For years, the Dutch Box 3 tax system has been one of the most controversial aspects of the Netherlands' tax code. The government taxed wealth not on what you actually earned from your savings and investments, but on a fictional assumed return (forfaitair rendement). After the landmark Supreme Court ruling (Kerstarrest) in December 2021, which declared this system a violation of property rights, the government has been scrambling to build a replacement. In 2026, we are in the middle of that transition, and every Dutch investor and saver needs to understand what is happening.
This guide explains the current transitional system, what the final actual-return model will look like, and how you can prepare your finances accordingly.
The Problem with the Old Box 3 System
Under the old system, the Belastingdienst divided your Box 3 assets into two categories: savings and investments. It then applied a fixed deemed return to each category — for example, 1.44% on savings and 6.04% on investments in 2025. You paid a flat 36% tax on the total deemed return, regardless of what you actually earned.
This created obvious injustices. If your bank account earned 0.5% interest but the government deemed it earned 1.44%, you were paying tax on €9,400 of phantom income for every €1 million in savings. Meanwhile, someone whose investments actually earned 15% paid the same rate as if they had earned 6.04%. The system over-taxed cautious savers and under-taxed successful investors.
The Hoge Raad ruled this violated Article 1 of Protocol No. 1 to the European Convention on Human Rights. The government was ordered to provide redress to affected taxpayers, and a new system based on actual returns became legally necessary.
The Current Transitional System (2023-2026)
Since the full actual-return system is not ready yet, the government implemented a transitional regime that uses improved deemed-return calculations based on three asset categories:
- Bank deposits (banktegoeden): The deemed return is based on the actual average savings interest rate published by DNB (De Nederlandsche Bank). For 2026, this is approximately 1.6%.
- Other investments (overige bezittingen): This category includes shares, bonds, funds, crypto, and second properties. The deemed return is still calculated using a long-term average, approximately 6.04% for 2026.
- Debts (schulden): A fixed deduction rate is applied to reduce your taxable base if you have debts in Box 3.
The tax-free threshold (heffingsvrij vermogen) for 2026 is approximately €57,000 per person (€114,000 for fiscal partners). Only wealth above this threshold is taxed. Use our Box 3 tax calculator to see exactly how much you owe.
The Upcoming Actual-Return System (Wet Werkelijk Rendement)
The government is targeting 2027 for the introduction of the full actual-return system. Under this new law, you will be taxed on what you genuinely earned from your assets in Box 3 — actual dividends received, actual interest earned, actual rental income, and actual capital gains realised.
Key features of the planned system include:
- Annual reporting of all actual income from Box 3 assets
- Unrealised capital gains on listed securities may be taxed annually (mark-to-market)
- Real estate (second homes) would be taxed on actual rental income or a deemed return based on WOZ value
- Losses can potentially be offset against gains, creating a more balanced system
- The 36% tax rate is expected to remain, applied to actual rather than deemed income
This is a fundamental shift. Under the current system, a bad year in the stock market still triggers a tax bill. Under the actual-return system, losses would reduce or eliminate your tax obligation for that year.
What This Means for Different Investor Profiles
Conservative savers: If you hold most of your wealth in bank accounts, the transitional system is already more favourable than the pre-2023 rules. The actual-return system will be even better, as you will only pay tax on genuine interest received. With savings rates hovering around 2% to 3%, your tax bill should be modest.
Equity investors: The impact depends on your returns. In good years, you may pay more tax under the actual-return system than under the current deemed-return model. In bad years, you will pay less. Over time, the volatility of your tax bill increases, but the system is fundamentally fairer.
Property investors: If you own a second property (tweede woning) or buy-to-let property, the shift to actual returns could significantly increase your tax burden if your rental yields are high. Currently, properties in Box 3 are valued at their WOZ value with a relatively favourable deemed return. Under actual returns, your genuine rental income will be the taxable base.
Run different scenarios with our rental income calculator and Box 3 tax calculator to understand your exposure under both systems.
How to Prepare Your Portfolio
While you cannot control when the government implements the new system, you can take steps to prepare:
- Keep detailed records of all investment income, including dividends, interest, and rental receipts
- Understand which of your assets sit in Box 3 versus Box 2 (if you have a BV, some restructuring may be beneficial — use our ZZP vs BV calculator)
- Consider the tax implications before making large property purchases — our transfer tax calculator can help
- Review your debt structure, as debts in Box 3 reduce your taxable wealth
- Consult a belastingadviseur (tax adviser) for personalised planning
Key Takeaways
- The old Box 3 deemed-return system was ruled illegal by the Supreme Court.
- A transitional system with improved asset-category calculations is in effect for 2026.
- The full actual-return system (Wet Werkelijk Rendement) is planned for 2027.
- Savers benefit from the reform; property investors may face higher bills.
- Keep meticulous records of all investment income to prepare for the transition.
Calculate your current Box 3 liability with our Box 3 tax calculator and explore the full range of Dutch tax calculators to understand your complete financial picture.