Box 3 for Share and ETF Investors: What's Actually Taxed in the Netherlands
Box 3 is difficult for foreign investors to understand because it does not behave like a conventional capital-gains tax. Under the standard 2026 calculation, the Netherlands taxes a deemed return on the net wealth in Box 3 rather than simply taxing the dividends and realised gains that arrived in the brokerage account.
The 2026 standard calculation
For 2026, the tax-free wealth allowance is EUR 59,357 for an individual and EUR 118,714 for tax partners together. Above the allowance, the system applies notional return percentages by asset category and then taxes the calculated Box 3 income at 36%.
For the 2026 provisional assessment, the Belastingdienst uses 6.00% for investments and other assets such as shares and ETFs. The provisional percentages for bank balances and debts are 1.28% and 2.70% respectively; the Belastingdienst notes that the latter two are provisional until finalisation. Values are measured at the 1 January reference date for the standard calculation.
That can produce tax in a bad market year
Under the standard method, a portfolio can fall during the year and still have a positive deemed return because the tax is not calculated from that portfolio's actual annual performance. That mismatch is the reason Box 3 has been subject to major court challenges and legislative change.
The tegenbewijsregeling changes the comparison
Following Supreme Court decisions and subsequent legislation, taxpayers can provide their actual return when it is lower than the deemed return. The Belastingdienst describes actual return broadly: interest and dividends plus changes in the value of assets, including unrealised changes.
The authority then uses the more favorable result where the actual-return rules apply. One important nuance is that the tax-free wealth allowance used in the standard method is not simply deducted in the same way when calculating actual return. The two methods are therefore not interchangeable percentage calculations.
What happens to foreign dividend withholding
Foreign dividend withholding can still matter even though Box 3 does not tax dividends as a separate income category. Relief depends on the applicable double-taxation rules and on the amount of Dutch tax available to absorb the credit. Excess foreign withholding may not be immediately usable in the same year and can require carry-forward treatment under the relevant rules.
That is why investors should keep source-country withholding records even when the domestic tax is wealth-based rather than dividend-based.
The planned 2028 system is not final law yet
The government continues to work toward a system based more directly on actual returns from 1 January 2028. The bill passed the Tweede Kamer in February 2026 and was debated in the Eerste Kamer in June, but as of 31 August 2026 the legislative process was still not complete and amendments remained under discussion.
For 2026 and 2027 planning, investors should therefore work from the rules that actually apply now, including the standard deemed-return method and the actual-return counter-evidence route, rather than budgeting from a future regime that may still change.
The practical takeaway
For a Dutch share or ETF investor, the key inputs are the 1 January asset values, the category of each asset, the applicable allowance and deemed-return percentages, and - if the actual-return route may be beneficial - a defensible record of dividends, interest and value changes across the year.
Box 3 is not a tax you can understand from a brokerage P&L alone. It is a balance-sheet calculation with a second, increasingly important actual-return comparison layered on top.