The Belgian capital gains tax has three distinct regimes:

The progressive regime for substantial participation: the first €1,000,000 of gains is exempt. That million is counted over five consecutive tax periods: whatever was already exempted during the four previous periods is deducted from it. On the amount left after the exemption:

• 1.25% up to €2.5 million
• 2.5% from €2.5 to €5 million
• 5% from €5 to €10 million
• 10% above €10 million

Each taxpayer has a base exemption every year on net capital gains: €10,000 for 2026 income. This amount is indexed every year. The 10% tax only applies to gains exceeding the exemption.

Additional exemption

From 2027 income onwards, an additional exemption may be added. It depends on the previous year: if you did not use your base exemption, you get €1,000 (2027 amount, indexed afterwards); if you used less than €1,000 of it, you get €1,000 minus that amount; if you used more, you get nothing for that year.

Unused additional exemptions accumulate from year to year; the law sets no time limit for using them. Only their use is capped per year: about €5,000 (base amount of €2,426, indexed every year; in its examples, the circular takes five times the additional exemption of the year). They are used first, oldest first, before the base exemption.

Married couples / cohabitants

The exemption is personal: one per taxpayer. When an asset is jointly owned by two spouses, each declares half of the gain and uses their own exemption, i.e. up to €20,000 for the couple in 2026.

When you have acquired the same asset at different times and prices, the law mandates the FIFO principle: the first asset acquired is deemed to be the first sold.

Example

Purchases that are not sold stay in the queue from one year to the next: each sale consumes the oldest ones left.

One FIFO per account

If you hold the same asset on several securities accounts, FIFO is applied separately on each account: a sale only consumes the purchases of its own account.

Moving your assets from one of your accounts to another without selling them is not a disposal: no gain is realized and your purchase price does not change.

The application applies FIFO separately on each platform, for each asset. When you move assets from one platform to another, record a transfer: they keep their purchase date and price on the destination platform. Without it, the application cannot match your sales with the right purchases.

The taxable base is the gross difference between the sale price and the acquisition price. No fees or taxes of any kind may be deducted, including:

• Brokerage commissions
• Stock exchange transaction tax (TOB)
• Custody fees
• Valuation costs for unlisted assets

The application displays your fees for informational purposes, but they are excluded from the capital gain calculation in accordance with the law.

Losses realized during the same tax year can be offset against gains, subject to these rules:

• Same taxpayer, same fiscal year
• Same tax regime (losses from ≥20% participation cannot offset gains from the 10% regime)
• Cross-asset is allowed: a loss on stocks can offset a gain on crypto or gold within the same regime
• Losses cannot be carried forward to future years

The application automatically calculates your net result (gains − losses) before applying the exemption.

For assets held before January 1, 2026, the value at December 31, 2025 replaces the original acquisition price. Historical gains (before 2026) are therefore exempt.

Latent loss exception

If your original acquisition price is higher than the Dec 31, 2025 value (latent loss), you may ask for it to be used instead — for sales made up to and including December 31, 2030. Three rules:

• You have to ask for it and you have to prove that price. The statements of your financial institution can serve as proof.
• The price used is the average purchase price of the asset, calculated on the units you still held on Dec 31, 2025 — not the price of each purchase.
• It can bring the gain down to zero, but never create a loss. A loss is always measured from the Dec 31, 2025 value.

The application applies this exception automatically whenever it is in your favour, using the average purchase price per asset of the units still held on Dec 31, 2025. Keep your proof of purchase.

There are two ways to pay the capital gains tax:

1. Bank withholding (default)

Your financial institution calculates and withholds the tax automatically. However, banks cannot take into account your exemption, your losses, or a historical purchase price higher than the Dec 31, 2025 value — you must claim those via your annual tax return, with supporting documents.

This withholding only exists for financial instruments and insurance contracts, and only when an intermediary established in Belgium is involved. Nothing is withheld on crypto-assets, currencies and investment gold: those gains must always be declared.

2. Opt-out (self-declaration)

You can request your bank not to withhold the tax. In this case, you declare all gains and losses yourself in your annual tax return and pay when you receive your tax assessment. For income year 2026, this choice had to be communicated to the bank by August 31, 2026 at the latest.

Timeline

• Jan 1, 2026: Tax takes effect
• Jun 1, 2026: Banks begin automatic withholding
• 2027: First tax return including capital gains (2026 income, assessment year 2027)

This application generates a tax summary PDF that you can use for your annual declaration, available on the Export page.