TLDR: To justify transport expenses for professional purposes, you must provide documents proving the professional use of the vehicle, the mileage covered, or the expenses incurred. Depending on your status (employee, self-employed, etc.), the required supporting documents vary: flat-rate scale, invoices, expense reports, employer certifications, or equivalent documents.
Supporting documents for actual expenses and the flat-rate scale
If you opt for the actual expenses regime or use the flat-rate scale, you must justify the professional mileage covered. This scale takes into account the vehicle's fiscal horsepower, its type of engine, and the annual distance traveled. Toll fees, garage costs, parking fees, and interest for vehicle purchase on credit are excluded from this assessment.
Case of employees with frequent travel
If you are an employee and regularly make business trips (e.g., sales representative), you are not required to provide detailed supporting documents for each expense. It is sufficient to present elements that allow the assessment of the importance of the main categories of expenses, such as:
- the regions visited;
- a sufficient number of hotel receipts to trace your tours;
- certifications from your employer regarding the conditions for visiting clients;
- the modes of transport used.
Professional services subject to VAT
For transport expenses related to professional services subject to VAT (e.g., services provided by lawyers or judicial officers), the supporting documents include invoices or expense reports issued by the service provider.
Carpooling
Travel expenses incurred by a passenger as part of carpooling (as defined by the transport code) are accepted as actual professional expenses if they are properly justified.
Treatment of home-to-work trips
For trips between your home and workplace, travel expenses are deductible up to the first 40 kilometers, even if the distance is greater. Beyond that, deduction is possible only if you justify the normal nature of the distance.
General obligations
Regardless of your situation, you must keep documents proving the reality of the expenses or trips. These supporting documents must be clear, precise, and appropriate to the nature of the expenses incurred.