Three deadlines carry most of the risk in a Luxembourg company's year. The annual accounts must reach the register within 7 months of the financial year-end. The tax filing is a single return (modèle 500) covering corporate income tax, municipal business tax and net wealth tax, and it is due by 31 December of the year following the tax year.
VAT runs on its own clock: monthly / quarterly returns due before the 15th of the month following the period, filed electronically via eCDF. Everything else is either a short fuse lit at incorporation or a quarterly advance falling on a fixed day, and the tables below have all of them.
Dates here were verified in August 2026 against the ACD's fiscal calendar and its filing-deadline page, guichet.public.lu and the LBR.
The recurring calendar
Once the company trades, the same set of dates repeats every year. Advances are the part founders miss, because nothing arrives in the post to remind them. The tax office sets them from your last assessment and expects them on the fixed days whether or not the current year is going well.
| Obligation | Deadline | Filed with |
|---|---|---|
| VAT return (monthly or quarterly) | monthly / quarterly returns due before the 15th of the month following the period, filed electronically via eCDF | AED, via eCDF |
| VAT franchise turnover declaration | before 1 March, for the previous calendar year | AED |
| Corporate income tax advances | 10 March, 10 June, 10 September and 10 December | ACD |
| Municipal business tax advances | 10 February, 10 May, 10 August and 10 November | ACD |
| Net wealth tax advances | 10 February, 10 May, 10 August and 10 November | ACD |
| Annual accounts approved and filed | within 7 months of the financial year-end | RCS (LBR) |
| Modèle 500 return | 31 December of the year following the tax year | ACD, via MyGuichet.lu |
| Balance of tax assessed | one month after receipt of the tax assessment | ACD |
Two notes on that table. There is one return, not three: the net wealth tax return runs on the same clock as the rest of the modèle 500, 31 December of the year following the tax year, applied to net wealth tax returns for the first time for tax year 2023.
And the return deadline is generous by European standards, which is exactly why it slips. A filing due at the end of next year feels like nothing in March, and the bookkeeping it rests on then has to be reconstructed under time pressure.
A first-year company usually has advances of zero, then receives a catch-up assessment once the first return is processed. It is the most common cash-flow shock in year two. Provision the first profitable year's tax rather than spending it.
The clocks that start at incorporation
The start-up filings run on short fuses. Several of them start counting from the day activity begins rather than the day the company is registered, and those two dates are rarely the same.
Already trading
Photograph the invoice. Send it in. Everything else is handled
Bookkeeping, VAT returns and annual accounts by a licensed Luxembourg firm, from €250 a month. You keep access to your own records.
See how it works| Filing | Clock | Filed with |
|---|---|---|
| RCS registration and publication | 1 month after signing | LBR |
| RBE beneficial-owner declaration | within 1 month, and again on every ownership change | RBE (LBR) |
| VAT déclaration initiale | within 15 days of starting activity | AED |
| CCSS affiliation of the self-employed manager | within 8 days of starting activity | CCSS |
A registration duty is also due on the incorporation deed, collected by the AED. It is a fixed amount rather than a percentage of capital, so it does not scale with the size of the company.
The RBE is the one that quietly goes stale. Beneficial owners go in at incorporation — the test is a controlling shareholding, set by the anti-money-laundering rules — and the register expects an update within the same window every time ownership moves. A share transfer agreed between founders over a weekend starts a filing clock nobody in the room is thinking about.
The business permit sits in front of all of this, on its own timetable. It carries a €50 stamp duty and a decision window of up to 3 months; silence beyond that window counts as tacit authorisation. Once issued, the permit number belongs on invoices and correspondence.
VAT: which rhythm you land in
Turnover decides your filing frequency. Below €112,000 returns can be annual; between €112,000 and €620,000, quarterly; above €620,000, monthly. Cross a band and the rhythm changes with it, which is why a good year is also an administrative event.
Below €50,000 of turnover, tolerated to €55,000, the small-business franchise applies: no VAT charged and no periodic returns. The exemption is not silent, though. Franchise businesses still declare the previous year's turnover before 1 March each year. Registration is a separate step from filing, and we cover it in the VAT guide.
Year-end: the accounts
The 7-month window is not one deadline but two clocks in sequence: the shareholders' meeting approves the accounts, then the approved accounts are filed with the register in the following month. A meeting held late eats the filing time. That, and not neglect, is the ordinary reason accounts land late: an AGM that slipped because nobody treated it as a deadline in its own right.
The filing is made online with the RCS and mentioned in the RESA, the electronic gazette. It is also why your accounts are not private: they are a public record, and banks, landlords, partners and competitors read them. Who must file:
| Entity | Annual accounts filing |
|---|---|
| Capital companies (Sàrl, Sàrl-S, SA, SECA, cooperatives, SE) | Required, every year |
| Partnerships (SENC, SCS) | Required |
| Sole traders | Required above the turnover threshold set for small traders (excl. VAT) |
| Luxembourg branches of foreign companies | Required |
Two pieces of plumbing sit behind the filing, and both are worth knowing by name. The accounts are prepared and validated on eCDF, the state's electronic platform for financial data, and the bookkeeping behind them follows the standard chart of accounts (plan comptable normalisé). That is why "we kept our own spreadsheet categories" always ends in a re-mapping exercise: the state defines the categories, not the company.
The tax return has its own plumbing. Electronic filing is mandatory via MyGuichet.lu since tax year 2017 for resident capital companies, including the s.à r.l. and the s.à r.l.-S, and a LuxTrust product (private or pro) is required both to use MyGuichet and to sign the return. A manager without a working certificate cannot sign the return. Discovering that in the last week of December is a needless emergency.
What being late actually costs
Lateness is priced on two separate tracks: the register's and the tax office's. On the tax side the amounts are published.
| Situation | The charge |
|---|---|
| Return filed late | a supplement of up to 10% of the tax assessed |
| Tax unpaid at its due date | 0.6% per month |
| Agreed instalment plan | interest-free up to 4 months, then 0.1% to 0.2% a month on longer plans |
Tax is payable one month after receipt of the tax assessment, and the instalment route has to be asked for before the end of the month following receipt of the tax assessment. Ask later than that and you are negotiating from a worse position. Asking early is normal and unremarkable; going quiet is what turns a payment problem into an enforcement one.
Common questions
Four questions come up more than any others once the first calendar is drawn, and each one turns on a deadline rather than on a judgement call.
What happens if the annual accounts are filed late?
The register records the filing date, so the delay is visible to anyone pulling an extract, and late deposits attract a surcharge on the register side. If the tax return slips with them, the ACD can add a supplement of up to 10% of the tax assessed, plus 0.6% a month on tax unpaid at its due date.
Does a dormant company still have to file?
Yes. A company with no activity still files its accounts and its return, and still owes the minimum net wealth tax: €535 a year for a balance sheet up to €350,000. A company that stops filing does not stop existing. It accumulates.
When is the first return due for a company incorporated mid-year?
The first tax year runs from incorporation to the first financial year-end, and the return for it is due on the standard clock: 31 December of the year following the tax year. Advances for that first year are typically nil, so the first real payment arrives with the first assessment.
Can a filing deadline be extended?
An extension is available only on a reasoned request addressed to the competent tax office, preferably by fax or post. No period is published, so it is a request rather than a right, granted on reasons rather than on having been busy.
What to do in the first year
- Put every date above in one calendar, owned by one person or one provider, each with a buffer week before the statutory day.
- Book monthly, not annually. The work is the same either way. Half a year of receipts in a shoebox turns an afternoon a month into an expensive excavation at year-end.
- Fix the electronic access early, while nothing is due — the certificate needed to sign the return, and the eCDF access behind the accounts.
- Treat every change as a trigger. New shareholder, RBE. Crossed a turnover band, VAT frequency. First hire, employer registration. The calendar is stable until the business changes.
- Keep the records. Accounting records and invoices are kept for 10 years, in Luxembourg. The obligation outlives the deadline that created the document.