Box 3 Tax Calculator 2026

Box 3 Explained: How the Netherlands Taxes Your Wealth

The Dutch income tax system is divided into three distinct compartments, called boxes. Box 1 covers your employment income, pension, and primary residence. Box 2 covers substantial shareholdings in companies (5% or more). Box 3 -- the focus of this calculator -- covers all other savings and investments. For expats and international workers accumulating wealth in the Netherlands, Box 3 is often the most surprising and sometimes frustrating part of the Dutch tax system.

What makes Box 3 unusual by international standards is that it does not tax your actual investment gains. You could lose €20,000 on the stock market in a given year and still owe Box 3 tax, because the tax is levied on a deemed return -- a fictional rate of return that the government assumes you are earning. Conversely, if your investments gain 20%, you only pay tax on the much lower deemed return. This system creates predictability for the government's tax revenue but can feel deeply unfair to taxpayers in loss years.

The Three-Category System: Deep Dive

Since the Box 3 overhaul in 2023, your assets are divided into three categories, each with its own deemed return percentage. These percentages are updated annually by the Dutch Tax Authority based on actual market data from the previous year. Understanding each category and what it includes is essential for accurate tax planning.

Category 1: Savings -- Deemed Return of 0.36%

The savings category captures all liquid cash positions: money in current (checking) accounts, savings accounts, term deposits, and even physical cash. The deemed return of approximately 0.36% in 2026 reflects the very low interest environment that has characterized Dutch banking in recent years. This rate is based on the average interest rate actually earned on Dutch savings accounts in the preceding year, as reported by DNB (De Nederlandsche Bank).

For expats, a crucial question arises: what about savings in foreign banks? If you maintain a savings account in your home country -- say, a high-yield dollar account in the US earning 4.5% or a pound sterling account in the UK earning 3% -- that money is still classified as "savings" for Box 3 purposes. You benefit from the low 0.36% deemed return even though your actual return may be many times higher. This is one of the few situations where the deemed return system works strongly in the taxpayer's favor.

Important caveat: cash held within a brokerage or investment account may be reclassified as an investment by the tax authority. To ensure your cash is treated as savings, keep it in dedicated bank accounts that are clearly separate from your investment platforms.

Category 2: Investments -- Deemed Return of 5.88%

The investment category is the broadest and includes everything that is not savings or a debt. The deemed return of approximately 5.88% is substantially higher than the savings rate, reflecting the long-term average return on a diversified investment portfolio. This rate is derived from a statutory formula based on 15-year average returns on equities, bonds, and real estate.

Assets in this category include:

• Listed securities: stocks, bonds, ETFs, mutual funds on any exchange worldwide
• Cryptocurrency: all digital assets (Bitcoin, Ethereum, stablecoins, NFTs with monetary value)
• Real estate: any property that is not your primary residence -- second homes, rental properties, land, commercial property, foreign real estate
• Receivables: money others owe you, including loans to family or friends
• Other valuable assets: precious metals (gold, silver held as investment), options, futures, and structured products

The 5.88% deemed return has significant implications. Consider an expat who owns a rental apartment in their home country worth €200,000. Even if the rental yield after costs is only 2% and the property does not appreciate in value, the Dutch government assumes a 5.88% return -- €11,760 of fictional income on which you owe 36% tax, or €4,234. That is an effective wealth tax of 2.12% on the property value, paid on top of any local property taxes in the country where the property is located.

Category 3: Debts -- Deduction at 2.47%

Qualifying debts reduce your Box 3 tax base, providing some relief. The deemed return on debts is approximately 2.47%, which means for every €10,000 of eligible debt, your deemed return is reduced by €247. At the 36% tax rate, this translates to a tax saving of approximately €89 per €10,000 of debt.

There is a debt threshold (schuldendrempel) that you must exceed before debts count. In 2026, this threshold is approximately €3,700 per person or €7,400 for fiscal partners. Only the amount of debt above this threshold is included in the Box 3 calculation. Common qualifying debts include personal loans, margin loans on investment accounts, loans from family members, and study loans from DUO (the Dutch student finance authority).

What does not qualify: your mortgage on your primary Dutch home is a Box 1 item and does not affect Box 3 at all. However, a mortgage on an investment property or second home does qualify as a Box 3 debt -- creating a partial offset against the high investment deemed return on that property.

Calculating the Weighted Average Deemed Return

The Dutch tax authority does not simply apply each category's rate to that category's assets. Instead, it calculates a single weighted average deemed return and applies it uniformly to your taxable base. This mathematical approach has important consequences for planning.

Here is the formula in plain terms:

1. Calculate the total deemed return for each category: (savings × 0.36%) + (investments × 5.88%) - ((debts above threshold) × 2.47%)
2. Divide the total deemed return by your total net assets (assets minus debts) to get the weighted percentage
3. Subtract the tax-free threshold (€57,000 per person) from your net assets to get your taxable base
4. Multiply the taxable base by the weighted percentage to get your deemed income
5. Apply the 36% flat rate to the deemed income to calculate your tax

Let us walk through a detailed example. James is a British expat working in Amsterdam. On January 1, 2026, his financial position is:

• Dutch ING savings account: €45,000
• UK Barclays savings account: €35,000 (GBP equivalent)
• Trading 212 stock portfolio: €95,000
• Bitcoin and Ethereum: €25,000
• UK buy-to-let property (Manchester): €220,000 market value
• UK mortgage on buy-to-let: €140,000
• Personal loan (Netherlands): €8,000

Step 1: Categorize assets.
Savings: €45,000 + €35,000 = €80,000
Investments: €95,000 + €25,000 + €220,000 = €340,000
Debts: €140,000 + €8,000 = €148,000 (above threshold: €148,000 - €3,700 = €144,300)

Step 2: Calculate deemed returns per category.
Savings: €80,000 × 0.36% = €288
Investments: €340,000 × 5.88% = €19,992
Debt deduction: €144,300 × 2.47% = €3,564

Step 3: Net deemed return.
€288 + €19,992 - €3,564 = €16,716

Step 4: Net assets.
€80,000 + €340,000 - €148,000 = €272,000

Step 5: Weighted average deemed return.
€16,716 / €272,000 = 6.146%

Step 6: Taxable base.
€272,000 - €57,000 = €215,000

Step 7: Deemed income.
€215,000 × 6.146% = €13,214

Step 8: Box 3 tax.
€13,214 × 36% = €4,757 per year

James pays nearly €400 per month in wealth tax. The heavy weighting comes from the UK property, which is valued at €220,000 with the full 5.88% deemed return -- even though the rental income after costs might be only 2-3%. The mortgage provides some offset but at the lower 2.47% deduction rate, not the full 5.88%.

The €57,000 Exemption: How It Actually Works

The tax-free threshold of €57,000 per person (€114,000 for fiscal partners) is not applied to each category separately. It is subtracted from your total net assets after the weighted average deemed return has been calculated. This means the exemption benefits you at the weighted rate, not at the savings rate or investment rate individually.

For a single person with exactly €57,000 in net assets, Box 3 tax is zero. At €67,000, only €10,000 is taxable. At €157,000, the taxable base is €100,000. The effective tax as a percentage of total wealth is progressive even though the rate itself (36%) is flat, because the exemption shelters a fixed euro amount.

Fiscal partner allocation: one of the most valuable planning tools in Box 3 is the ability for fiscal partners to freely allocate assets between themselves. Even if one partner holds all the investments in their name, they can jointly elect to report 50% each for Box 3 purposes. This is particularly beneficial when it fully uses both partners' €57,000 exemptions.

What Assets Are Excluded from Box 3?

Not everything you own is subject to Box 3. Understanding the exclusions can help you structure your finances more tax-efficiently:

• Primary residence: your main Dutch home and its mortgage are in Box 1
• Pension assets: money in recognized Dutch pension funds, lijfrente (annuity) products, and AOW entitlements are entirely outside Box 3
• Substantial shareholdings: if you own 5% or more of a company (such as a Dutch BV), those shares are in Box 2
• Green investments: qualifying sustainable investments up to an annual cap receive a Box 3 exemption
• Personal possessions: furniture, clothing, a personal car, and household items are not reported
• Certain insurance products: capital insurance policies tied to your mortgage (kapitaalverzekering eigen woning) may be excluded

Year-by-Year Projections: Why They Matter for Long-Term Planning

One of the most valuable features of this calculator is the ability to project your Box 3 tax over multiple years. As your wealth grows through savings contributions, investment returns, and salary accumulation, your Box 3 tax grows as well. Understanding the trajectory helps you plan for the compounding impact of wealth tax on your long-term financial goals.

Consider an expat who starts with €100,000 in investments and adds €1,000 per month. Assuming a 7% annual return on investments and the current deemed return rates, here is a rough projection of their Box 3 tax over time:

These are illustrative estimates. Use the calculator above for a precise projection based on your actual numbers.

Over 20 years, this expat would pay approximately €144,000 in cumulative Box 3 tax. That is a significant drag on wealth accumulation. The tax effectively reduces the long-term compound growth rate of your investments, which is why it is sometimes called "tax drag." For comparison, if the Netherlands taxed only actual realized capital gains (as many other countries do), the tax in years of no selling would be zero.

The Effective Tax Rate: A Key Metric for Expats

When evaluating the true cost of Box 3, look at the effective tax rate on your actual return, not just the statutory 36% rate. Because the deemed return and your actual return often differ, the effective rate can be much higher or lower than 36%.

For example, if your investment portfolio earns 3% in a given year but the deemed return is 5.88%, the effective tax rate on your actual earnings is:

(5.88% × 36%) / 3% = 70.6%

You are effectively paying over 70% tax on what you actually earned. Conversely, if your portfolio gains 12% in a good year:

(5.88% × 36%) / 12% = 17.6%

In that scenario, the effective rate is a very reasonable 17.6%. The deemed return system thus functions as a regressive system in disguise: it disproportionately burdens conservative investors and those in low-return years while effectively subsidizing high-performing portfolios.

The Pending New Box 3 Law: What to Expect After 2027

The Dutch government has committed to replacing the deemed return system with a new law based on actual returns (werkelijk rendement). This has been in development since the 2021 Hoge Raad ruling but has been delayed multiple times due to technical and political complexity.

Under the proposed new system, you would be taxed on:

• Actual interest income from savings
• Dividends received from stocks and funds
• Realized capital gains (from selling investments)
• Unrealized capital gains (mark-to-market on securities, but likely with exceptions)
• Net rental income from real estate

The transition is expected no earlier than 2027, and possibly 2028 or later. For expats, this means you should plan for the current system for at least the next one to two years, while staying informed about developments. The new system may actually increase tax for successful investors while providing relief to savers and those in loss years.

Practical Tips for Expats Managing Box 3 Tax

Based on how the three-category system works, here are actionable strategies for international workers:

• Keep savings and investments in separate accounts: do not hold excess cash in your brokerage account. The tax authority may classify it as an investment rather than savings, costing you the lower deemed return rate.
• Report foreign assets accurately: the Belastingdienst participates in the Common Reporting Standard (CRS), meaning foreign banks automatically report your account information to the Dutch tax authority. Failing to declare foreign assets carries severe penalties.
• Use your pension allowance: maximizing contributions to tax-advantaged pension products (jaarruimte/reserveringsruimte) removes money from Box 3 while providing a Box 1 deduction.
• Time large transactions around January 1: if you plan to sell a property or receive a large bonus, the timing relative to the January 1 reference date can shift thousands of euros of Box 3 tax.
• Consider your departure date: if you leave the Netherlands mid-year, your Box 3 tax is based on the January 1 value of that year. There is no pro-rata reduction for partial-year residency in Box 3.

Frequently Asked Questions

Sources and Further Reading

This information is based on the following official sources:

• Belastingdienst: Box 3 - Tax on savings and investments
• Government of the Netherlands: Income tax
• De Nederlandsche Bank (DNB): Interest rate statistics

The figures and rates mentioned reflect the 2026 tax year. Always verify with the Belastingdienst or a qualified tax advisor for your personal situation.