I. Introduction: from political intention to legislative reality
For decades, Belgium has been an outlier in Europe by not levying a general capital gains tax on financial assets held as private wealth. That exceptional position is now formally coming to an end.
With the filing in Parliament on 17 December 2025 of a 272-page bill introducing a capital gains tax on financial assets, the discussion has clearly moved from political announcements and leaked drafts to a concrete legislative framework. Since early January 2026, the bill is being examined in the Parliamentary Finance Committee, where it has already become clear that the discussions will be extensive and technically demanding.
According to press reporting, additional expert hearings will be organised in the coming weeks, and multiple parliamentary sessions will be needed to scrutinise the bill in full. The political objective, as stated by the government majority, is to conclude the parliamentary process by the end of the February recess, allowing the regime to enter into force as planned for capital gains realised as from 1 January 2026.
This update builds on the published bill and places it in its broader fiscal and political context, while highlighting the practical consequences for taxpayers.
II. Policy rationale and political framing
A. “Normalising” Belgium in a European context
In the parliamentary debate, the Minister of Finance has repeatedly stressed that Belgium is one of the very few remaining countries without a general capital gains tax on financial assets. The introduction of such a tax is presented as a matter of tax system “normalisation” rather than a radical reform.
At the same time, the capital gains tax is explicitly framed as a budgetary and social rebalancing instrument. According to figures cited by the government:
- the tax is expected to raise approximately EUR 250 million in its first year,
- and around EUR 500 million annually once the regime reaches cruising speed.
Those proceeds are politically earmarked to support a reduction of the tax burden on labour, reinforcing the narrative that capital should contribute more where labour is already heavily taxed.
B. Focus on wealthier taxpayers
Another recurring element in the parliamentary narrative is that the tax would predominantly affect the top 1% wealthiest households. This claim is based on internal studies by the Federal Public Service Finance and is clearly intended to counter concerns that the tax might disproportionately affect middle-class savers.
That said, the breadth of the definition of “financial assets” and the relatively low general rate (10%) combined with limited exemptions means that, in practice, a much wider group of taxpayers will need to engage with the new rules, even if the highest revenues are expected to come from larger portfolios and substantial shareholdings. It is to be seen in the published revenue numbers after the first year of applications, if this statement is true, given the fact that there still are plenty of ways for wealthier taxpayers to structure their fortune in a way that the capital gains tax doesn’t apply.
III. Scope of application: who and what is targeted?
A. Personal income tax as the main entry point
The capital gains tax is primarily designed as a personal income tax measure, targeting gains realised outside any professional activity. Such gains are categorised as miscellaneous income, separate from professional income and ordinary investment income subject to withholding tax.
The regime also extends to certain entities subject to the legal entities tax, though with specific exclusions and interaction rules, notably in the context of donations and non-profit structures.
Corporate income tax payers are not the main target of the reform; the bill is clearly focused on private wealth situations, whether held directly or through common investment structures.
B. A broad notion of “financial assets”
The bill adopts a deliberately broad definition of taxable assets, including:
- listed and unlisted shares,
- bonds and other debt instruments,
- investment funds and trackers,
- certain insurance-based investment products,
- crypto-assets and currencies,
- and investment gold.
This breadth is a key reason for the length and complexity of the bill and explains why the parliamentary discussions are expected to be particularly detailed.
IV. Taxable event: realisation remains key
A central design choice is that only realised capital gains are taxable. The tax is triggered by a transfer for consideration, such as a sale or exchange.
This concept remains crucial for structuring:
- pure gifts, successions and certain reorganisations may fall outside the realisation concept,
- but mixed transactions or structures involving indirect consideration may still trigger taxation.
The distinction between realised and unrealised gains also underpins the design of the exit tax (see below).
V. Valuation mechanics: documenting the 31 December 2025 reference value
One of the most sensitive and practically important aspects of the new capital gains tax is the determination of the reference value as at 31 December 2025 for assets acquired before 1 January 2026. While the political debate has often focused on rates and exemptions, the valuation rules will, in practice, be decisive for the effective tax burden and for dispute risk.
A. Listed financial assets: reliance on objective market data
For listed shares, bonds, trackers and investment funds, the legislator deliberately opts for a pragmatic approach. The reference value may generally be derived from objective market data, such as:
- official closing prices on regulated markets,
- net asset values (NAVs) published by fund managers,
- or standard year-end statements issued by banks and brokers.
In practice, this means that portfolio snapshots as at 31 December 2025 issued by financial intermediaries will play a central evidentiary role. The explanatory memorandum confirms that taxpayers may rely on such documentation to substantiate the reference value, provided it is sufficiently detailed and traceable.
This approach limits valuation disputes for listed assets, but it also places a premium on proper archiving: where statements are missing or incomplete, reconstructing the relevant value years later may prove difficult.
B. Average acquisition value and proof alternatives
Compared to earlier draft texts, the published bill introduces important nuances regarding proof of acquisition value.
While the 31 December 2025 value is the default reference for pre-2026 assets, the bill allows taxpayers, under certain conditions, to rely on:
- an average acquisition value, rather than a strict FIFO methodology,
- or alternative proof where the reference value would otherwise lead to artificial gains.
This is particularly relevant for long-held portfolios that have undergone multiple purchases, reinvestments or restructurings over time. The legislator explicitly acknowledges the practical difficulty of reconstructing historical transactions and seeks to avoid disproportionate compliance burdens.
That said, the flexibility is not unlimited: the burden of proof remains with the taxpayer, and the documentation must be coherent and verifiable.
C. Unlisted shares and private assets: formal valuation routes
The valuation challenge is most acute for unlisted shares, family companies and other private assets for which no market price exists.
Here, the bill introduces a structured valuation mechanism:
- the 31 December 2025 value may be established through a valuation performed by a statutory auditor or certified accountant,
- using generally accepted valuation methods (e.g. DCF, multiples, net asset value, or a combination thereof),
- with a formal deadline extending until 31 December 2027.
This extended timeline is a material improvement compared to the initial political narrative, which suggested a strict year-end 2025 cut-off. In practice, it allows shareholders to:
- take a more measured approach to valuation,
- align valuations with existing financial information,
- and avoid rushed or defensive reports that could later be challenged.
Nevertheless, the valuation date remains 31 December 2025, meaning that the underlying data and assumptions must reflect the situation at that date, even if the report itself is finalised later.
D. Strategic implications of valuation choices
The valuation rules are not merely technical; they can significantly influence tax outcomes and planning options.
For example:
- a conservative valuation as at 31 December 2025 may reduce future taxable gains but increase audit risk if insufficiently substantiated,
- whereas a robust, well-documented valuation may offer stronger legal certainty, even if it results in a higher reference value,
- differences in valuation approach can also affect the interaction with the 20% substantial shareholding regime, exit tax exposure, or future reorganisations.
In that sense, valuation becomes a strategic exercise, not just a compliance step.
Now that the 31 December 2025 reference date has passed, the key question is no longer whether a valuation should be performed, but how defensible it will be in hindsight. For many taxpayers (definitely the ones with unlisted shards) early engagement with valuation specialists and tax advisers will be essential to balance tax optimisation, legal certainty and audit resilience.
E. A likely focal point for disputes
Given the amounts at stake and the inherent subjectivity of valuation, it is reasonable to expect that valuation will become one of the primary points of contention between taxpayers and the tax authorities.
The combination of:
- a fixed historical reference date,
- delayed realisation events,
- and complex valuation methodologies,
means that discussions may arise years after the reference date, when factual reconstruction becomes more difficult. This reinforces the importance of contemporaneous documentation and professional involvement at an early stage.
VI. Rates, exemptions and differentiated regimes
A. General regime: 10% with annual exemption
The general rule is a 10% tax rate, applied after an annual exemption of EUR 10,000 (indexed).
A limited carry forward is provided:
- unused exemption can be carried forward up to EUR 1,000 per year,
- with a cumulative cap of EUR 15,000.
This design reflects a political compromise: a relatively low rate combined with modest relief for smaller, occasional gains.
B. Substantial shareholdings (20%+)
For taxpayers holding at least 20% of the shares in a company, a separate regime applies:
- a EUR 1,000,000 exemption, spread over a five-year period,
- followed by a progressive rate scale from 1.25% to 10%.
This regime is particularly relevant for founders, family shareholders and private equity-style exits, and will likely become a focal point of planning discussions.
C. Internal gains and anti-abuse
Sales within a controlled sphere (“internal gains”) are subject to a 33% rate, reflecting a clear anti-abuse intent. This provision is likely to attract scrutiny during parliamentary hearings, given its potentially broad reach.
VII. Exit tax: mobility under the spotlight
To prevent taxpayers from escaping the tax by emigrating, the bill introduces an exit tax on latent gains when Belgian tax residence is lost.
Deferral mechanisms exist, but the rules are complex and documentation-heavy. For internationally mobile families and entrepreneurs, this element alone justifies early modelling and advice.
VIII. Operational aspects and transitional regime
A. Withholding and opt-out mechanics
The bill further refines the withholding tax system, combined with an opt-out possibility to avoid prefinancing.
A practical but potentially problematic rule is that opt-out must be exercised per securities account, and only if all account holders agree. In family or jointly held portfolios, this may significantly limit flexibility.
B. First half of 2026: a transitional reality
A notable operational feature is that uniform obligations for financial intermediaries are expected to be fully in place only by 1 July 2026. For the first half of 2026, the bill provides for transitional and regularisation mechanisms.
This confirms that, although the tax conceptually applies as from 1 January 2026, compliance in practice will be phased in, increasing the importance of documentation and follow-up during 2026.
IX. Practical takeaways at the start of 2026
Now that the reference date has passed, attention shifts to compliance and structuring. Some first steps can already be taken:
- secure and archive 31 December 2025 portfolio documentation,
- assess whether formal valuations are needed for unlisted assets,
- review joint accounts and opt-out feasibility,
- model the impact of the 20% substantial shareholding regime,
- and factor in exit tax exposure in any mobility planning.
X. Conclusion
The Belgian capital gains tax has clearly entered a new phase. With a detailed bill on the table and parliamentary scrutiny underway, the question is no longer if the tax will be introduced, but how it will operate in practice and how taxpayers should adapt.
While the government emphasises that the measure targets primarily the wealthiest households and serves to reduce labour taxation, the breadth and technicality of the regime mean that a wide range of investors, entrepreneurs and families will be affected.
The coming weeks of parliamentary debate and expert hearings may still lead to adjustments, but the architecture of the system is now visible. For taxpayers, 2026 will be less about last-minute transactions and more about documentation, modelling and forward-looking planning in a fundamentally changed Belgian tax landscape.
