A Sàrl-S has to become a standard Sàrl on either of two statutory triggers: share capital above €12,000, or more than 100 shareholders — and only the second comes with a published deadline, 1 year.
The decision belongs to a meeting of shareholders, and nothing is wound up on the way: a change of legal form entails neither dissolution of the company nor the creation of a new legal personality, so the RCS number, the contracts and the trading history all carry over.
The form rules below were read on guichet.public.lu in July and August 2026: the Sàrl-S page, the Sàrl page and the page on changing legal form. The register mechanics, the SA figures and the 2026 capital-payment law come from guichet's other pages and from Legilux instead. Where the published pages stop short of an answer, this article says so rather than filling the gap — which is the whole of the notary section below.
The triggers, and the only deadline that is written down
Two of the three reasons founders convert are statutory, and they behave very differently: one you pull deliberately, on the day the shareholders decide to raise the capital line, and one arrives on somebody else's timetable as the shareholder register fills up.
The third reason is purely commercial and carries no rule at all, which also means it carries no deadline you can miss. The table separates the wording of the official pages from what each trigger actually does to your calendar.
| Trigger | What the official page says | What that means for timing |
|---|---|---|
| Share capital | the company must change its legal form if the share capital exceeds EUR 12,000 | No period is published |
| Shareholder count | if the number of shareholders exceeds 100, the SARL-S has one year to change its legal form | The one clock that is written down |
| A company joining the cap table | Eligible holders: only natural persons — a company can never be a shareholder | A standing condition, not a dated event |
Read the capital trigger literally: it is written on share capital, not on reserves, equity or turnover. A Sàrl-S allocates 5% of its annual net profits to a legal reserve, and a reserve building up towards the ceiling is easily mistaken for the thing that pushes a company over the line.
It does not: the legal reserve and the share capital are different lines, and the allocation is not open-ended either — the allocation continues until the legal reserve and the share capital together reach €12,000, and then it stops. The figure that engages the conversion rule sits in the capital line of the statuts, and it moves only when the shareholders decide to move it.
The shareholder ceiling is the trigger with a clock on it. The 1-year period is stated there and nowhere else; no equivalent period is published for the capital trigger. That silence is not permission to sit indefinitely on an over-capitalised Sàrl-S; it means the timing is simply not published, which is a different and slightly worse position to be in than a known deadline.
The third trigger arrives with a term sheet. The natural-persons rule in the table admits no corporate shareholder at all, so a fund vehicle, a family holding or a corporate partner joining the cap table means the conversion happens before the share transfer, not alongside it. That sequencing is where deals slip, because an investor's timetable and the lead time on a transformation's own paperwork do not naturally align.
Nothing forces a conversion for a large client, a public tender or a bank credit line. The standard Sàrl can read as the more established form to a counterparty, and that alone is a reason a founder may convert ahead of a milestone. It has no statutory content, which is exactly why it is the one version of this decision you can take calmly.
What the general transformation regime asks for
Changing legal form has its own regime in Luxembourg law, set out on guichet's transformation page. The three elements below are what that page states for a transformation in general terms.
It is worth establishing early which of them your own file actually turns on, because one of them — whether an authentic deed is required — is the point at which the published wording stops short for a Sàrl-S. The next section deals with that question separately rather than resolving it by assumption.
| Element | The rule |
|---|---|
| The vote | at least two-thirds of the votes cast, at either of the two meetings |
| The numbers | a report by a réviseur d'entreprises on the financial statement summarising the company's assets and liabilities |
| The company's identity | a change of legal form entails neither dissolution of the company nor the creation of a new legal personality |
Two of those repay attention. The majority is measured on votes cast rather than on the whole share capital, and the rule is written to cover either of two meetings. And the réviseur's report is the element with a real lead time attached: it works from a financial statement summarising assets and liabilities, which means the books have to be in a state a professional can sign off, not the state you were planning to tidy up in the spring.
Does the conversion need a notary?
This is where honest sourcing matters more than a confident sentence. A Sàrl-S is incorporated by a private deed — a notarised document is not required. That is most of its appeal.
A standard Sàrl is incorporated by a notarial deed — the company must be formed in the presence of a notary. It is tempting to read across from those two facts and conclude that the conversion therefore requires a notary. That is an inference, and the published pages do not make it for you.
What the transformation page states is narrower, and it is conditional: the absence of an authentic deed is a ground of nullity of the transformation wherever such a deed is required. Read that clause slowly.
It tells you the consequence of a missing deed in the cases where a deed is required; it does not tell you whether a Sàrl-S becoming a Sàrl is one of those cases. Nothing read on the pages above resolves that in terms, so this article does not resolve it either.
That leaves one question worth putting to a notary before anything is scheduled, in close to those words: is an authentic deed required for this transformation, and on what text. It is worth asking early because of the sanction attached to the answer — nullity of the transformation, not a fee.
A conversion carried out in the wrong form is not a conversion that costs more; it is a conversion that may not stand. And if a page tells you flatly that no notary is involved, the reasonable next question is where that is written.
The filing chain, and the date the change becomes real
Once the shareholders have decided, the paperwork runs on the ordinary register machinery rather than on anything specific to conversions. For a Sàrl-S, subsequent changes must be filed at the RCS for publication in the Recueil électronique des sociétés et associations.
The amended statuts carry a filing deadline of 1 month, and filings are made electronically, so the step itself is a portal exercise rather than an appointment. The publication date is yours to set: 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.
That choice matters more than it looks, because the transformation takes effect against third parties only after publication in the RESA. Until the publication date carried on the filing, a bank, a client's legal team or a procurement officer pulling the register still sees a Sàrl-S.
If the conversion exists to satisfy a counterparty, the date they can verify is the publication date, not the date of the meeting — so the signature that depends on the new form should not be scheduled into the gap between the two.
What changes on your paperwork the following week
Because there is no new legal person, the registration does not restart: the RCS number and the existing contracts continue on the same entity. What does change is every place the old form is written down. As a Sàrl-S, the name must appear on all company documents followed by the mention SARL-S.
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).
In practice that is invoices, quotes, the website footer, email signatures, contract templates and any signage. It is the dullest part of the conversion and the easiest to leave half-finished, because no step in the procedure owns it: a deed, where one is required, ends at the deed; the register filing updates the register; and the templates belong to whoever last opened them.
It is also why conversion beats the alternative some founders imagine, which is dissolving the Sàrl-S and incorporating a fresh Sàrl. That route reopens the business permit, the VAT registration, the bank onboarding and every contract novation at once, on a company with no trading history behind it.
Common questions
The questions below stop being theoretical the moment a trigger is real — the moment an investor, a bank or a procurement team asks for the register extract and someone reads the legal form printed on it. Each is answered on this page rather than pointed at, and where the published sources carry no answer, that is said plainly instead of being smoothed over with a confident sentence.
Does the mandatory reserve push the company over the ceiling?
Not by itself. The trigger is written on share capital, while the 5% annual allocation builds a legal reserve — a different line of the balance sheet, and one with a stop built into it: the allocation continues until the legal reserve and the share capital together reach €12,000, and then it stops.
A Sàrl-S can hold reserves and remain a Sàrl-S. What engages the rule is the share capital line itself rising above €12,000, and it rises only by a decision of the shareholders.
How long does the whole conversion take?
The only published clocks are the 1-month filing deadline for the amended statuts and the RESA publication window above. Everything before that — the réviseur's report, the shareholders' meeting, a notarial appointment if a deed is required — runs on availability rather than on a statutory timetable, so no honest end-to-end figure exists to quote.
Can a Sàrl-S convert straight into an SA?
A change of legal form is not limited to the Sàrl as a destination. What changes is what the destination form demands: an SA has a minimum capital of €30,000, with capital fully subscribed and at least one quarter paid up at incorporation. The transformation machinery — the shareholders' decision, the réviseur's report, the filing and publication — is the same.
Has anything changed about starting as a standard Sàrl instead?
Yes, at the front end. Luxembourg passed 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.
A standard Sàrl still needs €12,000 subscribed, but the cash can be paid up within 12 months of incorporation, and 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 rule is wider at the simplified end: for a SARL-S the deferred paying-up option covers the entire share capital subscribed at incorporation. Any comparison of the two forms written before that law is describing arithmetic that no longer applies.
Planning a Sàrl-S with the conversion in mind
Most of what makes a conversion cheap or slow is settled long before it happens, in the statuts and in the state of the books. None of the four points below costs anything at incorporation, and each removes work later, when the trigger arrives on a schedule you may not control.
They read better as design choices for the Sàrl-S itself than as steps in the conversion, which is why they belong at the start of the company's life rather than at the end of it.
- Keep the statuts close to standard-Sàrl logic. The amendment is then a delta rather than a rewrite, and there is less to reconcile when the figures are reviewed.
- Know which trigger is yours. The capital trigger is one you pull; the shareholder and investor triggers arrive on someone else's calendar. They need entirely different amounts of notice.
- Keep the accounts signable year-round. The regime turns on a financial statement a professional has to stand behind, and that is not an exercise to begin the week a term sheet lands.
- Put the publication date in the deal calendar, not the meeting date. Publication is the date a counterparty can verify, and it is the date the change bites on them.
The Sàrl-S was designed as an entry point, and the conversion is its built-in exit rather than evidence the original choice was wrong. If you are at the other end of the path, we set out separately how the Sàrl-S is incorporated without a notary — and the trajectory above is worth mapping before those statuts are signed rather than after.