Corporate tax advances in Luxembourg: due dates, calculation and adjustment

In short. A Luxembourg company does not pay its tax in one go: it pays quarterly advances requested by the Luxembourg Inland Revenue (Administration des contributions directes), before the year's result is even known. The due dates differ by tax: corporate income tax (CIT) is paid on 10 March, 10 June, 10 September and 10 December; municipal business tax and net wealth tax, on 10 February, 10 May, 10 August and 10 November. Each advance is in principle a quarter of the last assessed tax. The amount can be adjusted on a reasoned request, which spares you many cash-flow surprises.

Many directors discover tax advances the day a notice lands, asking for an amount that matches nothing they had in mind. Yet the mechanism is not obscure once laid out: the tax office makes you pay in advance, in instalments, a tax it will settle later. Here is how these advances are calculated in Luxembourg, on which dates they fall, and how to adjust them when they no longer match your company's reality.

What is a tax advance in Luxembourg?

A tax advance is a quarterly instalment your company pays on a tax that will only be calculated definitively later, once the return has been processed. The Luxembourg Inland Revenue requests these advances through an advance payment notice, based on the last known tax. They do not add to the final tax: they are set off against it. In the end, you only pay the balance between the tax actually due and what you have already paid.

Three company taxes work this way: corporate income tax (CIT, impôt sur le revenu des collectivités), municipal business tax (impôt commercial communal) and net wealth tax (impôt sur la fortune). Their calculation is detailed in our article on corporate tax in Luxembourg; what concerns us here is their staggered payment.

The three calendars not to confuse

Here is the point that trips people up most: the advances do not all fall on the same dates. CIT follows one calendar, municipal business tax and net wealth tax follow another. Here are the due dates set by the Luxembourg Inland Revenue.

The concrete result: a company subject to all three taxes actually has a tax due date almost every month, alternating. These dates come on top of the VAT and accounts-filing deadlines we bring together in our accounting and tax calendar for a Luxembourg company. Recording them once and for all in a schedule saves you from meeting them one surprise at a time.

How is the advance amount calculated?

The principle is simple: each advance is in principle a quarter of the tax resulting from the last assessment established, after setting off any withholding taxes already applied. In other words, the tax office takes your last known tax, divides it by four, and asks for that quarter at each due date. Until a new assessment is established, the advances stay anchored to that last figure.

This mechanism has a consequence few directors anticipate: advances look in the rear-view mirror. They reflect a past year, not the current one. For a stable company, the gap is small. For a company on the move, it can be large, and in either direction.

The trap for a young or growing company

This is where the mechanism deserves some attention. A newly formed company has no established assessment yet: its first advances are therefore low, even nil. The director feels safe, until the first tax assessment arrives and asks for the tax of two years at once, with almost no advances to absorb it. This is not a tax-office error; it is the normal lag between real activity and a system anchored to the last known tax.

Same logic for a fast-growing company: its advances, based on a smaller year, stay behind its real profits. The final balance grows accordingly. Conversely, a company whose activity is shrinking keeps paying advances anchored to a strong year, tying up cash it will only recover later. In both cases, letting the advances run on their own is costly in cash terms.

How to adjust your advances

Good news: the amount is not set in stone. The Luxembourg Inland Revenue can change it in two ways. On its own initiative, if it holds evidence justifying a reduction or an increase. Or, more useful to you, on a reasoned request from the taxpayer. In practice, if you know your current year will be very different from the last assessed tax, you can ask for your advances to be adjusted, with figures to back it up.

A credible request rests on data, not on a hunch: a supported forecast result, a documented drop in activity, a heavy investment that flattens the profit. This is exactly what up-to-date bookkeeping lets you produce in minutes. Without recent figures, the request is a mere assertion; with them, it becomes a file. Take care, though, not to understate deliberately: advances that are too low simply push the burden onto a heavier final balance.

What if you don't pay them?

The advances are not optional. Not paying them does not erase the tax: the sums due stay due, and the final balance grows accordingly. Late payment can also generate interest in favour of the Treasury, exactly like a debt. The advances actually paid, for their part, are set off against the tax assessed in the end: nothing is lost, everything is credited.

The real question, then, is not whether to pay them, but how to make their amount match reality and have the cash ready at each due date. An advance that falls without having been provisioned is a cash-flow problem; the same advance, anticipated, is just a line in a plan.

Anticipating tax rather than enduring it

The comfort with advances does not come from a tax trick: it comes from bookkeeping that tells you where you stand before the notice arrives. When your result builds as you go, you know your forecast tax during the year, you know whether your advances are too high or too low, and you decide to adjust or provision with full knowledge.

This is the heart of our model. We keep your books in the Odoo we set up for Luxembourg, your taxable result is calculated continuously, and your file manager tracks the advance due dates along with the rest. You no longer discover a notice, you expect it. The full approach is set out in our guide to accounting firms in Luxembourg, and its price in our article on what an accounting firm costs. The fixed fee starts from €325 per month, all included.

Frequently asked questions

When are a Luxembourg company's tax advances due?

CIT is paid in advances on 10 March, 10 June, 10 September and 10 December. Municipal business tax and net wealth tax are paid on 10 February, 10 May, 10 August and 10 November. A company subject to all three taxes therefore has a due date almost every month, alternating.

How is the advance amount calculated?

Each advance is in principle a quarter of the tax resulting from the last established assessment, after setting off withholding taxes. Until a new assessment is set, the advances stay anchored to that last known figure, which reflects a past year.

Can you reduce your tax advances?

Yes. The Luxembourg Inland Revenue can change the advances on its own initiative, or on a reasoned request from the taxpayer. If your current year is set to be very different from the last assessed tax, you can ask for an adjustment, with forecast figures to back it up.

What happens if I don't pay an advance?

The tax stays due: not paying an advance does not reduce the final charge, it increases it and can generate late interest. The advances paid are set off against the tax assessed in the end, so nothing is lost, everything is credited.

Does a new company pay advances in its first year?

In principle no, or little: with no assessment yet established, the tax office has no basis to set significant advances. The flip side is that the first tax assessment can ask for the tax of several years with few advances to absorb it. It is wiser to provision from the start.

Read more

• Corporate tax in Luxembourg: CIT, municipal business tax and net wealth tax
• The 2026 accounting and tax calendar for a Luxembourg company
• Deductible business expenses in Luxembourg
• Accounting firm in Luxembourg: the complete guide for an SME
• What an accounting firm costs in Luxembourg: fixed fee, hourly rates and hidden extras

Why Advena?

We are the only Luxembourg accounting firm that keeps your books inside the management tool it deployed for you. Your forecast tax is calculated continuously, your advance due dates are tracked by a dedicated manager, and the fixed fee starts from €325 per month, all included. We inform you of the tax rules, we do not replace tailored advice, and we tell you plainly when our model is not right for you.

Information up to date as of July 2026, based on the "Avances d'impôt" page of the Luxembourg Inland Revenue (Administration des contributions directes) (last official update 20 May 2025). This article is for information and does not constitute tailored tax advice.