Invoicing in Luxembourg: the details to check

The work is complete, but the invoice comes back with a request for correction. A trade name has replaced the client company, the service period is missing, or the VAT treatment is not explained. These details delay payment and complicate the accounting file. Before choosing an attractive layout, let us create a document that makes it possible to understand who is invoicing what, to whom and under what conditions.

Identify the correct legal entity

Use the supplier's identity and the client's identity from the documents governing the relationship. A trade name, an establishment and a parent company are not interchangeable. If your contact asks you to invoice another entity, obtain an explanation and check who actually ordered the service. The mere fact that two companies belong to the same group is not sufficient to substitute one for the other.

Prepare a validated client file: company name, address, administrative contact and useful tax information. Distinguish the registration number in the register from the VAT number. They do not serve the same purpose. For your own business, also check the details relating to its legal form and its authorisation, where applicable. Keep the date of the latest check.

Describe work that the client can recognise

Avoid lines such as “miscellaneous service” where the file allows for a precise description. State the goods or service, the quantity or scope, as well as the relevant period. An order reference helps link the documents, but it must not be the only element understandable to the person reviewing the invoice.

Distinguish the issue date from the completion date where they differ and must appear. For work carried out in several phases, reconcile amounts already invoiced with new items. A deposit omitted from the final invoice may result in part of the price being claimed twice. Contract monitoring should make this reconciliation straightforward.

Decide on the VAT treatment before calculating

First determine the nature of the transaction, the client's status, the countries concerned and the relevant rules. Do not choose “without VAT” solely because the client is foreign or has a number. Checking the number is a supporting document in the file; it does not replace the analysis of the supply or service.

Organise taxable amounts and taxes according to the applicable treatment. Show the justification and the required details in the event of exemption or reverse charge. For recurring situations, ask the firm for a matrix suited to your activities, including the cases that require its opinion. This is safer than a menu of rates used without explanation.

Organise numbering and corrections

Assign the number at the time provided for in your invoicing procedure and prevent duplicates between users. If you use several series, document their purpose: establishment, activity or another justified organisation. The person responsible for the accounting must be able to understand the series and find the documents without having to reconstruct your method each month.

After issue, do not silently replace the file sent with a different version. Keep a record of the original document and the correction. Depending on the issue, a corrective document or a credit note may be required. Link them clearly. An invoice rejected by a portal and an invoice commercially cancelled are two events that need to be explained, not two equivalent buttons.

Prepare payment and transmission

Separate required details from payment convenience: reference to be used, verified bank details, agreed due date and contact for questions. Check a change of IBAN through a known channel before changing the template. This organisational precaution reduces the risk that a correctly calculated document nevertheless directs payment to the wrong account.

Send the invoice through the correct channel and retain usable proof of sending or submission. A PDF sent to an operational contact may remain invisible to the department that pays. For a public client, check the requirements for a structured invoice and the requested references. Then organise payment follow-up using your aged receivables balance.

The table to take action

Your preparation checklist

• Validate the client entity before issue.
• Reconcile the description, period and order.
• Have unusual VAT situations confirmed.
• Check deposits and discounts.
• Check the number, dates and recipient.
• Archive the version sent and proof of transmission.
• Track corrections and payments without overwriting the history.

Frequently asked questions

Does a foreign VAT number always permit an invoice without VAT?

No. The transaction, its place of taxation and the applicable conditions must be assessed. The number does not answer all these questions.

Is a simple PDF sufficient for a public client?

Do not assume so. The public contracts and concessions concerned require a compliant electronic invoice, transmitted through the appropriate channel.

Should the same template be used for all clients?

A common basis is useful, but the fields and details must correspond to the client's status and the actual treatment of the transaction.

Useful terms in this guide

• Sales invoice
• VAT number
• VAT reverse charge
• Credit note or credit memo

Questions to ask the professional

• Which categories of transactions should we distinguish in our software?
• Which cases need to be validated before sending?
• How should we document our corrections and our number series?

To clarify the assignment to be entrusted, also consult our taxation file.

And for your situation?

Take three invoices representative of your business and run them through this grid. You will quickly identify the information missing from your process. To review the required details and VAT treatment of your transactions, search our directory for a professional to whom you can present these examples and your contracts.