Valuation of financial assets as at 31 December 2025 – impact of tax reform

In the 2025-2029 federal government agreement and ongoing tax discussions, the treatment of capital gains on financial assets is one of the major changes in the upcoming Belgian tax reform. One of the cornerstones of this project – currently being finalised in legislative form – is the requirement to value financial assets on a reference date: 31 December 2025. This provision will serve as the basis for calculating the taxation of future capital gains, in particular under the regime that is expected to come into force on 1 January 2026.

1. Why a valuation as at 31 December 2025?

The tax reform aimed at taxing capital gains realised outside the professional sphere is based on two principles:

• Avoiding cases of excessive optimisation through artificially low tax bases;
• Ensuring a fair transition between the old regime (no tax on many capital gains) and the new, broader regime.

To achieve these objectives, the legislator proposes to set a reference value for financial assets held on 31 December 2025 — whether shares, bonds, fund units, crypto-assets or other financial instruments. This valuation will become the new basic tax ‘acquisition value’ for the application of capital gains tax after 2026.

2. Which asset categories are affected?

According to parliamentary proceedings and draft bills, the following may be covered by this mechanism:

• Shares and securities of listed and unlisted companies;
• Units in investment funds, SICAVs and ETFs;
• Bonds and debt securities;
• Crypto-assets;
• In certain cases, currencies or precious metals.

The intention is to include all financial assets whose capital gains are likely to be realised outside a professional context, while defining a clear scope of exclusions (e.g. traditional bank accounts that do not generate capital gains, certain real estate schemes, etc.).

3. How will the valuation be determined?

The proposed law envisages a simple rule:

tax acquisition value = the lower of the historical purchase price and the market value on 31 December 2025.

This means that even if you acquired a security at a lower or higher price, your tax base will be the lower of your historical price and the valuation on that reference date. The aim is to avoid both excessive corrections (for those who bought high) and abuse (for those who bought low just before the law came into force). This mechanism is already used in other tax contexts (e.g. depreciation, anti-abuse mechanisms) and is a pragmatic solution for establishing a uniform tax base.

4. Tax implications for taxpayers

For individuals, executives, institutional investors and small savers, this rule has several important implications:

• Greater legal certainty: you know in advance what basis will be used after 2026.
• Relative tax neutrality: those who realised unrealised gains before 2026 will not be taxed retroactively on capital gains already acquired before that reference date.
• Clarity for tax returns: at the time of sale, the difference between the sale price and the 2025 value (if lower than the historical price) becomes the taxable capital gain.
• Reduced risk of litigation: the administration and taxpayers share a single, objective value that serves as the basis for future taxation.

5. Points to note

• Unlisted securities require a reliable valuation method (market indicators or experts).
• The conversion of crypto-assets may require market values that are compatible for tax purposes.
• Intra-group transactions or transfers to non-residents must be carefully analysed to avoid double taxation or unfavourable treatment.