A British citizen who lives in France can sell shares held with a UK broker and still face a French tax filing, even when the UK has charged no Capital Gains Tax. The decisive questions are usually where you are tax-resident on the disposal date, what was sold, how the gain was calculated in euros and whether the holding falls within a treaty exception. Ordinary London-listed shares, an Individual Savings Account (ISA), dividends, a French plan d’épargne en actions (PEA) and shares in a property-rich company do not receive the same treatment. Brexit did not turn a UK brokerage account into a French tax shelter, nor did it create a general UK tax exemption that removes the French declaration. This guide focuses on private investors who are resident in France and sell ordinary UK shares after Brexit. It explains the French plus-value—capital gain—calculation, the France–UK double-tax treaty, the forms and evidence required, the foreign-account reporting issue and the procedure for correcting an incorrect assessment. It does not cover the purchase of French property, company creation or a professional trading business. Those cases require a separate analysis of residence, business activity, valuation and treaty provisions.

I. Are UK shares taxed in France after Brexit and where does the treaty put the gain?

A. How is a capital gain on ordinary UK shares calculated and taxed in France?

The starting point is the disposal, not the country in which the broker is established. A sale of shares in a United Kingdom company by a person whose tax residence is in France is normally examined under French rules for investment income and capital gains. The French expression plus-value mobilière means a gain on the sale of movable financial property, such as shares or securities. The taxable event is generally the transfer or disposal of the securities, rather than the later transfer of the cash to a French bank account. Moving the proceeds from a UK platform to France does not create a second gain, but it also does not erase the first one.

Article 150-0 A of the French General Tax Code is the central domestic provision for private disposals of securities. It brings the relevant net gains into income tax; the operative text states that such gains “sont soumis à l’impôt sur le revenu”. The rule is not limited to French companies. It covers securities held directly, through an intermediary or in other legally defined forms. The fact that the share certificate, platform or company is British therefore does not prevent France from applying its domestic calculation where the taxpayer is French-resident.

The arithmetic is more demanding than a UK platform summary suggests. Article 150-0 D of the General Tax Code defines the net gain by reference to the effective disposal price, reduced by relevant costs, and the effective acquisition price. The provision refers to the “prix effectif de cession des titres ou droits”. In a British portfolio, both sides of that calculation may have been recorded in pounds sterling while the French return requires a defensible euro amount. Keep the transaction confirmation, the acquisition statement, the broker’s fee, the date of settlement, the exchange-rate source and the resulting euro calculation. A gain calculated only from the difference between two sterling balances can be wrong when contributions, dividends, transfers or currency movements have occurred in the meantime.

Build the calculation holding by holding. Identify the security, the number of shares, each acquisition lot, the date and cost, later corporate actions, the disposal date, sale proceeds and fees. Check whether a stock split, consolidation, merger, takeover, dividend reinvestment or transfer from an employee plan changed the acquisition history. A transfer between two accounts may be neutral if beneficial ownership has not changed, but a sale followed by a repurchase is a disposal and a new acquisition. A cash withdrawal is not the same as a share disposal. A broker’s annual tax certificate is valuable evidence, but it may have been prepared using UK pooling or tax-year conventions rather than the French calculation required for a French resident.

Currency conversion deserves a separate schedule. For each disposal, state the sterling proceeds, the sterling cost, the chosen conversion method, the relevant dates and the euro result. Do not use the exchange rate on the day you moved the proceeds if the legal disposal occurred earlier. Do not use the net proceeds after a UK withholding or platform charge where French law requires the gross disposal price and a separately identified deductible cost. If the broker reports only a global portfolio gain, request transaction-level data. The more substantial the gain, the more difficult it becomes to defend a single unexplained conversion figure.

Once the gain has been calculated, the income-tax regime must be identified. For a person fiscally domiciled in France, Article 200 A of the General Tax Code places the relevant gains within the flat-rate framework and fixes the income-tax rate in the current text at “12,8 %”. That is the income-tax component. Social levies may also apply, with the applicable rate and any exemption depending on the tax year and the taxpayer’s circumstances. A headline calculation that simply multiplies the sterling profit by 30 per cent can therefore conceal the wrong residence, the wrong year, the wrong base or a missing social-levy analysis.

The taxpayer can sometimes elect for the progressive income-tax scale instead of the flat-rate treatment. The French term barème progressif means the progressive income-tax scale. The election is global for the income and gains within its statutory scope; it is not a switch that can be made only for the one UK share that produced the largest profit. The official French explanation of share disposals describes the annual option and the interaction with available holding-period allowances. A pre-2018 acquisition can require a different analysis from a share bought after 1 January 2018. Do not select the option because it produces a lower result in one isolated spreadsheet without testing dividends, interest and other securities in the same household.

Losses matter as well. The French term moins-value means a capital loss. The official guidance explains that losses of the same nature are first set against gains of the year and can, subject to the statutory conditions, be carried forward for later years. A UK broker may show a loss in pounds that cannot simply be imported into the French return without checking the euro calculation and the French reporting period. Preserve the original transaction data for both profitable and loss-making disposals. Omitting losses may overstate the French tax; claiming a loss already used in the UK or in an earlier French return may create a different problem.

Shares inside a UK ISA need a separate warning. An ISA, or Individual Savings Account, is a UK tax wrapper. Its UK label does not automatically make every gain invisible to France. France must analyse the underlying disposal under its own law, together with the taxpayer’s residence and the treaty. The British Desk’s separate guide to UK ISAs held by French residents addresses that issue in detail. Do not combine an ISA gain with a normal taxable brokerage account in one unexplained total, and do not assume that a UK provider’s “tax-free” description is a French exemption.

Dividends are not capital gains. A dividend is a distribution of company profit; a capital gain arises from a disposal of the shares. The France–UK treaty uses different articles for those categories, and the forms may require different entries. The Desk’s guide to UK dividends and REIT withholding should be used for a distribution or a refund claim. A statement showing “total return” can mix dividends, reinvested dividends and changes in market value. Separate them before calculating the French gain.

B. Does the France–UK tax treaty decide where ordinary UK shares are taxed?

The current France–UK double-tax convention was signed in 2008 and entered into force after the transition period. Its capital-gains article is Article 14, not the pension or dividend article. The French text is published in the Légifrance decree publishing the convention. The treaty’s residual rule states that gains from property outside the specific exceptions “ne sont imposables que dans l’État contractant dont le cédant est un résident”. For a person treaty-resident in France selling ordinary UK shares, that usually points to France, subject to the exceptions below and to the domestic laws of both countries.

Article 14 first deals with immovable property. It then covers shares that are not regularly traded on an approved stock exchange when their value, directly or indirectly, derives principally from immovable property situated in a contracting state. It also covers certain interests in partnerships or trusts whose assets are principally property or property-rich rights. In practical terms, a British resident in France who sells ordinary shares quoted on the London Stock Exchange is in a different treaty position from someone who sells a private shareholding in a company whose principal asset is a French or British building. A shareholding in a property-rich entity can therefore engage the source state’s taxing right even when the seller lives elsewhere.

The exclusion for shares regularly traded on an approved exchange is important, but it is not a universal answer. Check the exact instrument, the listing, the trading status and the source of the value. An exchange-traded company whose business is property investment may still require a careful Article 14 analysis; a private company may fall within the property-rich rule even when the owner describes the holding simply as “shares”. A trust, partnership, employee share arrangement or investment fund can also have its own classification. If the company owns a French property, do not rely on the broker’s ticker alone. Obtain the company’s accounts, the asset composition and the nature of the rights sold.

Article 14 also contains a former-resident safeguard. It preserves a contracting state’s right, under its own law, to tax certain gains on a person who was resident there during the previous six fiscal years or was resident there during the year of disposal. This wording does not mean that the United Kingdom automatically taxes every share sale by a new French resident. UK domestic law still determines whether a charge exists. The GOV.UK guidance for people living abroad says that a non-resident generally does not pay UK Capital Gains Tax on assets such as ordinary UK shares, while warning that the relevant double-tax agreement and residence history must be checked. Temporary non-residence, a return to the UK, a disposal of UK land or a property-rich company can change the result.

The treaty does not turn a French tax return into an optional document. If Article 14 gives France the taxing right, the gain must be calculated and declared under French law. If the treaty gives the United Kingdom a taxing right in an exception, the gain still needs to be disclosed so that the relief mechanism can be applied correctly. Article 24 of the convention governs the elimination of double taxation. It does not create a credit for a UK amount that was merely withheld, later refunded or never legally due. Obtain the final UK assessment or the provider’s legal explanation before claiming a credit in France.

Residence has to be fixed for the disposal year. A move from the UK to France, a return trip, a second home, a continuing UK employment or family ties can produce a domestic-residence disagreement before the treaty tie-breaker is even reached. A person can also be resident under both countries’ domestic rules while being treaty-resident in only one. Prepare a day-by-day chronology, identify the permanent homes, record the family and economic links and retain the residence certificates. The treaty residence conclusion should match the tax year in which the shares were actually sold, not simply the date on which the proceeds reached a French account.

A useful boundary case is CAA de Versailles, 1st chamber, 20VE01265, 19 October 2021. It concerned a non-resident disposing of rights in a French company and examined the domestic 25 per cent participation threshold alongside Article 14 of the France–UK convention. The court described the domestic rule as applying where the seller held more than 25 per cent of the rights in the profits of the relevant company, subject to the treaty. That is not a ruling that taxes an ordinary small holding of UK-listed shares in France; it is a reminder that a large private participation, a French company or a property-rich structure must be screened before the simple “resident country” rule is used.

Another boundary concerns an old share exchange or a gain placed in a French deferral before the taxpayer moved. The Conseil d’État, 8th–3rd chambers, no. 360352, 19 July 2016, examined a deferred gain involving a former UK resident under the earlier France–UK convention. The court held that the fact that the later disposal was taxable in another country did not, by itself, remove the original state’s power to tax the deferred gain when the deferral ended. The case is not a shortcut for a modern ordinary-share sale; it signals that a historic exchange, contribution or departure tax must be traced separately from a normal purchase and sale.

Finally, do not confuse capital gains with a UK pension, savings interest or dividend. The treaty article, the taxable base and the reporting boxes change. The British Desk’s existing articles on UK savings interest, pensions and property tax provide internal context, but the present analysis is limited to ordinary share disposals and the evidence needed to defend their treatment.

II. How should a British resident declare UK shares in France and challenge an incorrect tax bill?

A. Which forms, calculations and documents should I use for a UK share sale?

Start with a classification sheet before opening the French online return. Put each item into one of five lines: ordinary shares in a taxable investment account; shares in an ISA or another UK wrapper; shares in a PEA or French wrapper; a dividend or distribution; and a shareholding that may be property-rich, private, trust-based or connected with employment. Then record the French and UK residence position on the disposal date. This prevents the common error of attaching a UK broker’s “capital gains” total to every payment shown on the account.

Article 170 of the General Tax Code requires a detailed income declaration. The text refers to “une déclaration détaillée de ses revenus et bénéfices”. A foreign payment is not omitted because the broker is overseas, because the gain is treaty-protected or because the UK tax result is nil. Put the gain in the French return under the appropriate category, attach the relevant supplementary form and add an explanatory note where a foreign account, ISA, treaty exception or currency calculation will not be obvious to the tax office.

The official Form 2074 page explains that the form is used for gains and losses on disposals of securities and related transactions. Depending on the number and type of operations, a French resident may use the 2042-C return, a 2074 declaration, a 2074-CMV for certain consolidated gains and losses, or another annex identified by the current notice. The correct form depends on the tax year, the broker’s calculation and the operation. Do not copy a 2025 box number into a 2026 return without checking the current form and notice.

The 2074 decision tree is practical. If the financial institution has calculated every relevant gain and loss and the transaction pattern falls within the simplified route, the French instructions may permit a direct entry. If the institution has not calculated all the operations, if several categories are mixed, if an old holding-period allowance is claimed or if a special event occurred, a detailed 2074 calculation may be required. A UK broker’s annual statement is not a French form. Reconcile its figures rather than assuming it answers every French field.

For each disposal, keep the following file:

• the acquisition contract, trade confirmation and original cost in pounds sterling;
• the disposal confirmation, sale price, settlement date and fees;
• the exchange-rate evidence and a calculation showing the euro acquisition and disposal values;
• records of splits, mergers, takeovers, transfers, reinvested dividends and earlier disposals;
• the broker’s annual tax statement and the underlying transaction export;
• the ISA, employee-plan, trust or fund rules where a wrapper or special vehicle is involved; and
• the French return, supplementary schedules, acknowledgement, assessment and any UK tax certificate.

The broker account may create a second reporting obligation. Article 1649 A of the General Tax Code requires French residents to declare the references of certain accounts opened, held, used or closed abroad. The provision refers to “les références des comptes ouverts, détenus, utilisés ou clos à l’étranger”. The detailed regulatory rule concerns accounts held with an institution that habitually receives securities or funds. A foreign share register and a foreign brokerage account are not necessarily the same thing, so identify the account holder, the custodian, the account number, the opening and closing dates and the relevant Form 3916 or 3916-bis instructions. Keep the account-reporting analysis distinct from the calculation of the gain.

Online filing is the normal route. Article 1649 quater B quinquies sets the electronic-filing framework for the income declaration and its annexes, while allowing the statutory alternatives where the taxpayer cannot file electronically. If the online service does not provide a suitable explanation box, submit the return with the legally correct entries and send a dated message with the calculation, the treaty article and the documents that cannot be uploaded. Save the submission receipt. A telephone conversation without a written trace is a weak foundation for a later challenge.

Check the UK side separately. HMRC’s share-sale guidance explains that UK Capital Gains Tax may arise on a profit from disposing of shares and that shares in an ISA receive UK treatment distinct from ordinary shares. For a person living abroad, the UK guidance on double taxation and residence may say that ordinary UK shares are not normally taxed in the UK, but the temporary-non-residence and property-related rules can matter. If UK tax was paid, obtain the final computation and establish whether it is a tax covered by Article 24 of the convention. Do not claim a French credit for a UK amount that was only an interim deduction.

For a simple illustration, suppose a French resident bought 1,000 shares for £8,000, paid £100 of acquisition costs, sold them for £15,000 and paid £120 of disposal costs. The French calculation cannot be stated accurately until the acquisition and disposal amounts are converted under a defensible method for the relevant dates. The gross sterling difference of £7,000 is not automatically the taxable euro gain. The file must also check whether some shares came from a dividend reinvestment, whether earlier losses are available, whether the holding was in an ISA and whether the treaty contains a source-state exception. A numerical example is a control tool, not a filing result.

Before submitting, run a five-question check: did a disposal occur; is France the taxing state under the treaty; is the asset an ordinary share rather than a dividend, property-rich right or wrapper product; is the euro calculation reproducible; and has the foreign account been reported where required? If any answer is uncertain, do not hide the uncertainty in a global broker total. Explain the issue and preserve the evidence that supports the chosen treatment.

B. How can I correct a French assessment, recover tax or invoke the treaty?

The remedy depends on the error. A missing annex before the assessment may be corrected through the online service or a written submission. A wrong exchange rate, an omitted loss, a mistaken ISA classification, a duplicate dividend or a failure to apply Article 14 requires a reasoned correction with a revised calculation. A réclamation contentieuse is a formal tax claim seeking a reduction or refund; it is more precise than an informal request for general guidance. The claim should identify the year, the assessment or payment reference, the securities, the disputed amount, the legal basis and the requested result.

Article L190 of the Book of Tax Procedures defines the contentieux route for claims seeking correction of an assessment or recognition of a right. It refers to “la réparation d’erreurs commises dans l’assiette ou le calcul des impositions”. That wording is useful for a share-sale dispute: the argument can concern the tax base, the category, the treaty allocation, the calculation of the gain, an available loss or the amount of a credit. State the precise error rather than simply saying that the tax bill is too high.

Timing is critical. The current Article R*196-1 of the Book of Tax Procedures sets the ordinary framework for claims relating to income tax and other taxes. It uses the formula “au plus tard le 31 décembre de la deuxième année suivant celle”, with the starting event depending on the type of tax, assessment or payment. A separate rule can apply to withholding, direct-local taxes or a new assessment correcting a previous notice. File as soon as the error is identified, even if a deadline appears distant. Attach proof of submission and retain the complete file exactly as sent.

When the tax office issues a proposition de rectification—a proposed correction—answer the stated reason within the letter’s time limit. If the authority says that the shares were property-rich, provide the company’s asset evidence and the listing information. If it says that the broker’s cost basis is unreliable, provide the acquisition contracts and the currency schedule. If it says that the United Kingdom can tax the gain, address Article 14 and the domestic UK charge separately. If it rejects a credit, show the UK assessment, the treaty provision and whether the tax was final and economically borne.

Do not assume that a missed pre-assessment reply ends every remedy. The procedure, burden of proof and available arguments depend on the notice and the assessment route. A response that was sent to the wrong tax office, a claim based on an obsolete form or a submission that failed to identify the disposal can create avoidable objections. The taxpayer should preserve the envelope or electronic notification, the date of receipt, the response deadline, the address used, the acknowledgement and every attachment. These procedural facts can matter as much as the calculation.

A treaty disagreement can require more than a domestic claim. Article 26 of the France–UK convention provides a mutual agreement procedure for a resident who considers that the actions of one or both states produce taxation contrary to the convention. The request is made to the competent authority, normally starting with the state of residence, within the treaty’s stated period. It does not replace a domestic objection where the French deadline is running. Use the domestic claim to protect the French position while examining whether the UK authority must be approached separately. The same official convention text contains the procedure and the double-tax provisions.

For ordinary UK-listed shares, a double-tax claim may be unnecessary because the United Kingdom has not charged Capital Gains Tax on the disposal. If both states nevertheless tax the gain, identify why. The reason may be a former-resident rule, a temporary absence, a property-rich company, an employee share plan, a deferred gain or a residence disagreement. A credit is limited by the treaty and the final tax actually due. The French calculation should not be reduced by an amount that HMRC later refunds, and the UK claim should not describe a French social levy as if it were automatically UK income tax.

The case law is useful mainly for locating the boundary. In CAA de Versailles no. 20VE01265, the court considered the interaction between a domestic participation threshold and Article 14 for a non-resident seller of rights in a French company. That fact pattern is materially different from a British resident selling a modest listed UK portfolio. In Conseil d’État no. 360352, the court dealt with a historic deferred exchange under the former convention. Neither decision authorises the administration to bypass the current treaty for every UK share sale. Both show why the share type, residence history, deferred-gain history and source-state exception must be stated precisely.

A practical claim should contain a short chronology and a reconciliation table:

1. the taxpayer’s residence and treaty position on the disposal date;
2. the identity, listing and asset profile of the company;
3. the acquisition and disposal lots, fees, exchange rates and euro calculation;
4. the French forms and boxes used, including any foreign-account declaration;
5. the UK return, assessment or confirmation that no UK charge arose;
6. the tax office’s stated ground for correction; and
7. the exact reduction, refund, credit or cancellation requested.

Attach the official broker documents and translate the material technical terms where needed. “Cost basis”, “bed and breakfasting”, “tax-free ISA”, “market value”, “beneficial ownership” and “property-rich company” do not have identical legal effects in French and UK practice. A brief English-to-French glossary can prevent the tax office from treating a platform label as a legal classification. Where the dispute involves a substantial participation, trust, employee shares, a return to the UK or a deferred gain, obtain a tailored review before signing a position that may be difficult to reverse.

The commercial result of this process is simple: a UK broker statement is an input, not the French return. The defensible file shows why the gain is taxable in France, why the treaty does or does not allocate a right to the United Kingdom, how the euro amount was calculated and which form carries the number. If the administration has already taxed the wrong asset or the wrong amount, the same file becomes the basis for a timely correction claim.

Conclusion

For a British resident of France, selling ordinary UK shares after Brexit will usually require a French capital-gains analysis even when the UK result is nil. The decisive steps are to establish treaty residence for the disposal year, identify the asset, calculate the gain in euros, separate capital gains from dividends and wrappers, report a foreign brokerage account where required and use the current French forms. Article 14 of the France–UK convention generally points ordinary share gains to the state of residence, but property-rich shares, private participations, former-resident rules, employee arrangements and deferred gains can change the answer.

If a French assessment is wrong, respond to the precise error with the transaction records, exchange-rate schedule, broker evidence, treaty analysis and revised calculation. Use the statutory claim route before the applicable deadline and coordinate any UK request so that a refund or credit is not claimed twice. A short, documented share-by-share reconciliation is often more persuasive than a global platform statement or a general assertion that the shares are British. The taxpayer’s residence, the treaty category and the proof of the calculation should lead the file from the first return through any appeal.