Why Your Model ROZ Rent Clause Can Rise Faster Than Your Salary

I've had tenants send me their lease after the first indexation letter arrives, confused and a little panicked. "My rent went up 6%, my salary went up 2.5%, is this even legal?" Usually the answer is: yes, and it's written right there in Article 4 of the Model ROZ template they signed eight months earlier.

Model ROZ (from the Raad voor Onroerende Zaken) is the standard lease template used across the Dutch rental market, residential and commercial. Its rent review clause links the annual increase to the CPI published by CBS, and in a lot of contracts — especially commercial ones and older residential ones — it adds a fixed surcharge on top, commonly 3% or more.

That surcharge is the part nobody reads carefully. It's one line. It looks harmless. It isn't.

Take a fairly typical example: €1,500 a month, CPI running at 3.4%, plus a 3% surcharge. That's a 6.4% annual increase, compounding.

After five years: €1,500 × (1.064)^5 ≈ €2,046 a month. That's a 36% increase in five years — on a lease where nothing about the apartment changed.

Now compare that to wage growth. In the 2026 numbers I've seen, average CLA wage growth sits around 2.7%, while CPI itself was 3.4% and the statutory private-sector cap was set at 4.4% (CPI + 1%). Even without a surcharge, a tenant on the statutory maximum sees their rent grow 4.4% a year while their paycheck grows 2.7%. That gap of 1.7 percentage points doesn't sound dramatic until you compound it for five or ten years — then it becomes the difference between rent eating 30% of your income and rent eating over 40%.

The Wet Betaalbare Huur (Affordable Rent Act) introduced real caps depending on your housing segment: social housing up to 143 WWS points is capped at 4.1% from July 2026, the mid-segment (144–186 points) at 6.1% from January 2026, and free-sector housing at 187+ points at 4.4% from January 2026, tied to the lower of CPI or CLA wage growth plus 1%.

That's genuinely useful if you know your WWS points and know where your unit falls. But here's the catch: the Dutch Supreme Court has ruled that a 'CPI + 3%' surcharge clause isn't automatically unfair for residential leases if it's clearly disclosed — the ruling limited enforceability in some cases, but plenty of existing contracts, especially older ones and commercial leases, still carry these surcharges and get applied at or near the statutory ceiling every year regardless.

Amsterdam District Court has even referred questions to the CJEU about whether these clauses are compatible with EU consumer protection rules — transparency, balance, whether the formula only ever moves upward. Until that's resolved, landlords keep applying the clause as written, and tenants keep paying it unless they push back.

The Model ROZ clause is structurally one-sided. It triggers increases when CPI rises. It almost never triggers a decrease when CPI is flat or negative. So even in a year where inflation cools off, your rent doesn't cool off with it — it just increases a little less.

And in cities like Amsterdam, Utrecht, Rotterdam, Den Haag, or even Groningen and Eindhoven where vacancy rates are near zero, tenants rarely challenge these clauses. Nobody wants to be the person disputing an indexation letter with a landlord who has three other applicants lined up. I've seen this play out constantly through House Hunter's alerts — the moment a decent listing appears, forty people apply within hours. That desperation is exactly why landlords can write in an aggressive clause and expect it to go unchallenged.

Don't wait for the increase letter. Before you sign anything, find the indexation clause and identify three things:

First, what index does it reference — CBS consumer price index, and which specific series? Second, is there a fixed surcharge on top, and what percentage? Third, does the clause cap the increase at the statutory maximum for your housing segment, or does it just say 'CPI plus X%' with no reference to the 2026 caps at all?

If you can find those three numbers, you can model your actual multi-year cost. Take your current rent, apply the formula for five years, and compare that number to a realistic salary growth line — starter salaries and CLA increases in most Dutch sectors sit well under 4% a year. If the gap between the two lines is more than a percentage point or two, you're not looking at a rent that tracks inflation modestly. You're looking at a rent that structurally outpaces your income, year after year, by design.

If your unit falls under social or mid-segment WWS points, check those numbers against the Huurcommissie's rules — you may have grounds to challenge an increase above the legal cap. Huurteams in most cities will do this calculation with you for free.