How much can a well-prepared tax return save you?

It's a December evening, 11 pm. The filing deadline is looming, and you're ticking boxes somewhat randomly just to get it over with. Sound familiar? You're certainly not alone. Yet a tax return completed in haste often means money left on the table. So, how much can a truly well-prepared tax return save you? We put the question to Patrick Malget, co-founder of taxx.lu, the platform already helping tens of thousands of taxpayers in Luxembourg.

1. Patrick, what difference does a “well-prepared” tax return really make to taxpayers?

A well-prepared tax return is simply one that ensures you claim everything you're entitled to, in the correct section and with the appropriate supporting documents. There's nothing magical about it. It's about making sure you don't overlook deductions that you are perfectly entitled to claim.

And the difference can be substantial. Over the past year, the average tax refund received by taxx.lu users amounted to EUR 2.352. That said, every situation is unique, and the final amount of any refund is always determined by the Luxembourg Inland Revenue (Administration des contributions directes). Our role is simply to ensure that you don't miss out on anything.

2. Which deductions do people most commonly forget?

There are a few that come up time and again. Generally speaking, they're not the most complicated deductions, just the ones people forget to claim:

Mortgage interest

Interest paid on a loan relating to your main residence is tax-deductible. The deduction limit depends on when the property was made available to you. In fact, for the first two years, there is no longer any cap for homes made available on or after 1 January 2024.

Pension savings

For the 2025 tax return, contributions are deductible up to EUR 3.200 per person. Good news for forward planners: from the 2026 tax year, this limit rises to EUR 4.500 per person.

Insurance premiums and personal loan interest

These share the same deduction limit of EUR 672 per member of the household. For a family of four, this is a deduction that should not be overlooked.

Charitable donations

Donations made to recognised organisations are deductible once they reach EUR 120 during the year, up to a maximum of 20% of your net income.

Extraordinary expenses

Unavoidable expenses that place a significant burden on your household budget may reduce your tax liability, such as substantial unreimbursed medical costs. Childcare expenses, meanwhile, are covered under a separate allowance. In all cases, these are not simply boxes to tick: you need to provide the relevant information and keep your supporting documentation.

Tax allowance for children not living in the household

This allowance amounts to EUR 5.424 for 2025, but it does not appear automatically. You must claim it yourself. This is exactly the sort of omission that can prove costly.

Top tip:
Before you begin, gather all the documents you received at the start of the year (insurance statements, certificates, childcare expense records, etc.). It will save you valuable time and help prevent oversights.

3. Do you need to be a tax expert to make sure you don't miss anything?

Not at all, and that's precisely the point. taxx.lu asks straightforward questions about your circumstances and guides you through the process step by step. You don't need to know tax legislation by heart.

To make things even easier, the AutoScan feature allows you to upload certificates and supporting documents to pre-fill certain information. One word of advice, however: always check the imported information carefully and bear in mind that some foreign documents may not be recognised automatically.

As you complete your return, an estimate of your potential refund is displayed in real time. It's an estimate, not a guarantee, but it gives you a useful indication of how your return is progressing.

For those who would like extra reassurance, the Plus package includes a review of your tax return by a taxx.lu expert, while the Premium package also includes personalised telephone advice.

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4. You place great emphasis on planning ahead. Why does timing matter?

It's important to distinguish between two different timeframes.

For the current tax return, getting started early gives you time to gather your supporting documents, review your information and correct any errors before submission. The December rush is precisely what causes people to overlook valuable deductions.

For the following tax year, the importance of planning ahead are even more apparent. The Opti-Score feature provides personalised tax optimisation suggestions, but it's important to understand how it works: it's focused on the future. An action taken this year will affect next year's tax return, not the one you're currently completing.

That's why we say a good tax return starts long before the filing deadline. Setting up a pension savings plan at the beginning of the year, for example, allows you to make the most of the available tax advantages, especially with the deduction limit increasing to EUR 4.500 per person from 2026.

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Two good reasons to think about retirement from the start of your working life!

Completing studies: check. Finding the first job: check. Having a head full of plans reminds you that you have your whole life ahead of you to achieve them, because you’re young. However, this is precisely why we need to talk to you about your retirement. Retirement may still seem a long way away to you, but read this article to understand why now is the right time to think about it!

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5. Any final words for those who are still hesitating?

Completing your tax return doesn't have to be a chore that you put off until the last minute. The earlier you get started, the greater your peace of mind and the better your chances of ensuring nothing is overlooked.

And for Spuerkeess customers, there's an added benefit: by selecting Spuerkeess as your partner and providing your bank account details, you'll receive a 30% discount on taxx.lu packages.

In practical terms: