💡 A business use percentage must be defined for all types of vehicles: car, van, motorcycle, bicycle.
⚠️ Once the business use percentage has been applied to vehicle costs, the tax disallowance (based on fuel type and CO2 rate) still needs to be applied.
This applies to all vehicle-related costs: purchase or lease of the vehicle, fuel, maintenance, insurance, tyres, parking,...
Mixed private and professional expenses
Your vehicle is one of your mixed-use expenses: you use it both for your professional activity and for your private life. Only the professional portion can be included in your expenses as a self-employed sole proprietor.
You therefore need to define the business use percentage: the percentage of professional use relative to total use.
All costs related to your vehicle must be split in your accounts on the basis of this percentage.
Estimating your annual kilometres
1️⃣ Professional kilometres
👉 Examples of professional journeys:
Trips to clients or patients, to court, to a building site,...
Visits to your accountant or an accredited business counter
Trips to suppliers for purchases related to your activity
Professional training
Attendance at trade fairs or professional events
💡 Journeys from home to your place of work are considered private, unless they are not made directly.
For example: you stop at a building site or at court before going to your usual place of work ➡️ the journey is considered entirely professional.
2️⃣ Home-to-work kilometres
What is a place of work? It is a location you travel to at least 40 times a year (e.g. your office or practice).
Journeys from home to your place of work are not considered professional, but rather private. They are therefore not taken into account in the professional use percentage of your vehicle. However, they are deductible on a flat-rate basis at €0.15/km. Your accountant will apply this flat rate if you have home-to-work journeys.
💡 If you have included journeys to your place of work in your professional trips, with a stop at a client's, at court or on a building site for example ➡️ you should not include this journey in your home-to-work kilometres, since it is then considered professional.
This will increase the professional use percentage of your vehicle (but will reduce the €0.15/km flat rate for home-to-work journeys).
3️⃣ Total kilometres
You can use the total kilometres you travelled in the previous year, if you already had your car (and adjust it if your situation has changed).
Check that the total annual mileage is consistent, i.e. that it corresponds to the sum of the following kilometres:
Home-to-work journeys: see above
Professional journeys: see above
Private journeys: doing your shopping, taking your children to school or to their activities, going on holiday, visiting friends or doing activities at the weekend (if you have no idea how many private kilometres you travel, use 6,000 km/year).
Comparing professional kilometres to total kilometres
Once these figures have been estimated, the business use percentage is simply the professional kilometres relative to the total kilometres:
Business use percentage (%) = (professional km / total km) x 100
👉 I travel 10,000 km professionally, and 20,000 km in total over the year — what is my business use percentage? Business use percentage = 10,000 / 20,000 × 100 = 50%. That leaves 10,000 km for private journeys and home-to-work trips.
⚠️ Make sure this is consistent: if you estimated your home-to-work kilometres at 10,000 km, that would mean no private kilometres remain ➡️ you will therefore need to revise your professional kilometres downwards or your total mileage upwards.
💡 Be sure to check your estimates at the end of the year. A tax inspector could easily find out the actual mileage through maintenance invoices or the vehicle's technical inspection.
Taking your mobility needs into account
Beyond mileage, it is important to consider how your work is organised and how mobile your activity requires you to be:
Type of profession | Explanation | Suggested business use percentage |
Office-based | You work mainly from your practice, in a fixed office, or at a hospital | 0%, 25%, 50% |
Mobile | You regularly travel to clients, patients, building sites, courts, care homes, suppliers,... | 50%, 75%, 90% |
⚠️ If you deduct a large number of home-to-work kilometres on a flat-rate basis (€0.15/km), the business use percentage of your vehicle will generally be lower.
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