A Sàrl caps at 100 shareholders, and its shares cannot go to a non-shareholder without holders of at least three quarters of the capital agreeing. An SA needs 30,000 € with capital fully subscribed and at least one quarter paid up at incorporation, and its shares move freely. Founders raising outside capital eventually hit the constraints of the limited liability company, forcing a structural transformation to admit the next round of investors.
The initial capital thresholds dictate the starting structure
Most projects begin in the simpler form, which requires 12,000 € for a standard Sàrl. A simplified version exists with a minimum of 1 € and a ceiling of 12,000 €, provided it has at least 1 and at most 100 shareholders. Founders choosing a legal form in Luxembourg weigh this flexibility against the eventual need to convert once the cap table expands.
The initial cash burden is eased by the Law of 18 May 2026 amending the amended Law of 10 August 1915 on commercial companies, which introduced deferred paying-up of the minimum share capital of limited liability companies. The company can delay paying up the cash portion of its minimum capital for up to 12 months. The simplified form goes further, as for a SARL-S the deferred paying-up option covers the entire share capital subscribed at incorporation.
This deferral does not affect every type of founder. The relief applies strictly to cash. If a founder injects intellectual property or equipment instead of money, shares issued on incorporation in consideration for contributions in kind must still be fully paid up at incorporation — only cash contributions can be deferred. The legislation draws a hard boundary here: physical and intangible assets offer no deferred timeline, and the administration expects them to be fully paid up at incorporation.
The incorporation deed locks in the operating rules
Setting up a standard Sàrl requires a notarial deed — the company must be formed in the presence of a notary. Handling the deed and the registry submissions is the core of company formation in Luxembourg, and the drafting must anticipate future funding rounds.
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The text of that deed is highly regulated, and the administration dictates a long list of mandatory clauses. The rule is as follows: The page states: 'L'acte de constitution comporte obligatoirement des dispositions fixées par la loi, telles que :' followed by — l'identité de la ou des personnes physiques ou morales qui ont signé l'acte ou au nom de laquelle ou desquelles il a été signé ; la forme de la société et sa dénomination ; le siège social ; l'objet social ; le montant du capital souscrit ; les catégories de parts ; les spécifications des apports en nature ; le régime des avantages particuliers attribués lors de la constitution de la société ; le cas échéant, le nombre de titres ou de parts non représentatifs du capital exprimé ainsi que les droits y attachés ; dans la mesure où elles ne résultent pas de la loi, les règles qui déterminent le fonctionnement de la société, son administration et surveillance ; la durée de la société ; le montant, au moins approximatif, des frais. Note that the list is introduced by 'telles que' (illustrative, not exhaustive), that the securities item applies only 'le cas échéant', that the operating-rules item applies only to the extent the rules do not already result from the law, and that the costs figure need only be 'au moins approximatif'.
This means the document must map out the identity of the signatories, the chosen corporate form, the registered office, and the corporate object. It must also detail the subscribed capital, the categories of shares, and any specifications regarding contributions in kind.
The requirement explicitly states that the securities item applies only when applicable, meaning a simple capital structure does not force the drafting of complex security rights. The operating rules only need to be written into the deed to the extent they do not already result from the law. What remains unknown until the final signature — such as the exact final cost of the notary and registration — is handled by the allowance that the fees need only be approximate.
The Sàrl-S exception bypasses the notary entirely
Founders who begin with the simplified form avoid the notary entirely, as the structure only requires a private deed — a notarised document is not required. If they later outgrow the ceiling and transform the company, the decision to change form rests with a meeting of shareholders.
The simplified form also carries a strict time limit: founders have exactly 1 to adjust their structure if they breach the parameters of the Sàrl-S. This ceiling does not affect an SA, which operates without a maximum capital limit.
The transformation sequence to admit new investors
When a cap table expands beyond the initial circle, the company must change its legal form to an SA to issue shares freely. The business continues, but the operating rules shift entirely. By law, a change of legal form entails neither dissolution of the company nor the creation of a new legal personality. This continuity means the company does not face dissolution, and no new entity is created to hold the assets.
The conversion from a Sàrl to an SA follows a strict statutory order to turn a signature round into a notary appointment.
| The transformation step | The statutory requirement |
|---|---|
| The financial assessment | A condition precedent is a report by a réviseur d'entreprises on the financial statement summarising the company's assets and liabilities. |
| The shareholder vote | The required majority is at least two-thirds of the votes cast, at either of the two meetings. |
| The authentic act | The strict rule is that the absence of an authentic deed is a ground of nullity of the transformation wherever such a deed is required. |
| The registry update | The filing mechanism dictates that filings are made electronically. |
The publication date controls the effect on third parties
Signing the deed does not immediately bind the outside world. By law, the transformation takes effect against third parties only after publication in the RESA.
The exact timing of this visibility is managed during the submission. For any such update, the deed is published in RESA on the day of filing, or on a fixed date chosen by the filer when creating the filing request, within a limit of 15 days after filing. Until that publication clears, the company remains a Sàrl to anyone querying the registry. What the administration does not publish is the exact internal processing time it takes to validate the electronic filing before it hits the RESA publication queue; the filer only controls the requested date, not the registry's internal workflow.
The registry filings carry strict deadlines and severe penalties
The administration strictly polices the timeline for corporate updates. The general baseline is 1 month after signing. However, for a change in legal form, the mandate is specific: the company has a maximum of 1 month to file.
The filing duty extends beyond the statutes themselves. At the RCS, extracts of deeds relating to the appointment and termination of office of directors, managers or administrators must be filed. Missing these registry deadlines is not merely an administrative oversight. The law defines a breach of professional integrity as failing, on at least two occasions during the last three financial years, to meet the filing and publication obligations under the Trade and Companies Register law. This penalty isolates repeat offenders; it does not catch a founder who misses a single deadline by a few days, as the integrity bar requires at least two failures over three years.
The RBE and UBO declarations follow the RCS
Admitting new investors also shifts the beneficial ownership map. The company must update the Register of Beneficial Owners, which carries a strict 1 month deadline. Alongside this public registry, the banking sector demands its own documentation: the separate UBO declaration is required by current CSSF regulation, and it supplements rather than replaces the extract from the Register of Beneficial Owners.
If a company needs more time for its tax-related filings during this transition, an extension is available only on a reasoned request addressed to the competent tax office, preferably by fax or post. This extension rule only applies to the tax office; it does not grant the company any additional time to file its corporate changes with the RCS or the RBE.
The corporate documents must state the current form
Once the registry confirms the transformation, the company's own outbound paperwork must change to match its new legal reality. For a company operating as a Sàrl, the company's documents must state the company name, the words 'société à responsabilité limitée', the registered office, the RCS registration number and the capacity of the signatory of the document (the share capital mention is no longer obligatory).
The update applies to every invoice, letterhead, and official communication the company issues. The designation belongs to the registered reality, not the historical name. The share capital mention is explicitly excluded from this requirement, meaning the company does not need to reprint its stationery every time a new funding round increases the capital.
Figures verified against guichet.public.lu, guichet.public.lu, guichet.public.lu, guichet.public.lu, guichet.public.lu, data.legilux.public.lu, guichet.public.lu, legilux.public.lu on 2026-10-26.