Investor's guide to the Belgian capital gains tax

10% tax with €10,000 exemption

In 2025, the new Belgian government reached an agreement for the coalition. As part of it, they agreed to introduce a 10% tax on capital gains for financial assets. A capital gain is the profit you make when you sell an investment for more than you paid for it. Up until now, Belgium did not have a capital gains tax on stocks and equity ETFs.

Fortunately, the first €10,000 of capital gains are exempt.

Starting on 1 January 2026

The tax started on 1 January 2026, even though the law itself will only be formally approved later in the year.

The good news is that it won’t apply retroactively. Any capital gains realised up to 31 December 2025 remain tax-free. In other words, you won’t pay any capital gains tax for 2025, even though you’ll file that tax return in 2026.

All types of financial assets

The tax covers a wide range of financial assets:

• ‍ETFs, as well as index funds, ETNs and ETCs
• Stocks
• Mutual funds
• Bonds
• Currencies
• Commodities like gold. Gold jewellery isn’t covered by the capital gains tax. It stays tax-free as long as you don't trade it for profit.
• Crypto assets, including NFTs
• Financial derivatives like options, futures, and CFDs

Both the assets that you hold within Belgium and outside of Belgium fall under the tax.

€10,000 exemption that can increase to €15,000

The first €10,000 of gains per year per person are tax-free. This amount will be indexed each year, meaning that it will more or less follow inflation

If you don’t use your entire exemption, part of it can be carried forward to the next year:

• Only 1/10 of the annual exemption (so €1,000 if the exemption is €10,000) can be carried forward each year.
• You can accumulate unused portions up to a maximum of five years, meaning the total carry-forward cannot exceed €5,000.
• When you use your exemption in a given year, you must first use the oldest carried-over amounts. This is called the FIFO principle, “first in, first out”.

So if you don’t use your full exemption, you can carry over €1,000 per year, up to a total of €5,000. This allows your maximum exemption to grow from €10,000 to €15,000 if unused for five years.

Example

Let’s say you don’t sell any of your investments in 2026. This means you don’t use your €10,000 annual exemption. The tax rules allow you to carry forward one tenth of that amount, or €1,000, to the next year.

In 2027, your exemption is now €11,000. If you again don’t use it, you can carry forward another €1,000. Your exemption for 2028 then becomes €12,000.

You can keep doing this for up to five years. Each year that you don’t use your exemption, you carry forward €1,000, up to a maximum of €5,000. After five years, your total exemption can therefore grow to €15,000 (€10,000 annual exemption + €5,000 carried over from previous years).

If you then realise a capital gain, the first €15,000 of profit will be tax-free.

Costs and taxes are not included in the capital gains calculation

When you sell an investment, it’s tempting to subtract all the costs and fees to figure out your “real” profit. But for the capital gains tax, that’s not allowed. The law clearly states that no costs or taxes related to buying or selling an asset can be taken into account when calculating your capital gain. This includes broker fees, transaction costs, and the stock exchange tax (TOB). So both your purchase price and selling price are considered gross amounts, before any costs or taxes.

Imagine you buy an investment for €10,000. You also pay €15 in broker fees and €12 in stock exchange tax, so the total amount leaving your account is €10,027.

A while later, you sell the same investment for €13,000. Again, you pay €15 in broker fees and €16 in stock exchange tax, leaving €12,969 on your account.

From your point of view, your profit seems to be €12,969 - €10,027 = €2,942. But for the capital gains tax, those extra costs don’t count. The tax authorities calculate your gain as €13,000 - €10,000 = €3,000. Even though you actually earned a bit less, you’ll be taxed on the full €3,000 gross gain.

You can offset gains with losses

Realised capital gains can be offset against realised capital losses, as long as they were made in the same tax year. So if you made a €10,000 profit on the sale of a stock, but a €15,000 loss on the sale of another, the result is a net loss of €5,000 so you won't be taxed. You can't carry losses forward to future years.

Determining the price of purchase

Snapshot on 31 December 2025 for assets purchased before 2026

According to the government agreement, capital gains earned before the new law takes effect will not be taxed. In other words, profits made before 1 January 2026 will remain tax-free.

To make this possible, the law introduces a special rule for investments that were bought before 2026 but sold after that date. Instead of using the original purchase price to calculate the gain, the law uses the value of the asset on 31 December 2025 as the starting point. This date is referred to as the “snapshot moment” or “photo moment”.

From 2026 onwards, your taxable capital gain will therefore be the difference between the selling price and the value of your investment on 31 December 2025.

Example

You bought an investment in 2022 for €100. On 31 December 2025, it’s worth €150. You then sell it in 2027 for €170.

Your total profit is €70 (€170 – €100). But for tax purposes, only the €20 gain that occurred after 2025 is taxable (€170 – €150). The €50 gain made before 2026 remains completely tax-free.

This rule ensures that the new capital gains tax only applies to profits made after the law takes effect, not to gains built up in previous years.

When your original purchase price was higher than the 2025 value

In most cases, the value of your investments on 31 December 2025 will be higher than what you originally paid. That means you have an unrealised gain at the so-called “snapshot moment”.

But the opposite can also happen. If the original purchase price of your investment was higher than its value on 31 December 2025, you have an unrealised loss at that date.

The law allows an exception in this situation. When you eventually sell the investment, you can use your higher original purchase price instead of the lower 2025 value when calculating your taxable gain. This ensures you’re not taxed on earlier losses that happened before the new capital gains tax came into effect.

For example, imagine you bought shares in 2024 for €200. By 31 December 2025, their value has dropped to €150. You then sell them in 2027 for €210. Under this exception, you can use your original purchase price of €200 instead of the lower 2025 value of €150. So your taxable gain is calculated as €210 – €200 = €10. Without this rule, you would have been taxed on €210 – €150 = €60.

There is a key condition to remember: this exception only applies to sales made up to 31 December 2030. From 1 January 2031, the exception expires. After that, the 31 December 2025 value will always be used as the reference point, even if your original purchase price was higher.

And if you sell the investment after 1 January 2026 at a loss, you can only deduct the loss that occurred after the snapshot date. Losses from before 2026 won’t be recognised for tax purposes.

Selling is in FIFO order

When you invest regularly in the same asset, for example by buying the same ETF every month, you’ll likely own multiple batches of that investment bought at different prices.

To calculate your capital gain when you sell, the tax authorities apply the “First-in, First-out” (FIFO) principle. This means that when you sell part of your holdings, the shares you bought first are considered the ones you sell first. So, for each sale, your purchase price is based on the oldest units you still hold in your portfolio. This rule determines which part of your investment is taxed and how much the taxable gain will be.

Example

Let’s say you bought the same financial asset three times:

• 10 shares at €100 each in 2026
• 20 shares at €150 each in 2027
• 70 shares at €200 each in 2028

Later in 2028, you sell 25 shares for €200 each. According to the FIFO rule, the first 10 shares sold are from your 2026 purchase, and the next 15 shares are from your 2027 purchase. Your taxable gain is therefore:

• 10 × (€200 – €100) = €1,000
• 15 × (€200 – €150) = €750

Total taxable gain: €1,750

The crucial point is that you have no choice. Even if you would prefer to sell the more recent shares, which would typically yield less profit, the tax authorities strictly apply the FIFO principle.

Weighted average purchase price for investments bought before 2026

There is one extra rule if you bought the same asset several times before 1 January 2026. For those “old” purchases, you don’t use FIFO to determine the purchase price. Instead, you must use one weighted average purchase price per asset. This is an exception to the FIFO rule explained above, which only applies from 2026 onwards.

In practice, all your pre-2026 purchases of the same stock or ETF are grouped into one pool with a single average price per unit.

Example

Suppose you bought shares of ETF ABC before 2026:

• 2022: 100 shares at €50 → €5,000
• 2023: 200 shares at €60 → €12,000
• 2024: 150 shares at €70 → €10,500

In total:

• 450 shares
• total cost €27,500

Your weighted average purchase price is:

€27,500 ÷ 450 = €61.11 per share

For tax purposes, all 450 “old” shares are treated as if you bought them at €61.11 each.

Now say the price on 31 December 2025 (the snapshot date) is €80 per share, and in 2028 you sell 200 shares at €90.

For those 200 shares:

• Value on snapshot: 200 × €80 = €16,000
• Sale value: 200 × €90 = €18,000

Your taxable capital gain is only the part after 2025:

€18,000 − €16,000 = €2,000 taxable gain

The profit between €61.11 and €80 was built up before 2026, so it stays tax-free.

If you also buy more of the same ETF after 2025, those new purchases follow the normal FIFO rule explained above. When you sell, the oldest shares (the pre-2026 pool with the weighted average) are considered sold first, and the newer post-2025 purchases are only used once the old pool is exhausted.

Converting foreign currencies

When you buy or sell investments in a currency other than euro, Belgian tax law requires you to convert both the purchase price and sale price into euro. You must use the exchange rate that applies at the exact moment of the transaction, meaning the rate on the day you buy or sell.

From our own experience, this can feel confusing when exchange rates move a lot. But it matters, because the tax authorities always look at your gain in euro, not in the original currency.

Example

Imagine that in 2026 you buy American shares for $1,000, at a time when the exchange rate is 1 euro = 1.11 dollars. Your purchase value in euro is:

$1,000 dollars / 1.11 = €901

In 2028, you sell the same shares for $1,200. The exchange rate at that moment is 1 euro = 1.20 dollars, so the sale value in euro is:

$1,200 / 1.20 = €1,000

Your capital gain is €99, which is the difference between:

• Sale price: €1,000
• Purchase price: €901

Even though the shares went up in value in dollars, only the gain in euro matters for Belgian capital gains tax.

You must be able to prove the purchase price

If you can’t show how much you originally paid for an investment, the Belgian tax authorities assume your purchase price is zero. This means the full amount you receive when you sell is considered a taxable capital gain.

This can become a real problem for crypto investors. Exchanges have gone bankrupt or disappeared, wallet-to-wallet transfers rarely have proper documentation and self-custody makes tracking harder than you’d expect. Many early investors simply don’t have the records they need.

How the tax is collected by brokers and platforms

The way the tax is collected depends on where your broker or investment platform is based. The rules differ between Belgian and foreign platforms. And even among Belgian ones you’ll have the option to “opt out” of automatic tax withholding.

There are essentially three systems:

1. Belgian brokers with automatic tax withholding (opt-in)
2. Belgian brokers with “opt-out”: no tax withheld
3. Foreign brokers: no withholding at all

1. Belgian brokers with automatic tax withholding (opt-in)

If you invest through a Belgian broker, bank, or investment platform, capital gains tax will usually be withheld automatically when you sell an investment with a profit. This is called withholding at source.

In practice, your broker deducts 10% of the capital gain at the moment of sale and transfers it directly to the Belgian tax authorities. At the end of the year, you receive a tax statement that lists your sales and the tax already withheld.

This system has what’s called a liberating effect. Because the tax is already paid, you don’t need to declare these capital gains again in your tax return.

A system that isn’t live yet

There’s an important caveat. Brokers won’t actually start withholding the tax until the law is formally passed, which is expected later in 2026.

By announcing the tax before its legal framework is fully approved, the government has created a confusing situation. On paper the tax exists, but in practice brokers can’t apply it yet.

Why automatic withholding isn’t perfect

Even once withholding is active, the system has some clear limitations:

• Losses aren’t taken into account. Your broker won’t offset capital gains with losses, even though the tax rules allow this.
• The €10,000 yearly exemption is ignored. Even if your total gains for the year are below €10,000, the broker will still withhold 10% on each profitable sale.
• The 31 December 2025 snapshot applies by default. Brokers will calculate gains using the snapshot price, even if you bought the investment earlier at a higher price.

This isn’t because brokers are being difficult. They simply don’t have a full view of your situation. They can’t see what you’re doing with other brokers or platforms. So by law, they must assume the worst case and withhold the full tax on every sale.

An interest-free loan to the government

If too much tax is withheld, you can reclaim the difference through your annual tax return. But that comes with two downsides.

First, it can mean complex calculations on your end. Second, it can take a long time before you see the money again. Here’s how that plays out in practice.

Imagine that in January 2026 you sell an ETF with a €7,000 capital gain. It’s your only sale that year. Because the first €10,000 of gains per year are tax-free, your final tax bill should be zero.

But at the moment you sell, your broker doesn’t know whether you’ll make more sales later in the year. So they must assume the gain is taxable and withhold 10%. That’s €700 deducted immediately.

You can reclaim that €700 through your 2026 tax return. But you’ll only file that return around June 2027. And the refund may not arrive until mid-2028.

So while automatic withholding makes things simpler upfront, it can also mean giving the government an interest-free loan for up to two and a half years.

2. Belgian brokers with “opt-out” (no tax withheld at source)

To avoid this prepayment problem and the other limitations of tax withholding, the law gives you the option to “opt out” of automatic withholding. If you choose this option before the start of the tax year, your Belgian broker will not withhold the 10% tax at the moment of sale. Instead, you’ll have to report and pay the capital gains tax yourself through your annual personal income tax return.

Why you may prefer to opt out

Opting out can make sense if:

1. You want to offset losses. For example, when you made gains on some investments but losses on others. You can only do this through your tax return.
2. You bought assets before 2026 at a higher price. You might be allowed to use your original purchase price instead of the lower snapshot value, which reduces your taxable gain.
3. You don’t want to wait up to two and a half years to reclaim a refund, like in the example above.

You do the calculations yourself

When you opt out, the responsibility shifts to you. You’ll need to calculate your taxable gains yourself, or ask an accountant to help.

Less anonymity, more scrutiny

There’s one important downside to opting out. When you declare your capital gains yourself, you lose the discretion that comes with automatic withholding. With opt-in, brokers withhold the tax and pay it to the tax authorities in blocks. But when you opt out, you must declare every taxable transaction directly to the tax authorities.

This gives the tax authorities detailed insight into your investments. For instance, based on this information, they can decide that you’re no longer investing according to the prudent person principle. If that happens, your gains can be taxed at a much higher 33% rate instead of 10%.

Also not live yet

Just like the Belgian brokers aren't ready yet for the automatic withholding, they also haven't put in place the opt-out system yet. You can expect an email from your broker once it's ready.

3. Foreign brokers: no withholding at all

If you use a foreign broker, such as DEGIRO, Trade Republic, or another platform without a Belgian branch, the situation changes completely.

Foreign brokers are not required to withhold the Belgian capital gains tax. They’ll simply ignore it. There’s also no guarantee that a foreign broker will provide a tax statement compatible with the Belgian system.

This means you’ll likely have to:

• Calculate your gains and losses yourself, for every transaction.
• Keep records of all your purchases and sales.
• Declare everything correctly in your annual tax return.

This can be time-consuming and complex, especially if you invest regularly or use multiple platforms.

Comparison: how brokers handle the capital gains tax

The key takeaways are:

• Belgian broker with withholding: easiest option, but you might temporarily overpay and wait for a refund.
• Belgian broker with opt-out: more control and faster access to your money, but you’ll need to file the tax yourself.
• Foreign broker: full DIY without withholding and most likely no help (except for Curvo!).

The exit tax when you move out of Belgium

If you live in Belgium and decide to move to another country, you may be affected by what’s called the exit tax.

When you move your tax residence out of Belgium, the law assumes that you’ve “sold” all your investments at that moment, even if you haven’t actually sold anything. This means that any unrealised gains (profits that only exist on paper) built up since 1 January 2026 are taxed as if they were realised.

In short: when you leave Belgium, you may owe tax on profits you haven’t actually cashed in.

You don’t have to pay immediately if you move within the EU or EEA

The good news is that Belgium recognises how unfair this would be for people who move frequently for work, especially EU citizens and foreign professionals.

If you move to a country that is part of the:

• European Union (EU),
• European Economic Area (EEA), including Norway, Iceland, and Liechtenstein, or
• any other country with a tax treaty that includes information exchange and cooperation with Belgium,

then you’ll automatically get a deferral. This means you don’t have to pay the exit tax immediately when you leave Belgium.

Example: an EU employee moving abroad

Let’s say you work for a European institution in Brussels and plan to move to Luxembourg in 2026 for a new role. You own a portfolio of ETFs that has increased in value since 2026.

Normally, leaving Belgium would trigger the exit tax, because you’re moving your tax residence abroad. But since Luxembourg is an EU country, your tax payment is automatically deferred. You won’t have to sell your investments or pay tax on them when you move.

As long as you don’t sell those investments within two years, and you continue to live in the EU, the tax obligation will expire after 24 months. You never actually pay the exit tax.

The 24-month “monitoring period”

When you move, the tax deferral lasts for 24 months. During that time:

1. You can’t sell the investments covered by the deferral. If you do, the tax becomes due immediately in Belgium.
2. You can move again within that period (for example, from Belgium to France, then to Germany), as long as you stay within the EU, EEA, or a treaty country.

Each year, you’ll need to send a short confirmation to the Belgian tax authorities showing that you still meet these conditions. If you forget, the deferral ends and the tax becomes payable.

If you move to a country outside the EU or EEA, or one without a qualifying tax treaty, the deferral isn’t automatic.You can still request a delay in payment, but you’ll need to provide a financial guarantee, such as a bank deposit or bond, to cover the potential tax amount.

When does the exit tax expire?

After 24 months:

• If you’ve returned to Belgium, and you didn’t sell the investments, the exit tax is cancelled.
• If you’ve remained abroad, and still hold the investments, the tax obligation expires. You won’t owe anything.

Key takeaway

For most foreigners living and working in Belgium, especially those who may move elsewhere in Europe, the exit tax won’t create an immediate cost. If you move to another EU or EEA country, your payment is deferred automatically, and the tax liability disappears after two years if you don’t sell your investments. But if you plan to move outside Europe, or forget to meet the reporting conditions, you could face a real tax bill on paper gains. So it’s smart to prepare before you leave Belgium.

Strategy for Belgian ETF investors

The capital gains tax may change a few practical details for ETF investors in Belgium, but it doesn’t change the core principles of good investing.

Tax-loss harvesting only if it makes sense

Some investors might be tempted to sell ETFs at a loss to offset other gains and lower their tax bill. This can work, but it comes with transaction costs, stock exchange tax, and the risk that you’ll miss out on future gains if the market rebounds soon after you sell.

In practice, it’s hard to get right. And it goes against the mindset of a diligent buy-and-hold investor, where you invest calmly, avoid tinkering, and let time do the work.

Stick to the fundamentals

Even with the new tax, the key principles of long-term investing don’t change:

• Invest regularly in globally diversified ETFs.
• Stay invested regardless of what the market is doing.
• Follow a disciplined strategy of investing part of your income very month.

The new tax might affect how your broker handles transactions, but it doesn’t change why ETF investing works. The most successful investors are still those who buy, hold, and let compound growth do its job, all while relaxing.

Conclusion

The capital gains tax adds a new layer to investing in Belgium, but it's not the end of the world. With a €10,000 exemption that you can even build up over time, and the ability to offset losses against gains, many of you will barely be affected in practice.

What does change is the admin. You'll need to keep better records of your purchases and sales. You may have to reclaim overpaid tax through your annual return. And if you invest through a foreign broker, you'll be doing all the calculations yourself. These aren't dealbreakers, but they are real hassles.

The good news is that platforms are adapting. Some will withhold the tax automatically. Others, like Curvo, will provide clear guidance and help you report correctly. Either way, the goal stays the same: build wealth steadily by investing in diversified index funds and staying invested for the long term. That's what creates real returns, not clever tax tricks.