Capital gains tax on shares 2026: before and after 1 January, with three worked examples

Updated on 26 May 2026 by the by Watson editorial team.

Anyone who watched their ETF portfolio grow quietly over the past few years, or saw their family company build up value, lived in a tax haven. Selling shares at a profit? No tax, provided you were not a speculator. Since 1 January 2026, that calm is over. There is now a capital gains tax of 10% on the table, with a handful of important exemptions that make the difference between a zero-euro tax bill and a serious dent in your proceeds.

At a glance

• Since 1 January 2026, Belgium applies a capital gains tax of 10% on the profit from the sale of financial assets: shares, bonds, ETFs, investment funds, cryptocurrencies.
• The first €10,000 of capital gains per year remains untaxed (annual exemption).
• For anyone with a substantial shareholding of 20% or more in a company, a preferential regime applies: exemption up to €1,000,000, then degressive rates, and 10% above €10,000,000.
• Historical capital gains (built up before 1 January 2026) are exempt, on condition that you have your shares correctly valued as at 31 December 2025, before 31 December 2027.
• Anyone who owns an unlisted company has the most to gain from that valuation. For listed shares, the price on 31 December 2025 is publicly available.

The core rule in one paragraph

Since 1 January 2026 you, as a private investor, owe 10% tax on the capital gain you realise on the sale of financial assets: shares, bonds, investment funds, cryptocurrencies and similar instruments. That tax is due on capital gains above an annual exemption of €10,000. If you have a substantial shareholding (20% or more of the capital of a company), you fall under a separate, more favourable regime with an exemption up to €1,000,000.

What was the situation before 1 January 2026?

Before the new rule came into force, Belgium applied an exemption on capital gains on shares, provided the sale was non-speculative and qualified as normal management of private wealth. In practice: anyone selling shares at a profit paid no tax on the gain, unless the tax authorities could demonstrate that the sale had a speculative character.

That preferential regime was internationally unusual. Most European countries have taxed capital gains on shares for years. The Netherlands has its box 3 system, France a capital gains tax at 30%, Germany a comparable system. Belgium was one of the last with the generous exemption.

‘Until the end of 2025, Belgium was a tax island for capital gains on shares. Since January 2026, the system resembles those of our neighbours, with one important buffer: historical profit remains exempt.’

What changes from 1 January 2026?

Three core rules.

Rule 1: a general rate of 10% on financial capital gains

Every capital gain realised on financial assets above the annual exemption is taxed at 10%. ‘Financial assets’ is broad and includes:

• Shares (listed or unlisted).
• Bonds.
• Investment funds.
• ETFs.
• Cryptocurrencies.
• Certificates, warrants and other financial instruments.

Rule 2: annual exemption of €10,000

The first €10,000 of capital gains per tax year remains untaxed. If your annual exemption is not fully used, part of it (one tenth per year) can be carried forward to subsequent years, up to a maximum of five years. Anyone who realises only €4,000 of capital gains in 2026 can carry €600 (one tenth of €6,000 unused exemption) forward to 2027.

Rule 3: substantial shareholding, a more favourable regime

If you own at least 20% of the shares of a company, you fall under the substantial shareholding regime. This applies above all to entrepreneurs with a substantial holding in their own company, for example a family SME (small or medium-sized enterprise) of which you own 30%, 50%, or 100%.

Within that regime:

• Exemption up to €1,000,000 of realised capital gains.
• Degressive rates for the portion between €1,000,000 and €10,000,000 (see editorial note below: the exact brackets and percentages are to be confirmed by a by Watson tax specialist before publication).
• 10% for the portion above €10,000,000.

For most SME entrepreneurs selling their company, this means that the first million of capital gains remains fully exempt from capital gains tax.

What about historical capital gains from before 1 January 2026?

This is the single most important point for anyone who already holds shares today, especially in unlisted companies.

Principle: the capital gain that had already been built up on 31 December 2025 (the so-called historical capital gain) is exempt from the new tax. Only the gain you realise after 1 January 2026 falls under the new regime.

In practice: to be able to claim that historical exemption, the value of your shares on 31 December 2025 must be correctly established. Otherwise, the tax authorities can say: we do not know which part is historical and which part is new.

The valuation deadline: 31 December 2027

You have until 31 December 2027 to have your shares or other financial assets correctly valued as at 31 December 2025. That is a two-year window. After that date, the exemption is difficult or impossible to claim.

Who should have a valuation carried out?

Most relevant for:

• Shareholders of unlisted companies where no daily share price exists. A valuation by an accountant or auditor is required.
• Holders of investments that are not publicly listed, for example private equity or direct investments.

For listed shares, the price on 31 December 2025 is publicly available. In that case, the valuation is a simple look-up exercise, not specialist work.

What if you miss the deadline of 31 December 2027?

For unlisted shares your historical gain remains theoretically exempt, but in practice you will then depend on a reconstruction based on the last available annual accounts before 1 January 2026. That is almost never the same value as the actual market value, so you run the risk of paying more than necessary.

Recommendation: have the valuation done before the end of 2027.

Worked example 1: John, the small investor

Situation: John bought €30,000 worth of shares in an ETF in 2020. On 31 December 2025 they are worth €50,000. On 31 December 2026 he sells them for €55,000.

Calculation:

• Historical capital gain (€50,000 minus €30,000 = €20,000): exempt.
• New capital gain (€55,000 minus €50,000 = €5,000): falls under the new regime.
• Annual exemption in 2026: €10,000. The €5,000 new capital gain sits within that exemption.
• Tax due in 2026: €0.

Worked example 2: Mary, director selling her company

Situation: Mary owns 100% of a family SME, set up in 2005 with capital of €18,550. On 31 December 2025 the value of her shares (correctly valued) is €1,800,000. On 1 October 2026 she sells the entire SME for €2,200,000.

Calculation:

• Historical capital gain (€1,800,000 minus €18,550 = €1,781,450): exempt.
• New capital gain (€2,200,000 minus €1,800,000 = €400,000): falls under the substantial shareholding regime.
• Substantial shareholding exemption up to €1,000,000: the €400,000 new capital gain sits within that exemption.
• Tax due: €0.

For Mary, the correct valuation as at 31 December 2025 makes a huge difference. Without a valuation, the entire €2,181,450 could be treated as ‘new capital gain’, part of which falls above €1,000,000 and would therefore be subject to degressive rates.

Worked example 3: Tom, the investor who sells early

Situation: Tom bought shares for €25,000 in April 2024. On 31 December 2025 they are worth €40,000. On 15 May 2026 he sells them for €52,000.

Calculation:

• Historical capital gain (€40,000 minus €25,000 = €15,000): exempt.
• New capital gain (€52,000 minus €40,000 = €12,000): falls under the new regime.
• Annual exemption: €10,000.
• Taxable capital gain: €2,000.
• Tax due: €200 (10% of €2,000).

What should you do today, in concrete terms?

Four actions, depending on your situation.

If you own listed shares or ETFs

• Look up the value on 31 December 2025 via public price data. Document this for your tax file.
• On a sale in 2026 or later: your broker will automatically withhold the capital gains tax on sales executed through a Belgian broker. In that case you do not need to declare anything separately.

If you own shares in an unlisted company (your own SME or a private investment)

• Have a valuation as at 31 December 2025 carried out by an expert (accountant or auditor). This is essential if you want to secure the historical exemption.
• Deadline: 31 December 2027.
• On a sale in 2026 or later: the capital gains tax must be correctly reported in your personal income tax return.

If you plan to transfer a company to your children or to a third party

• Think carefully about the substantial shareholding regime. Below 20% you fall under the ordinary rules. Transfers that bring you below 20% cause you to lose the preferential regime.
• Family succession can be tax-complex. Combine this with estate planning and gifting strategies. See also the blog article “Family succession: the quiet two-year preparation”.

If you own cryptocurrencies

• Crypto capital gains fall, as confirmed by the legislator, under the same regime as other financial assets from 1 January 2026.
• A correct valuation as at 31 December 2025 is crucial. Document your portfolio on that date (screenshot, export from your exchange, wallet snapshot).
• Bear in mind that the annual exemption of €10,000 applies to all financial assets combined, not per category.

Frequently asked questions

Does the preferential regime for substantial shareholding always apply?

For entrepreneurs with at least 20% of the shares in the company: yes. The first €1,000,000 of capital gains (after deducting the historical gain) is exempt. Above €1,000,000 degressive rates apply, with 10% for the portion above €10,000,000. The exact bracket structure between €1 million and €10 million is to be confirmed by a by Watson tax specialist before publication.

What happens if I drop below the 20% threshold?

As soon as your stake drops below 20%, you no longer fall under the preferential regime. The ordinary rule of 10% on capital gains above €10,000 per year then applies.

Are losses deductible?

Losses within the same tax year can be offset against capital gains. Unrealised losses can be carried forward up to five years and generate a deduction against future capital gains.

What does ‘normal management of private wealth’ still mean today?

The old exemption based on non-speculative, normal management has been replaced by the new law for financial assets. For other wealth components, such as real estate, the old rules continue to apply.

Does the 10% also apply to companies?

No. This article covers private investors and entrepreneurs with shares in companies. Capital gains on shares within a company have a separate tax regime (the capital gains rule under corporate income tax).

Do I have to declare this myself?

For listed sales via a Belgian broker, the broker withholds the tax and reports it. For other situations (sale of an unlisted company, or foreign brokers), the declaration runs through your personal income tax return.

What if I gift my shares to my children?

A gift is not a realisation of capital gain and does not fall under capital gains tax. Gift duties do apply, and your children take over the acquisition value. Tax planning around transfers is often a combination of gift duties, inheritance tax and capital gains tax. Tailored advice is essential.

Need a valuation or advice on the capital gains tax on shares 2026?

At by Watson we guide you through this valuation process together with independent experts. Our accountants and tax specialists work together to establish the historical exemption correctly. Want to know what the impact is for your situation? Plan a conversation via bywatson.be/contact.