Managing business expenses well is one of the most powerful — and most legitimate — tax levers in Luxembourg. Whether you are self-employed, a majority manager or a company director, the quality of documentation and the consistency of the expenses incurred directly affect the amount of tax. Contrary to received wisdom, deduction is not complex: it rests on stable principles, provided they are applied methodically. This article sets out the rules, the most common categories and the pitfalls that cause a deduction to fail on inspection.
I. When does an expense become deductible?
Luxembourg tax law rests on a simple notion: only an expense incurred in the interest of the business can reduce the taxable result. Three conditions must be met: a direct link with the activity, a proper supporting document, and correct accounting recognition. For the self-employed, these expenses reduce the profit subject to income tax; in a company, only tax-recognised expenses enter into the computation of corporate income tax and municipal business tax. It is this requirement of a business purpose that explains why certain expenses, such as fines or private costs, are disallowed.
II. The most frequently admitted expenses
In practice, Luxembourg professionals mainly incur six broad categories of expense, each following a specific logic.
Premises and the home office
Expenses relating to the workplace — rent, energy, internet, maintenance — are admitted where they support the activity. For home working, only the area actually used for professional purposes may be taken into account, on a reasonable and documented pro rata basis.
Business vehicles
Fuel, maintenance, leasing or depreciation: costs relating to a vehicle used for the business are deductible. In the case of mixed use, the business portion must be isolated on the basis of consistent tracking or a prudent estimate.
Equipment and working tools
Computers, phones, software, web hosting, furniture and subscriptions are admitted where they are necessary for the activity. Durable assets are depreciated over several years, whereas current consumables are deducted immediately.
Training and professional dues
Any training intended to maintain or develop skills useful to the activity is deductible, as are dues paid to relevant professional bodies.
Business meals
Meals are admitted where they take place in a professional context: a client meeting, a negotiation, a commercial discussion. To secure the deduction, it is useful to note on the invoice the client’s name and the purpose of the meeting. Private invitations and manifestly excessive amounts remain excluded.
Fees and insurance
Accountant, lawyer, notary, consultant, professional liability insurance or legal protection: these expenses are among the easiest to justify and are admitted in full.
III. The manager’s status and its impact
The treatment of expenses also depends on the manager’s social-security status. A manager holding more than 25% of the capital is affiliated as self-employed: their social contributions are deductible in their personal return, but not at company level; if the company bears them, they must pass through a shareholder current account. Conversely, a minority or non-shareholding manager has employee status, and their remuneration as well as the corresponding employer contributions are fully deductible by the company. Where several partners hold equal stakes, it is the actual decision-making power, rather than the capital split alone, that serves as the criterion.
IV. What is never deductible
Some expenses are excluded on principle. The following table contrasts the expenses typically admitted with those systematically rejected.
| Generally deductible | Never deductible |
|---|---|
| Rent and running costs of business premises | Private and personal expenses |
| Useful equipment, software and subscriptions | Clothing not specific to the activity |
| Fees, insurance, training | Fines, penalties and late-payment interest |
| Documented business meals | Dividends (distribution of profit) |
| Depreciation and incorporation costs | Mixed expenses without clear justification |
V. Why rigour changes everything
An expense that is well prepared, properly documented and recorded in the right place constitutes a perfectly legitimate tax optimisation. A poorly justified expense, by contrast, may be added back on inspection and directly increase the tax due, sometimes with interest. Three habits make the difference: precise bookkeeping, systematic documentation and a clear separation between private life and business activity.
Conclusion
Deducting business expenses is neither a privilege nor a grey area: it is a regulated right that rewards method. But one must know the limits, tailor the treatment to the director’s status and build documentation that can withstand an inspection. At Ease Advisory, we structure your accounts, identify the genuinely deductible expenses and secure their justification, so that your optimisation remains solid on the day the tax authorities examine it. Unsure about a category of expense? Let’s talk.