Why 31 December 2025 is the dividing line
Belgium's capital gains tax on financial assets applies from 1 January 2026 and only taxes value growth from that date. This is why the reference date matters.
Belgium taxes capital gains on financial assets realised from 1 January 2026 onward, but only the increase in value from that date is taxable. This makes 31 December 2025 the reference point that separates untaxed historical value creation from future taxable gains, and establishing that starting value is the practical purpose of a reference-date valuation.
- Only value growth from 1 January 2026 onward is taxable, not historical growth.
- 31 December 2025 is therefore the reference date that fixes the starting value.
- Without a documented starting value, the statutory formula is used instead.
A tax that starts on a specific date
The taxation of realised capital gains on financial assets in Belgium takes effect from 1 January 2026. It does not apply retroactively to value that shareholders built up before that date. The design of the measure draws a clear line between what happened before and what happens after.
For shares in unlisted Belgian companies, this distinction is not automatic in the way it might be for listed securities with a daily quoted price. Someone has to establish what the shares were worth on the day before the rule started applying.
31 December 2025 as the practical reference point
Because the tax targets value growth from 1 January 2026, the value of the shares on 31 December 2025 becomes the baseline against which any future gain is measured. This is the date used as the reference point in an independent valuation report.
A valuation performed for this specific date reflects the company's financial position, results and balance sheet as they stood at that moment, not as they later evolved. This is different from a valuation performed today for a transaction happening today.
What happens without a documented starting value
If a shareholder later sells shares and no independent valuation for 31 December 2025 exists, the statutory formula of equity plus four times EBITDA is applied to determine the reference value, using figures from around that period. This substitutes a mechanical calculation for an actual assessment of the company at that date.
The consequence is that the starting point used to compute any future taxable gain may not reflect the company's real position on that date, particularly for companies with irregular earnings or significant non-operating assets.
The valuation can still be prepared after the date has passed
Establishing the 31 December 2025 value does not need to happen on that exact day. An independent valuation report referencing that date can be prepared later, based on the annual accounts and shareholder records for that period, as long as it is completed within the timeframe allowed for this purpose.
Why the reference date deserves attention now
Shareholders considering a future sale, a family transfer, or simply wanting clarity on their tax position benefit from establishing the 31 December 2025 value while the relevant annual accounts and records are still readily available and verifiable.
Questions on this
Is value built up before 2026 taxed
No. The tax applies only to the increase in value from 1 January 2026 onward. Historical value creation before that date is not covered by this measure.
Why is 31 December 2025 used rather than 1 January 2026
It is the last day before the new tax applies, so it serves as the closing snapshot of value that establishes the baseline for measuring any future taxable gain.
Must the valuation be dated exactly 31 December 2025
The valuation must use that date as its reference point for the company's financial position and results, even if the report itself is prepared and signed at a later date.
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This information is general. It does not take your specific situation into account and is not tax advice.