How is the 2026 sale of UK unlisted shares taxed in Belgium after a demerger? (Income year 2026 / assessment year 2027)
How is a 2026 UK unlisted share sale taxed in Belgium? Usually at 10% above the 31 Dec 2025 value, but valuation, demerger and treaty rules also matter.
For a Belgian resident selling a minority holding in a UK unlisted company in 2026, the standard Belgian regime can tax the gain at 10%, generally using the value at 31 December 2025 as the starting value for shares already held before 2026. A preceding share exchange or demerger can require that value to be allocated between the shares sold and the shares retained, while a capital reduction may create an additional qualification risk. The final treatment depends on the exact valuation and transaction documents.
The figures below are illustrative and rounded. They concern income year 2026 and assessment year 2027.
The Belgian capital gains rules from 2026
Since 1 January 2026, Belgium taxes certain capital gains realised by individuals on financial assets, including shares in foreign unlisted companies.
For assets already owned before 2026, gains accumulated up to 31 December 2025 are in principle protected through a snapshot mechanism: the asset's value at that date becomes the reference acquisition value when calculating a later gain.
The legislation distinguishes three main situations:
Internal gains can be taxed at 33%.
A substantial participation of at least 20% benefits from a separate regime, including a €1 million exemption and reduced progressive rates.
Other transactions normally fall under the standard regime of 10%, subject to an annual exemption.
For assessment year 2027, income year 2026, the basic annual exemption is €10,000.
Importantly, the 20% threshold is assessed per transferor. Holdings of a spouse or other relatives are not aggregated for this Belgian test.
The standard regime is found in article 90, paragraph 1, 9°, c) of the Income Tax Code. The separate rates apply without municipal surcharges.
A gain is considered realised when the asset leaves the taxpayer's estate in exchange for consideration. The date on which the purchase price is actually paid is not decisive.
The legislation was adopted by the Chamber on 3 April 2026, in the law of 6 April 2026, published in the Belgian Official Gazette on 21 April 2026. The administration subsequently commented on the regime in circular 2026/C/74 of 22 July 2026.
How is the 31 December 2025 value of unlisted shares determined?
For shares already held before 1 January 2026, the basic calculation is:
sale price − value at 31 December 2025 = capital gain or loss
This calculation is made on a gross basis. Transaction costs, advisers' fees and taxes are not deductible from the taxable gain.
Where the taxpayer's genuine historical acquisition value is higher than the 31 December 2025 value, that higher acquisition value may still be used for disposals made up to 31 December 2030.
For unlisted shares, the legislation provides several valuation methods. The relevant 31 December 2025 value can be based on the highest applicable value resulting from:
a price used in a transfer between independent parties, incorporation or capital increase during 2025;
a contract or put-option offer in force on 1 January 2026;
the statutory formula of equity + 4 × EBITDA for the last financial year closed before 1 January 2026;
a valuation report prepared, by way of derogation from that formula, by an independent réviseur d'entreprises or ITAA-certified accountant who is not the company's usual professional.
The professional valuation report must be established no later than 31 December 2027.
This possibility is particularly important for companies whose balance sheets do not reflect the economic value of their assets.
Why the statutory valuation formula can produce a very different result
Consider a privately held UK company with valuable real estate that has remained on its balance sheet at a very low historical cost.
A market-based valuation might put the group at around £20 million, while the statutory equity + 4 × EBITDA formula could produce a value of only around £1.7 million.
For a minority shareholder, that difference can completely change the tax outcome.
In the illustrative source case, the market-based allocation produced a starting value of roughly £0.7 million for the shares eventually sold. Using the statutory formula instead could have reduced that starting value to approximately £76,000.
The difference is potentially dramatic: the properly documented market valuation could result in little or no taxable gain, while reliance on the formula could result in Belgian tax approaching €69,000.
The lesson is not that one valuation method can simply be chosen for convenience. The correct value must satisfy the statutory requirements and be supported by appropriate evidence.
What should a professional valuation contain?
A qualifying report may rely on evidence such as:
a contemporaneous valuation of the company's assets at 31 December 2025;
offers received around the valuation date;
negotiations with an independent purchaser;
later transactions that corroborate the market value existing at 31 December 2025;
statutory accounts;
cash, debts and other liabilities;
recognised valuation methods used in the relevant sector.
Circular 2026/C/74 indicates that a report using valuation methods normally accepted in the sector should only be challenged in very exceptional circumstances.
An internal spreadsheet or valuation prepared by the company's regular advisers may therefore be valuable evidence, but it is not necessarily a substitute for the independent Belgian professional report required by the legislation.
What happens when only part of the business is sold?
A further difficulty arises where the company is reorganised before the sale.
Imagine that a shareholder initially owns shares representing the whole group. Before an external sale:
the existing shares are exchanged for shares in a holding company;
some assets are moved within the corporate group;
one part of the group is separated through a demerger;
the shareholder receives shares representing the separated business;
only those shares are sold, while the remainder of the investment is retained.
The full 31 December 2025 value cannot simply be allocated to the shares that are sold.
The snapshot value must instead be divided between the sold shares and the retained shares according to the real value represented by each part.
For example, if approximately 80% of the group's real value relates to the part eventually sold, approximately 80% of the shareholder's 31 December 2025 starting value should follow those shares. The remaining 20% stays attached to the shares that continue to be held.
Circular 2026/C/74 illustrates this principle with a split where an original acquisition value of €5,000 is allocated €3,000 / €2,000 between the resulting shareholdings.
A comparable proportional allocation has historically applied to partial demergers under article 45 of the Income Tax Code.
Is a share-for-share exchange itself taxable?
The new regime contains an exemption for certain gains realised when shares are contributed in exchange for newly issued shares.
Instead of taxing the gain immediately, the relevant acquisition value is preserved and transferred to the new shares.
Circular 2026/C/74 refers in this context to article 96/2, paragraph 1, 4° of the Income Tax Code.
Consequently, in a qualifying restructuring, a share-for-share contribution may be tax-neutral at shareholder level and the 31 December 2025 value can continue into the replacement shares.
The crucial question then becomes how that value is allocated if the new shares are subsequently split between different businesses.
The main risk: a demerger involving a capital reduction
Some UK reorganisations use a capital reduction demerger.
This type of operation does not map perfectly onto Belgian corporate-tax concepts, particularly because the United Kingdom is no longer an EU Member State and the neutrality rules of the EU merger directive do not automatically solve the issue.
The economic analysis may support treating the transaction as a split: the shareholder receives shares in another company, ownership proportions remain comparable and no economic value is actually distributed out of the group.
However, Belgian dividend rules create an additional question.
Belgian tax law can treat a reduction of capital as a dividend to the extent that the company has reserves, with the reduction allocated proportionally between paid-up capital and reserves.
This becomes especially relevant where shares have first been contributed to a holding company at a value considerably higher than their old historical acquisition cost and the holding company's capital is subsequently reduced.
One possible interpretation is that the operation remains a genuine split and the acquisition value is simply allocated between the resulting shares.
Another possible approach would be to analyse part of the capital reduction as a distribution, potentially taxable as a dividend at 30% rather than as a capital gain at 10%.
The interaction between this mechanism and the new 31 December 2025 snapshot, including the role of article 102, is particularly important because the 2026 legislation is still recent.
For a material transaction, the legal documentation of the demerger and capital reduction should therefore be reviewed separately rather than assuming that foreign tax neutrality automatically means Belgian neutrality.
Currency movements can create a Belgian gain even when there is a loss in pounds
Belgian taxpayers calculate their taxable result in euros.
That means the 31 December 2025 starting value and the later disposal proceeds may have to be converted using exchange rates from different dates.
The source analysis used the following ECB reference rates:
31 December 2025: GBP 0.87260 per euro, equivalent to approximately €1.1460 per pound;
a late-July 2026 disposal reference: GBP 0.85524 per euro, equivalent to approximately €1.1693 per pound.
The pound had therefore strengthened by around 2%.
As a result, a disposal that shows a modest loss when both amounts are compared in pounds can potentially become a small gain once each amount is translated into euros at the appropriate rate.
For illustration, a starting value around £0.7 million and disposal proceeds in the same broad range can move from a sterling loss to a euro gain of approximately €16,000, depending on the gross sale price used.
After the €10,000 annual exemption, a €16,000 gain would leave approximately €6,000 taxable at 10%, resulting in tax of only a few hundred euros.
The exact result depends on the actual gross consideration and the exchange rate on the legally relevant disposal date.
Why advisers' fees cannot simply be deducted from the sale price
Another important distinction is the difference between:
the shareholder's gross entitlement under the sale agreement; and
the net amount actually transferred after professional fees and transaction costs.
Under the Belgian rules described in the source analysis, costs are not deductible when calculating the capital gain.
A completion statement can therefore be decisive. It should ideally distinguish:
headline purchase price;
completion adjustments;
transaction expenses;
professional fees;
the shareholder's gross entitlement;
the final amount transferred.
If the difference between the contractual price and the amount ultimately received consists mainly of non-deductible costs, using only the net bank receipt could understate the Belgian disposal value.
Can a Belgian capital loss be carried forward?
Under the framework described for income year 2026, losses can offset gains of the same year and the same category.
They are not carried forward indefinitely.
Consequently, if the euro calculation ultimately produces a loss and there are no qualifying gains against which it can be used in that year, the loss may have no subsequent tax value.
Can the United Kingdom also tax the sale?
UK domestic law introduces another layer.
Since 6 April 2019, a non-UK resident can potentially be subject to UK capital gains tax on an indirect disposal where:
at least 75% of the company's gross asset value derives from UK land; and
the seller satisfies a 25% participation test.
For this UK test, certain connected persons, including close relatives, can be taken into account.
This is notably different from the Belgian 20% substantial-participation test, which is assessed individually.
Only the relevant increase in value since 6 April 2019 is generally within the UK non-resident regime, and a potentially applicable UK return can be due within 60 days of completion.
What does the Belgium-UK tax treaty say?
Domestic UK rules are not the end of the analysis.
Article 13 of the 1987 Belgium-United Kingdom double tax convention deals with capital gains.
Article 13(4) provides, in broad terms, that gains from property other than the specific categories covered by the preceding paragraphs are taxable only in the seller's state of residence.
The treaty does not contain a specific land-rich company clause assigning taxing rights over shares in a property-rich company to the country where the underlying real estate is located.
The 2009 protocol, in force since 24 December 2012, changed paragraph 3 of Article 13 concerning ships and aircraft rather than inserting such a land-rich-company provision.
The OECD Multilateral Instrument does not change that conclusion on the reasoning of the source analysis because the United Kingdom reserved the right not to apply the MLI's relevant capital-gains provision.
For a Belgian resident covered by the treaty, this can therefore result in Belgium retaining the exclusive taxing right over the share gain, notwithstanding the UK's domestic indirect-disposal legislation.
There are still important qualifications. A UK reorganisation clearance does not necessarily decide the treaty issue, and UK anti-avoidance provisions may require separate consideration.
Where a UK 60-day reporting period could apply, the treaty position should therefore be established before that deadline rather than only when preparing the later Belgian return.
What must be reported in Belgium for income year 2026?
A disposal realised during 2026 belongs to income year 2026 and is reported in the Belgian return for assessment year 2027.
For transactions carried out without a Belgian intermediary, there is no Belgian intermediary withholding the tax. The taxpayer must report the relevant transaction themselves.
The return may need to document:
the disposal;
the gross proceeds;
the 31 December 2025 starting value;
the allocation of that value following any restructuring;
the €10,000 exemption;
the professional valuation report;
the exchange rates used.
Belgian filing deadlines for the 2027 return are expected to be published in spring 2027.
The independent valuation report itself must be prepared no later than 31 December 2027.
Do dividends and foreign bank accounts follow the same rules?
No. They are separate issues.
Dividends received by a Belgian resident from a UK company can be taxable in Belgium as movable income at 30% and may need to be declared separately from the capital-gains transaction.
Foreign bank accounts are also subject to separate reporting obligations. A foreign account must generally be mentioned in the Belgian income-tax return, and its existence must be reported once to the Central Point of Contact of the National Bank of Belgium.
The transfer of sale proceeds from the United Kingdom to a Belgian bank account is not, by itself, a new taxable event. Nevertheless, supporting documents such as the sale agreement and completion statement should be retained to demonstrate the origin of the funds.
Registered foreign shares that are held directly in a company's shareholder register should also be distinguished from a foreign securities account. The shares themselves do not automatically create the same foreign-account reporting obligation.
What documents matter most?
For a cross-border demerger followed by a sale, the decisive evidence will normally include:
the independent 31 December 2025 valuation report;
underlying company accounts and valuation schedules;
documentation supporting the market value of major assets;
the sale and purchase agreement;
the final completion statement;
documents detailing the share-for-share exchange;
the demerger agreement;
documents relating to any capital reduction;
evidence of the economic allocation between the sold and retained businesses;
relevant ECB exchange rates;
any UK tax clearance;
documentation supporting the Belgium-UK treaty position.
In a transaction of this type, the valuation and legal qualification can matter far more than the amount ultimately appearing on the shareholder's bank statement.
Frequently asked questions
Is every gain on UK shares taxed at 10% in Belgium from 2026?
No. 10% is the standard regime, but different rules can apply to internal gains, substantial participations of at least 20%, abnormal transactions or transactions that are recharacterised in another way. The exact facts determine which regime applies.
Is the 31 December 2025 value automatically the purchase price for Belgian tax?
For financial assets already held before 2026, the 31 December 2025 snapshot is generally crucial. Unlisted shares nevertheless require a legally acceptable valuation method, and the historical acquisition value may be used instead where it is higher for sales up to 31 December 2030.
Can I deduct lawyers' and advisers' fees from a Belgian share gain?
Under the rules applied in the source analysis, transaction costs and advisers' fees are not deductible. The contractual gross consideration therefore matters, not only the net cash received after costs.
Does a UK demerger automatically qualify for Belgian tax neutrality?
No. Belgian treatment must be analysed under Belgian rules. A share exchange and subsequent split may be neutral, but a capital reduction demerger can raise a separate risk of dividend treatment.
Can exchange rates create a gain even if I lost money in pounds?
Yes. Belgium calculates the taxable result in euros. If the pound appreciates between the 31 December 2025 valuation date and the disposal date, a sterling loss can become a euro gain.
Is UK tax automatically due when the company mainly owns UK property?
Not necessarily. UK domestic law contains a 75% property-rich test, a 25% participation test and potentially a 60-day reporting deadline, but the Belgium-UK tax treaty can affect which country ultimately has the taxing right.
Sources
KPMG Belgium, the new tax on capital gains on financial assets: https://kpmg.com/be/fr/insights/my-tax-compass/corporate-tax-insights/la-nouvelle-taxe-sur-les-plus-values-des-actifs-financiers.html
Baker Tilly Belgium, impact on investors and entrepreneurs: https://bakertilly.be/fr/news/taxe-sur-les-plus-values-des-actifs-financiers-a-partir-de-2026-impact-sur-les-investisseurs/
Deg and Partners, who pays, on what, and from when: https://blog.degandpartners.com/fr/article/taxe-sur-les-plus-values-qui-paie-sur-quoi-et-a-partir-de-quand-/30781
Bazacle and Solon, the clarifications of circular 2026/C/74: https://www.bazacle-solon.eu/taxe-plus-values-belgique-circulaire-2026-c-74/
Circular 2026/C/74 of 22 July 2026 (Dutch version): https://blog.oeccbb.be/nl/article/circulaire-2026c74-over-de-belasting-op-meerwaarden-op-financiele-activa-in-de-personenbelasting/31950
Deg and Partners, valuation at 31 December 2025, four methods: https://blog.degandpartners.com/fr/article/valorisation-au-31-decembre-2025-quatre-methodes-un-enjeu-crucial/30785
Delsol Avocats, the new tax on capital gains in Belgium: https://www.delsolavocats.com/La-nouvelle-taxe-sur-les-plus-values-sur-actifs-financiers-en-Belgique
OECCBB, the valuation mission entrusted to réviseurs and certified accountants: https://blog.oeccbb.be/fr/article/taxe-sur-les-plus-values-sur-les-actifs-financiers-votee-ce-que-les-professionnels-du-chiffre-doivent-savoir-sur-la-mission-de-valorisation./30777
European Central Bank, euro foreign exchange reference rates of 31 December 2025: https://www.ecb.europa.eu/stats/exchange/eurofxref/shared/pdf/2025/12/20251231.pdf
Tiberghien, contribution of shares and rollover of the acquisition value: https://tiberghien.com/nl/4466/meerwaardebelasting-bij-verdeling-na-schenking-echtscheiding-of-overlijden
Moore Law, what we know about the new capital gains tax: https://www.moorelaw.be/nl/nieuws/nieuwe-meerwaardebelasting-wat-weten-we-al
Circular 2026/C/74 of 22 July 2026 (French version, split example): https://blog.forumforthefuture.be/fr/article/circulaire-2026c74-concernant-limpot-sur-les-plus-values-sur-les-actifs-financiers-a-limpot-des-personnes-physiques/31949
Coppens, accounting and tax treatment of partial demergers (article 45): https://www.coppensfiscaliste.be/traitement-comptable-et-fiscal-des-scissions-partielles/
European Central Bank, pound sterling reference rates, last four months: https://www.ecb.europa.eu/stats/policy_and_exchange_rates/euro_reference_exchange_rates/html/eurofxref-graph-gbp.en.html
GOV.UK, capital gains tax for non-residents, indirect disposals: https://gov.uk/capital-gains-tax-for-non-residents-uk-residential-property
GOV.UK, helpsheet HS307 (2026), non-resident capital gains on direct and indirect disposals: https://www.gov.uk/government/publications/non-resident-capital-gains-for-land-and-property-in-the-uk-self-assessment-helpsheet-hs307/hs307-non-resident-capital-gains-on-direct-and-indirect-disposals-of-interest-in-uk-land-and-property-2026
UK-Belgium double taxation convention of 1 June 1987 (article 13): https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/496634/belgium-dtc_-_in_force.pdf
Protocol of 24 June 2009 amending the UK-Belgium convention: https://assets.publishing.service.gov.uk/media/5a7a16dae5274a34770e42da/TS.4.2013.ProtBelgiumDoubleTax.pdf
MLI article 9 (capital gains from land-rich entities) and the UK reservation: https://www.action15-mli.net/multilateral-convention/article-9-capital-gains/article-9-capital-gains-from-alienation-of-shares.html
Wikifin, declaring your foreign accounts: https://www.wikifin.be/fr/impots-emploi-et-revenus/declaration-dimpots/vos-revenus-mobiliers/declarer-vos-comptes-letranger
This article presents a general tax framework for income year 2026 / assessment year 2027 and does not constitute a personalised tax opinion. Tax rules can change from year to year, and the correct treatment depends on the precise shareholding, valuation, restructuring documents, sale terms, tax residence and other individual circumstances.
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