If you are a British citizen dealing with a French estate after Brexit and the inheritance-tax declaration was not filed on time, the important question is not simply how much tax is due. You must establish which deadline applied, which assets had to be reported, whether the France–United Kingdom inheritance-tax convention changes the calculation, and whether the delay resulted from an incomplete estate, a valuation problem, a notary’s omission or a genuine inability to pay. French inheritance tax is commonly referred to as droits de succession, meaning the tax charged on assets received on death. The filing itself is the déclaration de succession, the formal inventory and tax return sent to the French tax authority. A late filing can produce monthly interest and a surcharge, but the calculation is not always the same for a death in France, a death in the United Kingdom, a property whose title was not registered, or a return filed after a formal notice. A UK heir should therefore preserve proof of the date of death, the place of death, every exchange with the notary and the French tax office, and the date on which each asset became sufficiently known to value. This article sets out a practical route: identify the legal clock, file or correct the return without conceding an incorrect tax position, then challenge the interest or surcharge with evidence and the correct remedy.

I. What deadline applies to a UK heir and what must be filed?

A. How the six-month, twelve-month and twenty-four-month clocks operate

Brexit did not create a separate French inheritance-tax deadline for British nationals. The first question is where the deceased died, not the nationality of the heir. Article 641 of the French Code général des impôts (CGI), the General Tax Code, gives the basic rule. It states: De six mois, à compter du jour du décès, lorsque celui dont on recueille la succession est décédé en France métropolitaine; and then provides for one year in all other cases. The official wording is available in the current version of CGI Article 641. Thus, where a French-resident parent dies in Lyon, the normal filing deadline is six months from the date of death. Where a British-domiciled parent dies in England, the general French period is one year, even if the estate includes a house in France. The fact that the heir receives the papers late does not automatically move the statutory starting point.

The date must be calculated carefully. The death certificate, rather than the date on which probate is granted in England or the date on which the French notaire first contacts the family, normally supplies the starting event. A will dispute, a missing bank statement or a delay in obtaining a valuation may explain why the return was late, but it does not by itself suspend the tax clock. That explanation can still be highly relevant when asking the administration to reduce a surcharge or when bringing a professional-negligence claim against a notary.

There is a special extension for some French immovable property. Under CGI Article 641 bis, the Article 641 periods are extended to twenty-four months for a declaration containing immovables or real-estate rights where the deceased’s title had not been established before death by a properly transcribed or published deed, provided that the relevant notarial certificates are published within the same period. The text refers to vingt-quatre mois. This is not a general two-year period for every difficult succession. It is tied to a defined land-registration problem and to publication of the required notarial certificate. A British heir should ask the notary to identify the exact property, the title defect and the publication date in writing before relying on the extension.

Finally, the filing obligation and the tax liability are separate questions. Article 800 CGI says: Les héritiers, légataires ou donataires, leurs tuteurs ou curateurs, sont tenus de souscrire une déclaration détaillée. The official Article 800 text exempts direct-line heirs, the surviving spouse and the civil-partnership partner where the gross estate is below €50,000, subject to the condition concerning earlier unreported gifts. For other recipients, the threshold is €3,000. A British child inheriting a French bank account and a share in a house must not assume that the absence of tax after allowances removes the need to file. The value of the gross estate, earlier gifts and the relationship to the deceased must all be tested.

For a return that is already late, make a dated timetable before calculating anything:

• date and country of death;
• the ordinary six-month or one-year deadline under Article 641;
• any documented Article 641 bis title-registration issue;
• the date on which the return was actually lodged, or the date of an incomplete return;
• the date of any mise en demeure, meaning a formal notice to file;
• the date and amount of each payment or deposit; and
• the date on which the French tax office issued a notice, assessment or request for information.

This chronology often changes the result more than an argument based only on the heir’s nationality. It also reveals whether the administration has treated a filing as a complete declaration, a provisional declaration, a correction or no filing at all.

B. Which assets, forms and France–UK rules must be addressed?

French territoriality is governed first by domestic law and then, where applicable, by the treaty. CGI Article 750 ter can bring French-situs assets into the charge when the deceased was not fiscally resident in France. It also contains rules for worldwide assets where the deceased was fiscally resident in France, and for worldwide assets received by an heir who was fiscally resident in France for at least six of the ten years before receiving the inheritance. The French phrase domicile fiscal means tax residence. It is not determined merely by a French address on a notarial document or by holding a French residence permit.

In practical terms, a British heir should map the estate asset by asset. A house or apartment physically located in France is the obvious French connection. French bank accounts, shares in some French companies and rights linked to French real estate may also matter. UK bank accounts, pensions, investments, trusts and insurance policies must not be ignored merely because they are held in pounds or administered in the United Kingdom. Their treatment depends on the deceased’s tax residence, the heir’s residence, the legal nature of the asset and the treaty allocation. The French tax authority’s international guidance confirms the separate six-month and twelve-month filing periods, identifies the forms used for a succession and explains the route for a death abroad.

The usual French paperwork includes form 2705-SD, and, where relevant, form 2705-S, form 2705-A and the supporting schedules. The official forms and notices are available through the French tax authority’s inheritance-declaration page. The correct destination for a non-resident case can differ from the local tax office handling a French resident’s return. The non-resident service should be identified from the current official instructions, not from an old letter or a private checklist. At the time of writing, the international guidance identifies the Recette des Non-Résidents in Noisy-le-Grand and gives an email and telephone route. Keep proof of dispatch, the complete attachment list and any acknowledgement of receipt.

A late UK heir should prepare one coherent evidence pack. It should normally include the death certificate, the will and any codicil, the certificate of inheritance or equivalent notarial documents, identity and family-status records, the asset schedule at the date of death, account statements, property valuations, outstanding debts, mortgage statements, insurance documents, UK probate papers and evidence of exchange rates used. If a trust, life policy or pension is involved, obtain the governing policy or scheme documents rather than describing the asset by its everyday name. “Pension” and “insurance” are not tax classifications in themselves. For the payment mechanics that often arise once the figures are known, compare this desk’s related guide on paying French inheritance tax in instalments as a UK heir; that page is a supporting pillar, while this article focuses on the late-declaration and correction stage.

The relevant treaty is not the ordinary income-tax convention. France and the United Kingdom have a specific estate and inheritance-tax convention signed on 21 June 1963, published through the official Légifrance treaty record. Its operation must be tested against the asset, the deceased’s domicile for treaty purposes and the tax charged by each country. Brexit did not repeal that convention. It may allocate taxing rights or require relief where both states charge tax on the same property, but it does not turn every UK asset into a French-exempt asset and it does not remove the French filing duty.

On the UK side, HM Revenue & Customs explains the interaction in its Inheritance Tax Manual guidance on the France convention. Where French succession duty has been paid on property for which UK inheritance tax is also relevant, the available credit is subject to the treaty’s conditions and limits. HMRC also publishes general guidance on inheritance-tax double-taxation relief. The UK inheritance-tax return and the French declaration are separate filings. A UK grant of probate, a UK tax account or a claim for foreign tax credit is not a substitute for the French declaration.

Do not confuse the 1963 estate convention with the current France–UK income-tax convention. The latter can help determine residence for income such as pensions or rent, but the death-transfer analysis has its own treaty. If a British heir is also living in France, the six-out-of-ten-years rule in Article 750 ter may interact with treaty questions. That is precisely why a short factual memorandum should identify the deceased’s residence, the heir’s residence during the relevant years, the domicile concepts used in the UK file and each asset’s location before the tax figures are finalised.

A useful filing table for a UK family is the following:

Question	Evidence to obtain	Why it matters
Where did the deceased die?	Death certificate and place of death	It normally determines the six-month or one-year Article 641 period.
Was a French property title incomplete?	Notarial title search and publication certificate	It may support the limited twenty-four-month Article 641 bis period.
Where was the deceased fiscally resident?	Addresses, tax returns and treaty-residence evidence	It affects the scope of Article 750 ter and treaty analysis.
Where did the heir live?	French and UK residence history for the relevant ten years	It may affect the worldwide-assets rule for a French-resident heir.
What has already been filed?	Stamped forms, online receipts and notary correspondence	It distinguishes a late filing from a missing, incomplete or corrective filing.

II. The declaration is late: what can a UK heir pay, challenge and correct?

A. How French interest and surcharges are calculated after the deadline

The first financial layer is late-payment interest, known in French tax law as intérêt de retard. CGI Article 1727 provides that an unpaid tax claim due after the legal period attracts interest and states: Le taux de l’intérêt de retard est de 0,20 % par mois. The statutory calculation is applied to the relevant tax claim and runs according to the Code’s calculation rules. It is not a flat penalty for being British, for living in the UK or for using a solicitor. A payment already made can reduce the amount on which a later calculation runs, but the dates and allocation of that payment must be proven.

The second layer is a surcharge for a late or missing declaration. The current CGI Article 1728, in force from 21 February 2026, states that late production generally attracts a 10% surcharge where there is no formal notice or the declaration is filed within thirty days after receiving one, and 40% where it is not filed within that period. For declarations covered by Article 800, paragraph 2 provides a specific timing rule: the 10% surcharge begins on the first day of the seventh month after the expiry of the six-month and twenty-four-month periods, while 40% applies where the declaration is not filed within ninety days after a formal notice. The statutory text says: La majoration de 40 % s’applique lorsque cette déclaration n’a pas été déposée dans les quatre-vingt-dix jours following the formal notice.

The distinction matters. A formal notice should never be left in a pile of correspondence. Record the date it was received, preserve the envelope or electronic delivery record and calculate the ninety-day response period. A British heir who sends a detailed declaration before the period expires may be in a materially better position than an heir who waits for every family dispute to end. Conversely, a letter saying that the family is “working on the file” may not be a declaration and may not stop the statutory consequences.

The official summary on Service-Public’s inheritance-declaration page describes the practical regime as monthly interest and a 10% to 80% surcharge, with the 10% level ordinarily beginning after the applicable grace period. Because the wording and transitional rules have changed, a calculation should identify both the version of Article 1728 applicable to the filing and the date used by the tax office. For a death outside metropolitan France, Article 641 sets a one-year filing period, while current Article 1728 paragraph 2 expressly names the six-month and twenty-four-month periods. That interaction must be checked against the assessment rather than copied from a French-death example. Ask the non-resident service to state its calculation in writing if the notice appears to start the surcharge too early.

Do not turn a late return into an allegation of fraud without evidence. CGI Article 1729 concerns inaccuracies and omissions affecting assessment and provides 40% for a deliberate failure, and 80% for abuse of law or fraudulent manoeuvres in the circumstances defined by the text. It begins: Les inexactitudes ou les omissions relevées dans une déclaration. A missing valuation document caused by a cross-border delay is not automatically a deliberate omission. The taxpayer should separate an unknown or disputed item, an honest valuation range and an intentionally concealed asset. The response should correct the first two and contest any unsupported characterisation of the third.

Consider a simple illustration. Assume the French tax calculated on the late-filed return is €40,000 and the eligible delay produces twelve months of Article 1727 interest. At 0.20% per month, a rough interest figure before checking the statutory start and end dates is €960. A 10% surcharge would be €4,000 if its legal conditions are met. That is not a final assessment: deductions, payments, the date the tax became payable, the type of return and the exact version of the Code can change the result. The illustration shows why a family should challenge an incorrect start date even when it accepts that some interest is due.

Payment and liability should also be kept separate. CGI Article 1701 states that death-transfer duties are paid before the relevant registration or land-publicity formality and provides: Nul ne peut en atténuer ni différer le paiement sous le prétexte de contestation, subject to seeking restitution where appropriate. This means that a dispute about the tax base does not, by itself, authorise the heir to leave the whole account unpaid. The French tax authority explains that deferred or instalment arrangements may be available in defined circumstances in its guidance on how to pay inheritance tax. The application should be made with the declaration, supported by the estate’s liquidity position and any required security.

A provisional filing can be a protective step when the family knows the principal assets but cannot finish a valuation or locate every statement. It should not be a bare note. It should identify the deceased, heirs, known assets, liabilities, valuation method, missing information, estimated duty and the date by which a corrected filing will follow. Request written confirmation that the document has been registered and ask how the tax office wants the balance or correction presented. Filing provisionally is not the same as accepting a disputed valuation and, in the right circumstances, it can avoid the far worse position of having no declaration at all.

B. How to correct the return, challenge the charge and establish responsibility

The safest sequence is usually to stop the delay first and argue the amount in parallel. Send the declaration or correction with a cover letter headed with the deceased’s name, date of death, tax number if known and the words déclaration de succession tardive – demande de prise en compte et contestation des pénalités. In English, that means a late inheritance declaration with a request for registration and a challenge to the surcharges. State which figures are accepted, which remain provisional and which penalties are disputed. Pay the amount that is not genuinely disputed where possible, or make a properly documented request for deferred or fractionated payment. Keep a complete copy and proof of delivery.

The evidence for a surcharge challenge should address causation and chronology, not merely hardship. Useful documents include:

• the date the family instructed the notary and the date each requested document was supplied;
• letters showing that a UK bank, insurer, pension provider or probate registry delayed a response;
• evidence of a genuine title-registration or property-valuation issue;
• records showing that a provisional return or payment was offered;
• proof of the date on which the formal notice arrived and the date of the response;
• bank evidence explaining why the estate could not pay immediately; and
• an amended schedule identifying any omitted asset and explaining why it was omitted.

A separate response is needed if the French tax office asks about a bank account, shareholding or debt that was not stated in the declaration. Article R*19-1 of the French Book of Tax Procedures provides that, after a formal notice in this specific procedure, the interested persons have three months to establish that the asset was outside the estate or to pay the corresponding duty and penalties. Its purpose is not the same as the general filing deadline. Answer the request point by point, attach the bank or probate evidence and do not let a request about one omitted asset cause the whole correction to be abandoned.

If the tax office has made a mathematical or legal error, frame the request as a tax claim for correction or restitution, with the notice and calculation attached. If the family seeks discretionary relief because the surcharge is disproportionate to the circumstances, identify that request separately from the legal challenge. A goodwill request should not replace a formal claim where a deadline may run. The route and time limit depend on whether the problem concerns the declaration, a notice of payment, a formal rectification procedure or a professional’s conduct, so the correspondence should identify the decision being challenged.

The French courts have repeatedly treated the filing deadline as a real professional-risk issue where a notary has taken charge of the succession. In Cour de cassation, First Civil Division, 6 March 1984, no. 83-11.445, the published decision approved the finding that the notary should have informed the client of la nécessité de souscrire une déclaration, fût-elle provisoire and of the risk of tax penalties. The point is practical for a British family: uncertainty about accepting the inheritance or about the final valuation does not necessarily justify waiting without filing or paying an amount that can be provisionally assessed.

In Cour de cassation, First Civil Division, 30 March 1994, no. 92-16.666, the Court upheld a finding that the notary had failed to advise the client about l’obligation de souscrire dans les délais une déclaration de succession and the fiscal consequences of missing it. A UK heir should therefore request the full file: engagement letter, time records, drafts, emails, requests for documents, any estimate of duty and every communication about the deadline. A verbal assurance that “the notary is handling it” is difficult to test after a penalty has been imposed.

Cour de cassation, First Civil Division, 8 July 1997, no. 95-13.718, concerned a late succession declaration, failure to advise about the consequences and the availability of fractionated payment. The Court accepted that the loss could be analysed as une simple perte de chance. This does not mean that every penalty is recoverable from a notary. The heir must show what timely advice would have allowed: a provisional return, a payment request, financing, a corrected valuation or another step that had a realistic prospect of reducing the loss.

The same caution appears in Cour de cassation, First Civil Division, 26 November 2002, no. 99-17.745, a published decision concerning a request for an extension and the absence of funds. The Court required the notary to have personnellement averti son client des sanctions encourues. A notary’s request to the tax administration is not automatically enough if the client was not personally warned that the statutory period had expired and that a surcharge could follow. Preserve evidence of what was and was not explained.

In Cour de cassation, First Civil Division, 14 October 2010, no. 09-14.446, the case record addressed the distinction between a letter to the administration and a declaration, the possibility of a provisional filing and the significance of a formal notice. That decision is a warning against treating an informal exchange as a completed return. The file must show what document was delivered, whether it contained enough information to be registered and whether a formal notice had already started a special response period.

Where heirs argue about the applicable law or the value of an asset, payment can remain necessary while the dispute is pursued. Cour de cassation, First Civil Division, 1 February 2012, no. 10-28.760, dealt with a succession dispute and the proposition that le paiement de ces droits devait intervenir nonobstant le litige. The exact consequences depend on the procedural posture, but the message is clear: separate an appeal against the tax calculation from an unexplained refusal to file or pay. If a refund later becomes due, the payment record protects the claim.

The administrative courts have also distinguished late interest from declaration surcharges. In Conseil d’État, Section, 22 April 2005, no. 257254, the Court examined the interaction of the sanctions applicable to a late or inaccurate declaration. The precise cap and combination must be checked against the version of the Code and the facts of the assessment. The decision is useful because it prevents a family from accepting a global figure without asking which legal provision supports each line: Article 1727 interest, Article 1728 late-declaration surcharge or Article 1729 surcharge for an alleged inaccuracy or deliberate omission.

There are two different responsibility routes. The first is against the tax administration: prove the wrong deadline, wrong asset scope, wrong treaty treatment, wrong rate, wrong start date or lack of legal basis, and pursue the appropriate claim. The second is against a professional: prove the instruction, the duty, the failure, the opportunity that was lost and the financial loss. A notary may have warned the family but been unable to file because essential documents were withheld; conversely, a family may have supplied everything while the notary failed to warn them or to send a provisional return. The correspondence must be assessed chronologically rather than by looking only at the final penalty.

For a UK heir, a short cross-border statement should be attached to any challenge. It should explain the UK probate timetable, the relationship between the UK and French representatives, the date each provider responded, the treaty analysis and the exact correction requested. If a UK inheritance-tax payment has been made, attach the HMRC calculation and identify the asset against which relief is claimed. Do not claim a credit twice or subtract a UK tax payment from the French estate without tracing the treaty rule. Ask the tax office to confirm whether it requires an official certificate of French payment, a certificate of non-exigibility or an amended form.

Finally, audit the corrected file before sending it. The audit should confirm that names and dates match the civil records, sterling values use a stated conversion date and method, French immovables are supported by a defensible valuation, debts are evidenced, lifetime gifts are considered, the UK and French tax positions are reconciled, every form is signed and every attachment is listed. Keep an English working copy for the family, but send the French administration the forms and explanations in clear French or with an accurate French translation where needed. A bilingual summary is useful; an untranslated bundle of UK documents is not a substitute for a French declaration.

Conclusion

A late French inheritance-tax declaration is urgent, but it is not a reason to surrender every surcharge without analysis. A British heir should first calculate the correct Article 641 deadline, test the narrow Article 641 bis extension, identify the assets caught by Article 750 ter and then apply the 1963 France–UK inheritance-tax convention to the double-tax question. The filing should be lodged or corrected with a complete evidence pack, even if one valuation or treaty point remains provisional. Interest under Article 1727, a declaration surcharge under Article 1728 and an allegation of inaccuracy under Article 1729 are different legal charges and should be itemised separately. If a formal notice has arrived, the ninety-day period for a succession declaration can be decisive. If a notary controlled the process, the case law makes the advice, provisional-filing and payment history central to any negligence claim. The practical objective is to stop the penalty clock, protect the estate’s position and make the administration or court decide each disputed point on a documented record.

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