FAIA (Fichier d'Audit Informatisé) is Luxembourg’s standardised electronic tax audit file. When the tax authority (the AED) conducts a VAT audit, they can request a copy of your accounting data in this specific format. It is based on the OECD’s Standard Audit File for Taxation (SAF-T) framework, adapted for Luxembourg’s VAT rules and French-language accounting conventions. Any VAT-registered business in Luxembourg with annual turnover exceeding €112,000 must be able to produce a compliant FAIA file when asked.
Quick reference: FAIA is not submitted routinely. It is an on-demand file: the AED requests it specifically during VAT audits. However, businesses must maintain the ability to produce it at any time.
Where FAIA Comes From
The OECD published the SAF-T standard in 2005 as a recommended format for sharing accounting data electronically between businesses and tax authorities. The goal was a universal, machine-readable format that simplifies tax audits while reducing the burden on businesses. Luxembourg adopted SAF-T and implemented it as the FAIA standard, tailoring it to local VAT requirements and French-language accounting terminology.
The current version is FAIA v2.01. The official technical specifications are published by the Luxembourg tax authority at pfi.public.lu.
Who Must Comply?
The FAIA obligation applies to all VAT-registered taxpayers in Luxembourg whose annual turnover exceeds €112,000. This threshold captures the majority of commercial entities operating in the country, including:
- •Domestic companies (S.A., S.àr.l., S.C.A., etc.) with Luxembourg VAT registration
- •Luxembourg branches of foreign companies registered for VAT purposes
- •Partnerships and sole proprietorships above the turnover threshold
- •Investment funds and financial institutions subject to Luxembourg VAT
Businesses below the threshold are exempt but may still choose to maintain FAIA capability as a good practice, particularly if they expect growth or want to be ready for future audit requests. This threshold is set out in the AED’s FAIA implementation guidance, available at pfi.public.lu.
The Three Variants
Luxembourg defines three official FAIA variants. The difference between them is how much data the tax authority asks you to provide. The AED will specify which variant they need when they make their request.
Full Version
The most comprehensive variant. It includes your complete chart of accounts, all customer and supplier records, tax code definitions, product listings, stock records, asset registers, and the full set of journal entries. On the transaction side, it covers sales invoices, purchase invoices, payments, stock movements, and asset transactions. This is the default variant for most audit requests.
Reduced Version A
A simplified variant designed for smaller businesses or more targeted audit requests. It includes a subset of the master data and transaction records, reducing the data preparation effort while still providing the tax authority with the essential financial information they need.
Reduced Version B
An alternative reduced variant covering a different combination of data. The choice between Reduced A and Reduced B depends on what the AED specifically requests. Your accounting software should be capable of generating all three variants.
What Data Does a FAIA File Contain?
A FAIA file is organised into three main sections. Understanding what goes into each section helps you keep your data audit-ready.
Header
Identifies your company (name, VAT number, address), the fiscal year covered, the software used to generate the file, and the audit period. The header must include Luxembourg ("LU") as the country code and EUR as the default currency.
Master Data
This section contains the reference data that your transactions link to. It includes:
- •Chart of accounts with account types classified using the French terms: Actif (asset), Passif (liability), Produit (income), Charge (expense)
- •Customer records for everyone you have invoiced during the period
- •Supplier records for everyone you have received invoices from
- •Tax codes listing Luxembourg TVA rates: standard (17%), intermediate (14%), reduced (8%), and super-reduced (3%)
- •Journal entries linking to accounts in your chart of accounts
Transactions
The transaction section contains the actual business activity during the audit period:
- •Sales invoices with line items, tax amounts, and links to customer records
- •Purchase invoices with supplier references and expense details
- •Payments linking to invoices and bank accounts
- •Stock movements and inventory records
The On-Demand Process
Unlike some European countries that require periodic SAF-T submissions, Luxembourg follows an on-demand model. The AED requests FAIA files only during VAT audits, typically specifying the fiscal period and how much detail they need (which determines the variant). Businesses generally have a defined response window to produce and deliver the file.
This means that while you may not need to generate FAIA files frequently, your systems must always be ready to produce valid ones. Discovering compliance issues for the first time during an active audit creates delays and may lead to penalties.
Common Compliance Mistakes
Based on common patterns seen during FAIA validation, these are the mistakes that most frequently cause files to be rejected or queried. For a deeper look at each one, see our guide to common FAIA validation errors and how to fix them.
- •Incorrect file identification: The file does not correctly identify itself as a FAIA v2.01 file, often because the accounting software is configured for an older version
- •Missing cross-references: Invoices reference customers or suppliers that are not listed in the master data section
- •Invalid TVA codes: Using tax codes from another country or non-standard codes instead of the official Luxembourg TVA codes
- •Wrong account type labels: Using English terms (Asset, Liability) instead of the required French terms (Actif, Passif, Produit, Charge)
- •Date format errors: Using local date formats (DD/MM/YYYY) instead of the required YYYY-MM-DD format
- •Rounding and precision issues: Tax rates or monetary amounts without the required two decimal places
- •Data in the wrong order: Information appearing in a different sequence than the official specification requires
How to Stay Compliant
Maintaining FAIA compliance requires attention in three areas: your accounting software setup, your data quality practices, and your validation routine.
- •Check your software setup: Confirm that your accounting system is configured to generate FAIA v2.01 files with the correct Luxembourg tax codes and French account type labels
- •Keep your master data clean: Make sure customer, supplier, and account records are consistent and that nothing referenced in your transactions is missing from the master data
- •Validate regularly: Run your FAIA exports through a validator periodically to catch issues before they build up
- •Stay updated: Monitor the AED website for specification updates and new requirements