Business Taxation: Taxes, Deductions and Optimization

Corporate tax optimization rarely starts with a structuring scheme. It starts with three foundational decisions — the tax regime, the treatment of investments, and the rigor of supporting documentation — which determine most of the actual tax burden. The rest is a matter of marginal adjustments, often overestimated. This article covers these three areas, then the points where the tax authorities most frequently issue adjustments.

The Tax Regime, a Foundational Decision

Profits are taxed either under personal income tax in the hands of the operator or partners, or under corporate income tax at the level of the company itself.

The applicable regime depends on the legal form, but it is largely optional: a sole proprietorship or a partnership can elect to be subject to corporate income tax, and certain capital companies can, under conditions and for a limited period, elect the partnership tax regime.

The trade-off hinges on one concrete point: what the manager actually withdraws. Under personal income tax, the entire profit is taxed in the manager's hands, whether withdrawn or not. Under corporate income tax, undistributed profit is taxed only at the company level; compensation paid out is deductible from taxable income, and dividends are subject to their own tax regime. A company that reinvests generally finds it advantageous to be under corporate income tax; a business whose manager withdraws the entire profit does not automatically benefit from it.

Regarding rates, a reduced rate of 15% applies to a first bracket of profit, subject to conditions relating to revenue, the full payment of share capital, and its majority ownership by individuals. Beyond this bracket, the standard rate applies. Since these thresholds are periodically revised, they should be checked for the fiscal year in question.

Deductible Expenses: Four Cumulative Conditions

An expense is deductible only if it meets all of the following conditions:

• It is incurred in the interest of the business, and not in the manager's personal interest.
• It results in a decrease in net assets, which excludes expenditures that actually constitute a capital asset.
• It is recorded in the fiscal year in which it was incurred.
• It is substantiated by a valid supporting document.

The fourth condition is the one that causes the most deductions to be lost, and it is purely documentary. A genuine and perfectly legitimate expense becomes non-deductible for lack of a compliant invoice. This is also the area where the rollout of electronic invoicing is changing practices: the reliable audit trail, which links the invoice to the underlying transaction and to payment, is becoming the standard of proof. Our article on the reliable audit trail details what this requirement covers.

Certain expenses are excluded by nature, regardless of their usefulness: fines and penalties, lavish expenditures, and part of the costs related to passenger vehicles.

Investments: Depreciate, Provision, Deduct

Three treatments coexist and are not interchangeable.

Depreciation spreads the deduction of a capitalized asset over its useful life. The choice of method and duration is not free: it must reflect the actual consumption of the expected economic benefits. The applicable rules are covered in our article on accounting depreciation.

A provision anticipates a probable and clearly specified expense. Its deductibility requires that the event be ongoing at the close of the fiscal year and that the amount can be estimated with sufficient accuracy. A flat-rate provision, calculated as a percentage without individual analysis, is regularly rejected — see our rules applicable to provisions.

Immediate deduction remains possible for low-value assets, below a per-unit threshold, as well as for maintenance expenses that do not extend the asset's useful life. The line between deductible maintenance and improvements that must be capitalized is a classic point of tax adjustment.

VAT, a Cash-Flow Issue as Much as a Tax Issue

VAT is not an expense for the taxable business, but it weighs on its cash flow and accounts for a significant share of adjustments.

Deducting input VAT requires a compliant invoice containing all mandatory information, an expense incurred for the purposes of transactions giving rise to a right of deduction, and the tax having become chargeable at the supplier's level. Certain expenses are excluded from the right of deduction, notably those relating to passenger vehicles and certain lodging services.

A VAT credit can be refunded rather than carried forward, which usefully changes the cash-flow profile of companies in an investment phase. The procedures are described in our article on VAT credit adjustment and refund.

Incentive Schemes: To Be Assessed Before Committing

Research tax credit, innovation tax credit, apprenticeship aid, exemptions linked to geographic location: these schemes represent significant amounts, but their underlying logic is the same. They require documentation built up as you go, not reconstructed the year of an audit.

A research tax credit without a technical supporting file and without tracking of time spent per project is a fragile tax credit. The amount obtained and the amount retained after an audit are two different things, and the gap depends entirely on the quality of the file.

What an Audit Looks At

The standard statute-of-limitations period allows the tax authorities to adjust the three preceding fiscal years. The most frequent points of adjustment are stable from year to year:

• Unsubstantiated or insufficiently substantiated expenses.
• Confusion between personal and business assets, particularly regarding vehicles, travel expenses, and mixed-use premises.
• Insufficiently individualized provisions.
• Capitalizable expenditures recorded as expenses.
• VAT deducted on expenses excluded from the right of deduction.

Rights and obligations during the procedure — response deadlines, guarantees, avenues of appeal — are covered in our article on tax audits.

Usage Scenarios

Starting a business. The choice of tax regime should be made based on a three-year projection of the manager's withdrawals, not on the displayed tax rate alone. This is the decision with the greatest cumulative effect.

Unexpected profitable fiscal year. Legitimate year-end levers are limited: recognizing justified provisions, incurring genuinely useful expenses before the closing date, and verifying that depreciation has been properly applied. Decisions made after the closing date have no retroactive effect.

Significant investment. The trade-off between immediate deduction and depreciation should be planned before the commitment is made, since it depends on the nature of the asset rather than a discretionary choice.

Frequently Asked Questions

Which tax regime should be chosen? This mainly depends on what the manager actually withdraws. The corporate tax regime suits companies that reinvest, since undistributed profit is taxed only at the company level. Taxation at the partner level taxes the entire profit, whether withdrawn or not.

Is a business expense always deductible? No. It must be incurred in the interest of the business, decrease net assets, be recorded in the correct fiscal year, and be substantiated. Certain categories are excluded by nature, such as fines and lavish expenditures.

Can a vehicle be deducted? Partially. Passenger vehicles are subject to a cap on deductible depreciation and are excluded from the right to deduct VAT. Commercial vehicles follow a different regime.

Is a provision freely deductible? No. It requires a probable, clearly specified expense whose triggering event is ongoing at the close of the fiscal year. A flat-rate provision, calculated without a case-by-case analysis, is regularly challenged.

How many years back can the tax authorities go? The standard statute-of-limitations period covers the three preceding fiscal years, with extended periods in certain situations, notably in cases of undisclosed activity.

Is the research tax credit risky? The scheme itself is not; a file put together after the fact is. Technical documentation and time tracking by project must be produced as the work progresses so that the credit obtained can withstand an audit.

Key Takeaways

Three decisions determine a company's actual tax burden, and they are made upfront: the tax regime, decided based on the manager's actual withdrawals rather than the displayed rate; the treatment of investments, between immediate deduction, depreciation, and provisions; and the quality of supporting documentation.

This last point is the least glamorous and the most profitable. Most tax adjustments do not target questionable structuring schemes but genuine expenses that were poorly documented. Accounting records in which every entry is linked to a valid supporting document retain, after an audit, what approximate bookkeeping would only have declared.