Royal decrees on Belgian capital gains tax published

Per the law of 6 April 2026 (published on 21 April 2026), the Belgian capital gains tax on financial assets has effectively been introduced. (See our previous updates of July, September, December 2025 and April 2026.) Two Royal Decrees have now been published in the Belgian Official Gazette, providing more detail on the withholding tax, exit tax, and reporting obligation for intermediaries.

Withholding tax credit

Financial institutions established in Belgium are generally required to withhold taxes on realized capital gains when they process qualifying transactions. When applying withholding tax, they will not take into account the following rules which may reduce the taxable base:

first-tranche annual exemption of EUR 10,000-15,000 (subject to indexation);
step-up mechanism for historical gains (accrued prior to 1 January 2026);
offsetting qualifying capital losses;

Taxpayers can apply these rules through their personal income tax return. In such cases, the withholding taxes withheld will be off-set against the final tax liability.

In terms of supporting documentation, the Royal Decree introduces explicit evidence requirements for taxpayers. They must be able to document (upon request of the tax authorities):

the amount of the realized gains;
the amount of withholding tax effectively withheld;
where relevant, the historic acquisition value or the total amount of insurance premiums paid up to 31 December 2025; and
where relevant, the amount of capital losses that have been claimed.

Kris Lievens

Partner, Head of Corporate Tax | Tax, Legal & Accountancy

KPMG in Belgium

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Opt-out mechanism

The above-mentioned withholding tax mechanism is ‘optional’. Individual taxpayers can choose to opt out of withholding tax in which case no tax is withheld, and the capital gains are fully settled via the annual personal income tax return. The second Royal Decree specifies the details of this opt-out procedure.

A. Opt-out procedure: details introduced or confirmed by the Royal Decree

Form:

The choice must be made unambiguously and in writing. Both aspects need to be read in their current context and as such also include technologically governed choice processes.
Deadline:

The Royal Decree distinguishes between financial assets and insurance products. For financial assets the choice must be made upon opening an account or by the deadline imposed by the broker which must precede any realizations on the account. For insurance products the choice is due at the latest upon (partial or full) liquidation of the product.

For realizations between 1 June 2026 and 31 August 2026 the opt-out is due by the deadline imposed by the broker, ultimately by 31 August 2026.
Choices past the deadline:

Opt-outs past the deadline will apply only as from the next taxable period.
Presumed opt-out for insurance contracts between 1 June and 31 August 2026

The Royal Decree provides a presumption of opt-out in line with the prior legislation, unless the beneficiary explicitly requests withholding at the latest upon liquidation of the contract. Said explicit request must also be made in writing and at the latest upon liquidation of the contract.
Voluntary payments for realizations between 1 January and 31 May 2026

For capital gains realized between 1 January 2026 and 31 May 2026, the withholding tax obligation does not apply due to the delayed approval of the legislation. The Royal Decree specifies that taxpayers who wish to have voluntary withholding tax applied, need to request this in writing and unambiguously, by the deadline set forth by the broker and at the latest by 31 August 2026. This request also implies that the taxpayer can no longer opt out for the remainder of 2026 for that account or product.
Revoking a previous opt-out:

An opt-out that is validly made will apply to all capital gains relating to that account or contract for the relevant tax year. Revoking the opt-out is only possible once per tax year and must also be made unambiguously and in writing. It takes effect as from the following tax year.

B. Annual reporting form (‘fiche’)

The opt‑out is accompanied by reporting obligations for Belgian financial intermediaries, i.e. withholding agents (banks, brokers, insurance companies). Where an individual has opted out, the financial institution must file an annual form (‘fiche’) with the Belgian tax administration by 1 March of the following year (similar to the existing reporting requirements). For gains realized prior to 1 June 2026 no reporting is required. The Minister of Finance will determine the lay-out and details of the form, which will have to include at least the amount of capital gains, identification details, and account or contract number.

Exit tax: annual certification requirement for payment deferral

For emigrating taxpayers, an exit tax applies on all latent capital gains on the date of departure. However, the legislation also allows for a payment deferral of this exit tax, subject to certain conditions. If no gains are realized within 24 months of departure, the exit tax is definitively canceled.

In case of payment deferral, the tax code imposes an annual certification requirement related to this 24 month ‘monitoring’ period. The Royal Decree now specifies the formalities attached to this certification. Taxpayers who have been granted a deferral must:

submit the certificate to the Belgian tax administration, either electronically or on paper;
no later than the last day of the 14th and 26th month following the month of the date of departure

The Minister of Finance will draft the relevant tax form, it is unclear when this form will be available. At a minimum this form will have to include:

the taxpayer’s tax residence; and
confirmation that the relevant financial assets are still held by the taxpayer and have not been subject to a taxable transaction; or
if a taxable transaction has occurred, a list of the affected assets.

The first certificate (due at the end of the 14th month) covers the period of 12 months from the date of emigration. The second covers the period from month 13 to month 24.

Entry into force and retroactive effect

Both Royal Decree enters into force on 1 June 2026, but the provisions relating to the reporting obligations for intermediaries and the certification obligations in the context of the exit tax apply retroactively as from 16 April 2026.

How can KPMG help you?

Whilst the Royal Decrees provide for a certain amount of clarity, many details remain uncertain. We will continue to monitor upcoming news on the matter. In the meantime, if you require any advice or assistance with respect to any of the above, do not hesitate to reach out to your KPMG advisor in Belgium.