswaterstaat.
A great deal of writing places the change in 2027, because that is the year the CO2-Prestatieladder's own transition period ends and because ProRail's switch falls then. Rijkswaterstaat moved six months earlier, on 1 July 2026, and its staffel is different from anyone else's. If a source tells you Rijkswaterstaat is preparing to adopt 4.0, it is describing a decision that was announced in March 2026 and executed in July 2026.
MKI protocol 5.0 is in the same position. It has been in force since 1 July 2026 and is sent out with new tender documents, so an MKI value built against an earlier protocol is not the value the tender is asking for.
Why does the A2 weegset deserve its own line in the calendar?
Because it changes the numbers without changing the design.
The European LCA norm for construction products moved from 11 to 19 environmental impact categories, adding water scarcity, particulate matter, ionising radiation and land use and soil quality among others. Rijkswaterstaat expects the resulting MKI values to become on average roughly twice as high, and says A1 and A2 results are not comparable one to one.
Note precisely what that does and does not mean. It does not mean a design becomes twice as damaging. It means the calculation counts more things, so the number is larger. Two practical consequences follow. Internal benchmarks and target MKI values carried over from A1 projects will read as failures against A2 numbers unless they are restated. And any comparison across a portfolio has to be made within one weegset, not across the boundary.
Rijkswaterstaat says only that the A2 set applies to projects published on TenderNed from 2027. It does not name a day, and neither should anyone else. DuboCalc 8.1, rebuilt and A2 capable, has been released to support the change.
Which deadlines on this list are not Rijkswaterstaat's?
The scheme's own dates, and they run on a different clock.
The CO2-Prestatieladder's transition period ends on 14 January 2027, after which audits against Handboek 3.1 can no longer be performed and contracting authorities can no longer tender with the 3.1 criterion. A 3.1 certificate from a late audit can stay valid until 14 January 2028. Those dates constrain your certifying body and your own audit calendar; they are not Rijkswaterstaat dates and they do not change what governs a procurement already published.
What has to be in your own calendar?
Three entries, and only one of them is a Rijkswaterstaat date.
Your certificate proof deadline, per contract. Proof of the declared trede is due after the project finishes, or one year after award on longer projects. That is a per-contract clock that starts at award, so it is your contract register rather than the scheme calendar that holds it. Rijkswaterstaat noted when it announced the switch that there would be time in 2027 to execute a herstelplan if a first audit fell short, which is a repair window rather than an extension.
Your first audit after 14 January 2027. The scheme requires the move to 4.0 at that audit, not on that date. If your annual audit falls in November, your real deadline is November.
Your A2 restatement. Before you bid on anything published in 2027, restate whatever internal MKI benchmarks you use, or you will read a normal A2 number as a bad result.
Where does the work behind these dates sit?
On two different desks, and only one of them is a carbon accounting system.
The trede rests on an audited organisational inventory. The Hedgehog platform names the CO2-Prestatieladder among its reporting outputs and reports 5,000+ users on its platform page. The limitation worth checking against a dated bid plan: a mid-market reviewer on G2 in June 2026 said they would like more integrations with other software in the future, so if hitting an audit date depends on an automated feed from a project or ERP system, verify that before you build the schedule around it.
The MKI half is LCA work in a validated calculator against the Rijkswaterstaat protocol, and carbon accounting software does not produce it. If the organisational inventory itself is the gap, that is carbon footprint consulting work, and our introduction to the CO2-Prestatieladder for SMEs covers the scheme from a standing start.
Sources: Rijkswaterstaat news of 18 March 2026 and 21 May 2026, Rijkswaterstaat duurzaam inkopen and DuboCalc pages, Protocol Berekenen en aantonen MKI waarde, SKAO Overgangsregeling 3.1-4.0 v1.1, Hedgehog platform, Hedgehog on G2. Verified 18 September 2026.
Facts on this page were last verified on 2026-09-18.
