Box 3 from 2028: the proposed tax on unrealised gains explained

Short answer

The bill proposed for Box 3 from 2028 uses a wealth-accretion tax as its main rule. It would count not only interest, dividends and rent, but also positive or negative changes in value during each calendar year. Listed shares could therefore create taxable income before the gain is realised through a sale.

This is not current law. The House of Representatives passed the bill on 12 February 2026. After its debate on 30 June, the Senate postponed the vote while awaiting announced amendments.

Today’s Box 3 and the 2028 proposal

Until new legislation takes effect, the Dutch Tax Administration generally calculates Box 3 with deemed returns. If your actual return is lower, the counter-evidence rules let you report that actual return. The lower result is then used.

Value changes can also count under today’s counter-evidence method. The 2028 proposal is therefore not the first setting in which an unsold gain matters. The difference is that actual return would become the structural main system, with its own rules for costs and loss relief.

Wealth accretion versus capital gains

The concepts sound similar, but the taxing point is different.

Under the current bill, wealth accretion is the main rule. Real estate and qualifying interests in startups and scale-ups would generally follow capital-gains treatment. Ordinary income such as rent or dividends remains taxable in the year it is received.

Why is taxing a paper gain controversial?

The gain has not produced cash

An investment may be worth more on 31 December without providing cash to pay tax. A taxpayer might need other funds or may have to sell part of the investment. This liquidity concern is strongest for sharply rising but illiquid assets.

A gain can disappear later

A rise in year one may be followed by a fall in year two. The proposal contains loss relief, but the exact sequence, time limits and transition rules matter. A multi-year outcome can feel different from taxing one realised sale profit.

Valuation and administration become more complex

Tradable securities normally have a market price. Less liquid assets are harder to value. The Council of State also raised concerns about clarity, taxpayer manageability and the administration of a mixed system.

Why does the government still prefer wealth accretion?

The government points to practical and policy advantages:

• annual taxation limits long-term deferral;
• banks and brokers already report much of the data for liquid assets;
• the proposal allows losses to offset later positive results;
• tax becomes less dependent on a taxpayer choosing when to sell.

A full capital-gains tax is less likely to create tax before sale, but it can encourage deferral and planning around the disposal date. The debate is therefore about administration and behaviour as well as fairness.

Three simplified examples

These examples only explain the mechanism. They are not personal calculations and omit exemptions, costs, debts, rates and detailed loss rules.

Shares rise

A portfolio rises from €100,000 to €112,000 during the year and pays €2,000 in dividends. Under the proposed main rule, the result broadly includes the €12,000 increase plus €2,000 of dividends, even if no share was sold.

Shares fall

If the same portfolio falls from €100,000 to €92,000, it has a negative value result. The bill provides for relief against positive results in other years, subject to the final statutory conditions.

A second home

The proposed treatment of a second home is different: its increase in value would generally follow capital-gains treatment and be taxed on sale. Rent and own-use rules can still create an annual result before that sale.

What remains uncertain?

The target date is 1 January 2028, but parliamentary consideration has not finished. The government is exploring amendments within the wealth-accretion model and is also studying a broader capital-gains alternative. Possible changes may appear in the 2027 Tax Plan.

Do not base a financial decision on one modelled 2028 outcome. Calculations for 2026 remain subject to the current deemed-return and counter-evidence rules.