Box 3: Netherlands' Wealth Tax Ruled Unconstitutional
Box 3 was ruled unconstitutional in 2021. Then the fix was illegal too. The government tried to raise it anyway. Here's the full story.
On Christmas Eve 2021, Dutch investors got an unusual present. The Hoge Raad (Dutch Supreme Court) ruled that Box 3 — the country's wealth tax on savings and investments — was unconstitutional. It had been taxing people on fictional returns they never earned, in violation of European Convention on Human Rights protections on property and non-discrimination.
That ruling, known as the Kerstarrest, made national headlines. Most Dutch investors have at least heard of it.
What fewer people know: the government's fix was also ruled illegal. Then, while billions in refunds remained outstanding, the government proposed raising the tax. Parliament blocked it. And the actual structural reform keeps getting delayed, now scheduled for 2028, two years later than originally promised.
This is the full story of box 3 belasting Netherlands: one of the most prolonged tax policy failures in recent Dutch history.
What Is Box 3?
The Dutch income tax system divides income into three categories. Box 1 covers income from work and your primary residence. Box 2 covers substantial business interests. Box 3 covers returns from savings, investments, and other capital assets: stocks, bonds, ETFs, a second property, crypto, and most financial products above a tax-free threshold.
The threshold in 2026 is €59,357 per person (€118,714 for fiscal partners).
Until very recently, Box 3 did not tax what you actually earned. The Belastingdienst (Dutch Tax Authority) applied a deemed, fictional return based on your asset values, and you paid tax on that assumed figure regardless of your real performance. For years, the assumed return on "other assets" (essentially anything that wasn't a savings account) sat at roughly 5.88%. You paid 36% tax on that assumed return.
If you held €200,000 in index funds and the market had a flat year, the Belastingdienst assumed you earned roughly €11,760 and billed you accordingly.
Retail investors using tools like Folia to track their actual portfolio returns would have noticed the disconnect immediately: their real return was visible in the dashboard; what they were taxed on was an entirely different number.
The Kerstarrest: What Actually Happened on December 24, 2021
The Hoge Raad issued ruling ECLI:NL:HR:2021:1963 on December 24, 2021. The court found that Box 3, as structured, violated Article 1 of Protocol No. 1 to the European Convention on Human Rights (right to property) and Article 14 ECHR (prohibition of discrimination).
The central finding was not subtle. Taxing people on income they did not earn, with no mechanism to report actual returns, is a breach of fundamental rights. The court offered immediate relief by limiting taxation to actually realized returns for affected taxpayers.
The implications were enormous. Every taxpayer who had paid Box 3 taxes from 2017 onwards had potential grounds for a refund. The Belastingdienst had collected billions in tax revenue under a system a court just declared unlawful.
Dutch Degiro users in particular had reason to pay attention. If your portfolio of ETFs and dividend stocks earned 2-3% in a low-rate year, you had been taxed as if you earned 5.88% or more. For context on the kind of costs Dutch investors already absorb in the brokerage space, see our breakdown of Degiro fees in 2026.
The Government's Attempted Fix
The Dutch government responded with two successive frameworks. The Herstelwet (Restoration Act) covered tax years 2017-2022 and offered compensation to taxpayers who had objected. The Overbruggingswet (Bridging Act) extended a counter-evidence system through 2026, allowing taxpayers to report actual returns instead of the fictional rates.
On paper, this looked like a solution. In practice, it fell short in several ways.
The frameworks used fictional rates as the default. Claiming your actual returns required proactive action, documentation, and in many cases professional help. For the mass objection window covering 2017-2020, a significant number of eligible taxpayers missed the deadline entirely. The Belastingdienst's communication around this period did not cover its authors in glory.
More critically, the new frameworks did not fully resolve what the Supreme Court had identified. The assumed returns on stocks, bonds, and real estate under the Overbruggingswet still diverged from actual market conditions in weak years, and the calculation methods for "other assets" remained discriminatory in the court's view.
June 2024: The Fix Got Ruled Illegal Too
On June 6, 2024, the Hoge Raad issued a second landmark ruling. The court found that both the Herstelwet and the Overbruggingswet still violated ECHR protections.
The ruling stated plainly that "a significant difference in tax treatment between successful and less successful investors continues to exist, without sufficient justification." The counter-evidence mechanism was not sufficient. The calculation of returns on stocks, bonds, and real estate remained fundamentally discriminatory.
The court's requirement was clear: Box 3 assessments must be reduced so that tax is levied only on the actual return realized in a given year. Actual return means direct yield (dividends, interest, rental income) plus changes in asset value, including unrealized gains and losses.
A follow-up clarification came on December 20, 2024, addressing specific calculation questions around immovable property and WOZ valuations.
Two Supreme Court rulings in three years, both finding the system in breach of European human rights law. The financial exposure by this point: €2.8 billion already allocated for initial compensation, plus an additional €9.8 billion identified for 2017-2026 overpayments, roughly €12.6 billion in total, plus hundreds of millions in interest costs accumulating on outstanding refunds.
Prinsjesdag 2025: The Part That Should Make You Angry
At Prinsjesdag in September 2025, the Dutch government presented its Belastingplan 2026. Among the proposals: raising the fictional return on "other assets" from 5.88% to 7.78%. The tax-free allowance would also drop from €57,684 to €52,048 per person.
Consider the timing. The Supreme Court had ruled in June 2024 that the existing system still violated European human rights law. The government owed over €12 billion in refunds. The actual replacement system was not yet operational. And the government's proposal was to extract more revenue from the same illegal system in the meantime.
In November 2025, the Tweede Kamer rejected the increases. The final 2026 rate for other assets was set at 6%, a modest increase from 5.88% but well below the proposed 7.78%. The tax-free allowance was actually raised to €59,357. The Eerste Kamer confirmed the amended plan on December 16, 2025.
We will not dress this up as a nuanced policy disagreement. The Dutch government has had four years to fix a system its own courts declared illegal. The response included band-aid legislation, a second court defeat, and then a proposal to squeeze additional revenue from the same broken system while billions in refunds sat unresolved. That Parliament blocked it is the correct outcome; the proposal should not have been made.
For Dutch investors trying to plan around tax implications, this level of policy instability carries real costs. Our guide to investment strategies for Dutch investors covers some of the structural approaches worth considering when the tax environment keeps shifting.
What's Coming: The 2028 Reform and Why It's Controversial
On February 12, 2026, the Tweede Kamer approved the Wet werkelijk rendement box 3 with 93 votes in favor. The bill awaits ratification by the Eerste Kamer before its planned implementation on January 1, 2028.
This reform was originally scheduled for January 1, 2026. Then 2027. Now 2028.
What the new system does: Starting in 2028, Box 3 will tax actual returns at a flat rate of 36%. Actual returns include direct yield (dividends, interest, rental income) and changes in asset value, including unrealized capital gains.
That last point deserves specific attention.
If you hold €60,000 in ETFs and they rise 15% in 2028, you will owe 36% tax on €9,000 in unrealized gains. The position has not been sold. No cash has changed hands. But the tax bill is real.
This is a significant shift. Every prior version of Box 3 taxed assumed income on wealth. The new system taxes mark-to-market returns, including gains that exist only on paper. For long-term investors who hold positions for years or decades, this creates a structural change in how portfolio growth translates into tax obligations.
Crypto holders face similar exposure. A token that doubles in value in a given year generates a taxable event even if the wallet is untouched.
Some investors see the reform as a fairer approach than the fictional-rate system: at least you pay on what you actually earn. Others, particularly those with illiquid assets or concentrated long-term positions, are more skeptical. The cash-flow implications of annual unrealized gain taxation are not trivial.
2030: One More Change on the Horizon
Here is where it gets even more complicated. The 2028 system is not the final destination.
The current coalition agreement includes a plan to transition Box 3 to a full vermogenswinstbelasting (capital gains tax) by 2030. Under that system, you would only pay tax on gains when you actually sell an asset, with no annual taxation on unrealized appreciation. A stock that rises 20% in a year would generate no tax bill until you sell.
That would be a meaningful improvement for long-term investors and would align the Netherlands more closely with how most other European countries treat capital gains. The problem is that it is a stated intention in a coalition document, not enacted law. And given that Box 3 has now missed three consecutive implementation deadlines, there is no shortage of reasons to treat the 2030 timeline with caution.
In February 2026, there were also reports that the Minister of Finance indicated even the 2028 plan might require significant revision given parliamentary criticism over taxing paper gains and the removal of loss carry-back provisions. Whether the 2028 system survives intact, gets amended before implementation, or gets replaced entirely by an earlier move to a capital gains model remains unclear at the time of writing.
What is clear: Dutch investors should expect the Box 3 rules to keep changing. Planning around a specific system that is still not law is a risky approach. Build flexibility into your tax planning.
The regulatory pattern here is not isolated to the Netherlands. European governments are increasingly tightening investment-related regulation and taxation. For a broader view of how the EU regulatory environment is changing, see our piece on PFOF regulation in Europe.
What Dutch Investors Should Do Now
There are concrete actions worth taking in 2026 before the 2028 system arrives.
Claim counter-evidence refunds if eligible. The Wet tegenbewijsregeling box 3, in force since July 1, 2025, allows you to document actual returns for 2017-2024 and claim refunds where your real returns were lower than the fictional rates. This is not automatic. You need to file, document, and ideally work with a tax advisor. If you held mainly savings in any year when interest rates were near zero, the refund potential is likely meaningful.
Understand the 2026 Box 3 rates as they stand. For 2026, the assumed return on other assets is 6% and the tax rate is 36%. If your actual investment returns exceeded 6% in 2026, the fictional rate may actually work in your favor this year. Do the calculation for your specific portfolio before opting into counter-evidence for 2026.
Model the 2028 impact on your portfolio. Unrealized gain taxation will affect long-term investors the most. If you hold positions that have significantly appreciated, it is worth modeling what annual tax obligations look like under the new system. That is not an argument to sell, but it is an argument to plan.
Build clean records of your portfolio's actual performance. The new system requires accurate annual tracking of dividends received, realized gains, and unrealized value changes across every asset class. Spreadsheets become increasingly insufficient for this. A portfolio tracker that logs actual returns, dividends, and cost basis automatically gives you clean data when the Belastingdienst needs it. Folia tracks Dutch investors' portfolios including Degiro accounts, with dividend history and performance data in one place, exactly the kind of record you'll want to have ready in 2028.
The Bigger Picture
Box 3 is not just a Dutch tax problem. It is a case study in what happens when a government designs a tax system around administrative convenience and revenue predictability, then resists dismantling it cleanly when courts say it must go.
The Dutch government knew Box 3 was legally vulnerable long before 2021. When the court finally ruled, the response was a series of patches that satisfied neither the Hoge Raad nor taxpayers. Each patch bought time while the liability grew. By the time the actual reform passed the Tweede Kamer in February 2026, the total refund exposure had reached approximately €12.6 billion.
The replacement system, for all its fairness in taxing actual returns, introduces its own serious complications. Taxing unrealized gains annually is a policy that most European tax regimes avoid for good reason. The Netherlands will be navigating that experiment starting in 2028.
Dutch investors deserve clarity and consistency. What they have had, since Christmas Eve 2021, is four years of legal limbo, failed fixes, a brazen attempt to raise an illegal tax, and a replacement bill that raises new questions even as it resolves old ones.
Understand the system you are operating in, claim what you are owed, and track your actual returns with enough precision that you are ready for what 2028 brings.
This article is for informational purposes only and does not constitute tax or financial advice. Consult a qualified Dutch tax advisor for guidance specific to your personal situation.
Frequently asked questions
What is Box 3 in the Netherlands?
Box 3 is the Dutch wealth tax system that taxes income from savings, investments, and other capital assets. Until 2028, it uses deemed (fictional) return rates rather than taxing actual returns. The tax-free allowance in 2026 is €59,357 per person.
Why was Box 3 ruled unconstitutional?
In December 2021, the Dutch Supreme Court ruled that Box 3 violated the European Convention on Human Rights because it taxed investors on fictional returns they never earned, especially during years of near-zero interest rates.
Can I get a refund for Box 3 overpayments?
Yes. The counter-evidence system (Wet tegenbewijsregeling box 3), in force since July 1, 2025, allows you to demonstrate your actual returns were lower than the fictional rates and claim a refund for years 2017-2024 onwards.
When does the new Box 3 system start?
The new actual-return system (Wet werkelijk rendement box 3) is planned for January 1, 2028. It was approved by the Tweede Kamer in February 2026 and still needs Senate ratification.
Will I be taxed on unrealized gains under the new Box 3?
Yes. Under the 2028 system, unrealized capital gains on stocks, bonds, crypto, and real estate will be taxed at 36%, even if you haven't sold the asset. This is a significant change from the current system.
What is the 2030 Box 3 plan?
The Dutch coalition agreement includes a plan to introduce a full vermogenswinstbelasting (capital gains tax) by 2030, taxing gains only when assets are sold rather than annually. It is a stated intention, not enacted law, and its timeline is uncertain given Box 3 has already missed three implementation deadlines.
