US Brokerage Account in the Netherlands: 2026 Box 3 Tax Rules

Box 3 is where a Dutch-resident American's US portfolio meets the most distinctive idea in Dutch income tax: taxing wealth's assumed yield instead of its actual one. In a year when the account soars, Box 3 can be gentle; in a year when it falls, Box 3 still computes a positive deemed return - which is precisely the tension the Dutch courts have been working through since 2021.

This article is aimed at US citizens and green-card holders resident in the Netherlands who hold US brokerage or investment accounts, and at the professionals who prepare their returns on both sides. It sets out how Box 3 works for 2026 as published, dates the transition from deemed to actual returns precisely, and describes - factually, with no planning devices - how a US account sits between the two systems.

This article describes how United States federal tax law and the U.S.–Netherlands income tax treaty apply to US persons. It summarises Dutch rules only as published by the Belastingdienst and in theStaatsblad, for context, and is not Dutch tax, legal or succession advice - those questions belong with a Dutch-qualified professional.

How Box 3 works for 2026, as published

Box 3 (income from savings and investments - inkomen uit sparen en beleggen) taxes a deemed return on the value of assets and debts as they stood on 1 January. For 2026 the Belastingdienst publishes a6.00% deemed return on investments and other assets — a percentage it states is already definitive - provisional percentages of 1.28% for bank deposits and2.70% for debts, a 36% rate, and a tax-free allowance of €59,357 per person.

Two disciplines keep those figures honest. First, the year label: 2025's percentages were different (1.37% bank deposits,5.88% investments, 2.70% debts, €57,684 allowance), and the bank-deposit and debt percentages for any year are set only after it ends - they stay provisional until then. Second, the parliament label: the 2026 figures that were widely reported from the original Belastingplan 2026 proposal - a 7.78%investment for fait and a reduced €51,396 allowance - are not the published law; the enacted figures are the 6.00% and €59,357 above. Quoting Box 3 without a year and a source is how portfolios get mis-planned.

The computation itself runs in published steps: each asset category is multiplied by its percentage to produce a taxable return; assets and debts are netted into a yield base; the allowance comes off; and the resulting share of the deemed benefit is taxed at 36%. The point to hold onto is that no step asks what the account actually earned - that question enters only through the counter-evidence rule described below, and through the system parliament intends to build for 2028.

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From deemed to actual returns: the dated story of a regime in transition

The dates carry the meaning. On 24 December2021 the Hoge Raad's kerst arrest held the then Box 3 system contrary to the European Convention on Human Rights, forcing rechtsherstel and bridginglegislation. On 6 June 2024 the court went further - in the Belastingdienst's words, it ruled "dat het Rechtsherstel en de Overbruggingswetgeving instrijd is met het Europees Verdrag voor de Rechten van de Mens" - where the deemed return exceeds the actual one.

The 2024 rulings also defined the yardstick. The government's own summary of the arresten: taxpayers with a lower actual return than the assumed one "moeten de gelegenheid … krijgen ditaan te tonen," with actual return covering "zowel het directerendement, zoals rente, huur en dividend als het indirecte rendement, zoals(on)gerealiseerde waardestijgingen en waardedalingen van het vermogen" - direct income plus realised and unrealised value changes.

Parliament then wrote the court's yardstick into statute. The Wet tegenbewijsregeling box 3 passed the Tweede Kamer on 12June 2025 and the Eerste Kamer on 8 July 2025, and entered into force on 19July 2025. Under it, the deemed-return computation applies unless your actual return is lower and you report it: for 2024 and earlier years via the formOpgaaf werkelijk rendement (OWR), and from tax year 2025 within the aangifteitself. The Belastingdienst applies whichever computation favours you - "Wij rekenen met het meest gunstige rendement voor u."

Actual return under the statute is deliberately broad and deliberately bare: it is computed over your total assets with no tax-free allowance, it includes unrealised movements, and costs are not deductible - with published exceptions for interest on Box 3 debts and certain capitalised property improvements. Which back years remain open on a given taxpayer's facts depends on the state of their assessments and objections, and this article deliberately states no rule for that: it is a file-by-file question for a belastingadviseur. Whether to invoke the counter-evidence rule at all - gathering a year's statements across accounts and currencies to prove a return - is likewise a question to take to the professionals, not a step this article recommends.

The endpoint is before parliament, not yet law. The wetsvoorstel Wet werkelijk rendement box 3 went to the Tweede Kamer on19 May 2025 and was adopted there on 12 February 2026; the Eerste Kamer debatedit on 30 June 2026 and postponed its vote pending announced amending legislation, so it must still decide. The government's stated intention is a start on 1 January 2028, taxing actual income plus asset growth - with a realisation-based rule for real estate and startup shares - while theBelastingdienst's own pages hedge the date ("waarschijnlijk per 1 januari2028"). Until enactment, the bridging regime plus the counter-evidence rule are the law.

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Where a US brokerage account sits: deemed return meetsactual taxation

For a Dutch-resident American the two systems tax the same account on different theories. The securities in a US brokerage account fall, as a category matter, within Box 3's investments class - a 6.00% deemed return for 2026 - while the United States taxes the account's actual dividends, interest and realised gains under the Code, PFIC rules aside. Neither system asks how the other one defined the income.

The mismatch cuts both ways, which is why this article states it without adjectives. In a strong year, actual US-taxed gains can exceed the Dutch deemed 6.00%; in a weak year, Box 3 computes taxable income the United States never sees - the exact situation the counter-evidence rule was written for, since a provable lower actual return caps the Dutch side. The 1 January reference date adds a timing layer: the Dutch snapshot is one day, while the US measures flows across the whole year.

The cross-border plumbing is thinner than readers expect, and this series says so plainly. On US-source dividends, Article 10(2) of the U.S.-Netherlands Income Tax Treaty caps source-state tax at 15% for portfolio holders; the Belastingdienst's return guidance confirms foreign withholding may be credited "tot een bepaald maximum" - up toa maximum - in the aangifte. Beyond that, the treaty's relief articles could not be retrieved in full from the official texts located for this series, and whether the Box 3 levy itself is a creditable foreign income tax on the US side is addressed in no located primary source. Both credit directions — Dutch relief for US withholding, and any US foreign tax credit for Dutch tax - are therefore presented as the professionals' computation on each year's facts.

One transitional footnote belongs here because it decides who is in Box 3 at all: 30%-ruling holders who first held the ruling before 2024 can, through the 2026 return only, still elect partial foreign tax liability and keep non-Dutch investment assets out of Box 3 - an election abolished for everyone else from 2025. The dates, cohorts and mechanics are in this series' 30%-ruling article; if that election has carried your account so far, the Box 3 rules above describe what its published expiry brings.

The calendar makes the mismatch a working reality every spring. The Dutch aangifte must, in invitation cases, be received before 1 May, built on the 1 January snapshot in euros; the US return runs to its own deadlines on the year's actual dollar flows, with the automatic two-month extension for Americans abroad; and a migration year is filed in the Netherlands on the M form (M-biljet), which handles part-year residence. A household that reconciles its US year-end statements to a 1 January euro valuation once, carefully, spares both preparers the same untangling every year after.

Funds, platforms and the rest of the account map

What the account holds matters as much as where it sits. Dutch or EU-domiciled funds - UCITS among them - held by a US person will typically meet the passive foreign investment company tests of Section 1297, the 75% income test or the 50% asset test, bringing Form 8621'sregimes with them on the US side; US-domiciled funds inside a US brokerage account do not raise that problem. The PFIC mechanics live in this series' dedicated piece (/pfic-ucits-funds-foreign-nationals-us-residents).

Two practical companions complete the map without being restated here: whether a US brokerage will keep serving a Netherlands address - and the sequencing if it will not - is covered in/us-brokerage-closing-expat-accounts, and the euro–dollar dimension of measuring one portfolio in two currencies (the Dutch snapshot in euros on 1January, the US year in dollars) is covered in/currency-americans-switzerland-uk-eurozone. FBAR and Form 8938 reporting continue throughout on the US side, whatever Box 3 does.