Letter to Parliament on the future of Box 3

Introduction

On 29 September 2026, the government sent a letter to the House of Representatives announcing a reversal of proposed social security cuts, thus providing employers and employees with the opportunity to reach a social agreement. The letter likewise proposes a number of measures to restore purchasing power. The particularly interesting tax issues here are the proposed approach to achieving a future-proof design for Box 3 and the financial coverage required to support this.  

Capital gains regime

In short, the government intends to classify all financial instruments (including shares, bonds and options) under the capital gains regime in Box 3, as early as 2028. Immediately upon the entry into force of the Actual Return Box 3 Act, approximately 90% of assets that appreciate in value would thus already fall under the capital gains regime. Under the original scheme, this already included immovable property. Next, the remaining asset categories (such as savings and cryptoassets) would need to be transferred in 2030, after which box 3 would include a full capital gains tax.

With the current bill already being before the Senate, the government has opted to table a proposal to amend a bill (i.e., a novelle) in the House of Representatives, containing the intended amendments. Once adopted by the House of Representatives, the Senate can proceed to vote on the amended bill.

The government acknowledges the ambitious nature of the timetable and that, particularly in the first year of implementation, the approach taken will place significant demands on both the taxpayers’ ability to comply and the Tax Administration’s capacity to implement the changes. This is because banks are not yet in a position to provide data for the prefilled return.

Financial coverage

The government states that, as the capital gains tax is only levied upon realisation, it will initially lead to less tax revenues than the previously proposed capital growth regime. The following measures are proposed to cover this shortfall:

• To generate additional revenues, the top rate in Box 2 will be reduced by 1.8 percentage points to 29.2% from 2027, for a period of four years. In this way, the government aims to encourage substantial interest shareholders to withdraw ‘tied-up equity’ from their companies.
• The rules on excessive borrowing are being tightened. Starting in 2027, the threshold above which a loan from one’s own company qualifies as a notional regular benefit in Box 2 will be reduced to EUR 100,000 - down from EUR 500,000 - in five annual increments of EUR 80,000. However, loans for the purpose of purchasing owner-occupied property will remain exempt from the rules.
• The fixed yield on other assets in Box 3 will be increased by 1.5 percentage points to 7.87% in 2027, up from 6.37%. The tax-free wealth threshold in Box 3 will be reduced to EUR 30,846 per taxpayer in 2027. This represents a reduction of almost half compared with the current amount (2026: EUR 59,357 per taxpayer).
• The tax-free result under the Actual Return Box 3 Act will be reduced to EUR 1,000 in 2028, down from EUR 1,800. This means more taxpayers will become liable for tax in Box 3.

Purchasing power

The government still sees some financial leeway to somewhat strengthen the purchasing power package for 2027, primarily to make work more rewarding. In this respect the bracket limit above which the top rate of 49.5% applies in Box 1 of income tax will be raised to EUR 80,578 in 2027, up from EUR 78,426. On the other hand, the employment credit will be increased by less than previously announced.

Conclusion

The proposals put forward by the government in its letter to Parliament dated 29 September 2026, must be considered in the context of securing sufficient political support for next year’s budget, including the 2027 Tax Plan, the social security measures and purchasing power, and, not in the least, the future of Box 3. So, whether the measures currently proposed will actually go ahead is still shrouded in uncertainty right now.