How we make sure data stays current and checked
What you can see of the review date, the values with an effective date and the data that updates itself, and what we do when a source goes quiet.
A rate changes, a source stops, a text goes out of date. Here you can read what you can see of that and how we keep an eye on it. The bigger picture is in How we keep everything current.
A review date on every tool and every article
Every calculator and every article in which figures or rules can go out of date has a date on which we have to check it again. A month ahead we see that in our admin, and on the day itself we get a notification. The current values that tools share (see below) have such a date too.
That date does not move by itself: we only move it forward after a real check of sources, rates, calculation rules and texts. At the bottom of every tool and every article you see the day of that last check, on a tool as Last reviewed. It is not the day of the last publication. See What Last reviewed means.
Values with an effective date
Figures that appear in more than one text, such as a test rate or a legal maximum, are kept in one place, with a source and the date from which they apply. Every text that refers to them shows the value that applies today. If the value changes, it is right everywhere at the same time.
An example that is live now: the test rate (toetsrente) of the AFM (the Netherlands Authority for the Financial Markets) is currently 5% (since 1 October 2026). That number is not typed into this text, it is filled in at every visit.
| Value | Now | Since |
|---|---|---|
| Test rate for the maximum mortgage | 5% | 1 October 2026 |
| Cost limit of the National Mortgage Guarantee (NHG) | €470,000 | 1 January 2026 |
| Transfer tax (overdrachtsbelasting) on a home you live in yourself | 2% | 1 January 2026 |
| Maximum of the transition payment (transitievergoeding) | €102,000 | 1 January 2026 |
| Statutory minimum holiday pay | 8% | 1 January 2026 |
| Tax-free mileage allowance per km | €0.25 | 1 January 2026 |
If we already know that a rate changes on a certain date, we put the new value ready in advance with that date. It takes effect by itself, shortly after midnight on the day it applies. No release is needed and the old value stays until that day. The calculation rules of a tool we check separately, with the review date. For example, the maximum mortgage calculator (Dutch edition) uses rates that we check every year.
Data that updates itself
We fetch the open data of the lookup tools again at a fixed rhythm, as a full new copy. The rhythm of the source can differ from ours: we can fetch today while the source still has figures from last month.
| Source | How often we fetch |
|---|---|
| Prices from Statistics Netherlands (CBS): inflation, fuel, energy | every day; CBS updates daily pump prices weekly, the CPI and energy rates monthly and the quarterly prices about two months after the quarter ends |
| Vehicle register of the RDW (the Dutch vehicle authority) | every week; APK (periodic inspection), export and recalls per search |
| Weather measurements from the KNMI (Royal Netherlands Meteorological Institute) | every morning; the KNMI adds yesterday's measurements the next morning |
| Addresses (BAG), parking garages, charging points and filling stations | every month |
| Neighbourhood map, postcode figures and neighbourhood per address from CBS | per year, as soon as there is a new version; we check every week whether there is one |
| Core figures per municipality (gemeente) from CBS | every week; CBS updates the table irregularly |
More per source: CBS prices, the RDW data, KNMI weather data, Maps and addresses and CBS figures about neighbourhoods and municipalities.
With every load we check the copy before it goes live: are all fields still there, do the counts add up? If something is wrong, the previous load stays. So you never see a half load. Before we load a new year, we read the source's terms of use again.
The state of the data per tool
Below every lookup tool is the block About the data, and in articles about data there is Status today. There you see how far the series runs, when we last fetched it, how often we do that and who the publisher and the licence are. This is what it looks like for pump prices:
If a source goes quiet
If a source stops updating, or changes form, you see it on the page: the date by the data stays at the last state, and we do not say it is current. We get a notification ourselves. We then look at whether the source has stopped, has moved or has a different set-up, and adjust our tool or say that the data is no longer updated.
If our data service does not respond for a moment, a lookup tool says that searching is not possible right now. The calculators keep working.
Spotted a mistake?
Is something wrong, or out of date? Let us know via the contact page. We look at every report. An improvement to a tool is listed with the date under Changes.
How every result comes about and how we check the calculation rules, you can read in How our calculators work.
The Sumish editorial team
More guides
- How we workHow we keep everything currentWhich data updates itself, which rates we check by hand every year and what Last reviewed means on a tool.
- DataThe RDW vehicle dataWhere the Dutch Number Plate Check and the other car tools get their data, how often we update it and why we show nothing about owners.
- DataCBS prices: inflation, fuel and energyWhich Statistics Netherlands (CBS) series we use for inflation, pump prices and energy tariffs, how often they update and what provisional means.