The glossary to understand and take action

Tax loss carryforward

A loss determined under tax rules whose deduction in a subsequent period remains possible subject to conditions.

Notion comptable, fiscale ou juridique · Luxembourg Fiduciaries Editorial Team · Reviewed on

Understand the scope

Definition and points to distinguish

It must be tracked by taxpayer, tax and year of origin. The accounting balance of losses does not prove the amount still available for tax purposes. Previous uses, the carryforward period and changes in circumstances must be documented.

In your file

What this changes in practice

A tax loss carryforward results from the tax calculation and may be used in other periods under the applicable conditions. It does not automatically correspond to the accounting loss. Its origin, year and applicable limitations must be tracked. A restructuring transaction or a significant change may warrant a specific analysis; the carryforward should not be regarded as immediately available cash credit.

A scenario to help you understand

Educational example

A company becomes profitable again after a loss-making period. It reviews its tax loss statement and the conditions of use before preparing its tax return.

Fictitious situation, presented to illustrate the concept.

Prepare for what comes next

Points to check

  • Rapprocher pertes comptables et fiscales
  • Suivre les pertes par exercice
  • Vérifier les conditions d’utilisation

The practical question

Find out more

Pourquoi conserver un tableau des pertes par exercice ?

Les conditions d’utilisation peuvent dépendre de l’origine et de la période des pertes. Un total global peut masquer des différences de traitement. Rapprochez le tableau des déclarations et décisions fiscales, puis documentez les imputations effectuées. Lors d’une opération importante, ce suivi permet d’examiner les conséquences sans supposer que l’intégralité du montant restera toujours disponible.

Connecting concepts

Terms to know as well

Continue with the concepts, contacts and procedures related to this topic.

Tax returnA tax return provides the administration with the information needed to assess or verify a tax for a given person and period.Corporate income tax (IRC)The term corporate tax commonly refers to the taxation of companies’ profits; in Luxembourg, IRC is one of the taxes to be distinguished.Financial yearThe financial year is the period over which a company prepares its accounts and determines its result.Tax return — Form 500Form 500 refers to the tax return form for entities, with the sections and appendices corresponding to the relevant year and situation.Municipal business taxMunicipal business tax (ICC) is a direct tax linked to commercial profit, the calculation of which notably takes account of a municipal rate.

Put it into practice

Explore further with our guides

Practical guideTax losses: organising tracking and carryforward supporting documents

Sources and verification

References consulted on 20 September 2026. Official procedures specify the applicable conditions and exceptions.

This guide explains a general process. The applicable rules depend on your situation; it does not constitute personalised advice. Report a correction.

A definition gives you a reference point. To examine your situation, clarify your question with a professional.