Digital··6 min
Accounting obligations in Luxembourg: the 2026 calendar and LBR sanctions
For a financial year ending on 31 December 2025, accounts had to be filed with the RCS by 31 July 2026, and the LBR's sanctions phase started on 21 September 2026. This guide is for managers of SMEs and tech start-ups who are not accountants. It covers VAT deadlines, annual accounts, corporate tax and when to hand the work to a fiduciaire (accounting and corporate services firm).
Translated from French · Lire l'original en français
Luxembourg Business Registers (LBR) launched its sanctions phase on 21 September 2026. A company that has not filed its accounts on time can now receive a registered letter, and its file can then be publicly flagged. Below are the 2026 calendar of obligations, the cost of missing them and the cases where it makes sense to hand the work to a fiduciaire.
The LBR sanctions timeline, step by step
According to Paperjam (figures as at 31 August 2026), the LBR had 53,337 files exposed to sanctions. Of these, 38,716 had annual accounts filed late and 2,577 entities had filed nothing for three years. Paperjam also uses a close figure of 53,517, which does not reconcile with the first: rely on the order of magnitude, not the exact number. According to Paperjam and the law firm Loyens & Loeff, both referring to the law of 23 January 2025, the procedure is applied gradually, file by file:
- a registered letter lists the failures;
- after 30 days, a public warning appears when the file is consulted;
- after 60 days, the failures are shown on extracts and certificates;
- after 7 months, a penalty of €40 per day applies for up to 90 days, so €3,600 at most;
- after 12 months, the LBR can strike the company off the register and refer the case to the State Prosecutor (procureur d'État), which can lead to administrative dissolution without liquidation.
Putting things right ends the procedure, but it does not cancel penalties already applied, so acting as soon as the letter arrives costs less than acting in the seventh month. According to Paperjam, 3,430 of the 19,440 letters sent between April and August (17.6%) could not be delivered: check that your company's address in the register is up to date. The LBR's public notice sets out the scheme, but we were unable to read its full text: confirm the starting point of each deadline with the LBR.
The 2026 calendar for non-accountants
The table below brings together the recurring deadlines according to Guichet.lu and the Administration des contributions directes (ACD, the direct tax authority). It does not give an exact day for the “15”: confirm the working day on eCDF or Guichet.lu.
| Obligation | Applies to | Deadline |
|---|---|---|
| Monthly VAT | Turnover above €620,000 | Before the 15th of the following month |
| Quarterly VAT | Turnover from €112,000 to €620,000 | Before the 15th of the following quarter |
| Annual summary VAT return | Monthly and quarterly regimes | Before 1 May of the following year |
| Annual VAT return only | Turnover below €112,000 | Before 1 March of the following year |
| Annual accounts with the RCS | Companies required to file | 7 months after year end (31/07/2026 for a year ending 31/12/2025) |
| 2025 corporate tax | Capital companies | 31 December 2026 |
| IRC advance payments | Companies subject to IRC | 10 March, 10 June, 10 September, 10 December |
According to Guichet.lu, the turnover threshold refers to annual turnover excluding VAT. The monthly regime is the default under the amended law of 12 February 1979, but the Administration de l'enregistrement, des domaines et de la TVA (AED, the VAT authority) alone decides which regime applies to your company. Two points to watch: Guichet.lu's tax calendar page dates from 2023 and gives 31 May for IRC and ICC returns (corporate income tax and municipal business tax), whereas the ACD gives 31 December of the following year for tax year 2025. We follow the ACD, the primary and more recent source, but the discrepancy is worth confirming with the authority. The advance payment dates come from a page updated on 20 December 2023: check them again.
eCDF: who files what
According to Guichet.lu, all VAT returns have gone through eCDF since 1 January 2020, either as an online form or an XML file, using an electronic certificate. Once filed, the return is passed to the AED with no further step. For corporate tax, the ACD has required resident capital companies (SA, SAS, SCA, SARL, SARL-S, SE) to file via MyGuichet.lu since tax year 2017.
On the RCS side, Guichet.lu lists the entities required to file: SA, SARL, SECA, cooperative companies, SE, Luxembourg branches of foreign companies (excluding credit institutions and insurers), GIE, ASBL and foundations. SENC, SCS and sole traders must file if their annual turnover excluding VAT exceeds €100,000. Filing the accounts follows a four-step chain: accounts drawn up under the standardised chart of accounts (plan comptable normalisé), unless IFRS are permitted; validation on eCDF; filing of the package with the RCS using a LuxTrust certificate; notes in PDF/A. The filing notice is published in the RESA within 15 days at most. The accounts must be approved within 6 months of year end, then filed within the following month.
The delays that cost the most
For direct taxes, the ACD (Prélèvements supplémentaires page, updated on 4 July 2025) mentions a late filing surcharge of up to 10% of the tax assessed, a two-stage penalty (formal notice, then decision) whose amount is not published, and an ex officio assessment if a company refuses to file. Late payment interest is 0.6% per month at the full rate, or 0.1% to 0.2% per month when a payment extension has been granted on request. A payment extension requested in time therefore costs far less than an unplanned delay.
For VAT, fine amounts circulate in the specialist press, but we found no official text confirming them: consult the law of 12 February 1979 on Legilux or the AED before putting a figure on a risk. Likewise, the only RCS sanction we can cite with certainty is the LBR penalty described above.
In-house or fiduciaire: the decision grid
The choice depends less on the size of the team than on how often obligations fall due and on the tools available.
| Criterion | Rather in-house | Rather a fiduciaire |
|---|---|---|
| VAT frequency | Annual only | Monthly or quarterly |
| Volume of entries | Low, regular | High or variable |
| eCDF and LuxTrust access | Account and certificate working | No account or certificate |
| Accounting skills | An employee trained in the PCN (standardised chart of accounts) | No dedicated resource |
| Risk of delay | Calendar tracked and checked | Already received an LBR letter |
The more boxes you tick in the right-hand column, the stronger the case for outsourcing, especially if your company has already received a letter from the LBR: the 30-day deadline is running.
Luxembourg fiduciaries such as B&R Consulting handle bookkeeping, VAT and eCDF filings for SMEs that would rather focus on their business.
Can you outsource only part of the work?
Yes, nothing in the sources consulted requires a single package: some companies hand over only the annual accounts and keep VAT in-house. Ask for the exact scope in writing.
What should you do if the 31 July 2026 deadline has passed?
Put things right without delay: according to Loyens & Loeff, regularisation ends the LBR procedure, but does not cancel penalties already applied.
This article is for information only and does not replace personalised legal or tax advice: for your own situation, contact the AED, the ACD, the LBR or a licensed professional.
