Using your own car for your sole proprietorship? Here’s how the deduction of car expenses works

1. Car expenses in a sole proprietorship: two systems

A self-employed person in a sole proprietorship cannot grant themselves a fixed mileage allowance (€0.43/km, etc.). Car expenses are processed exclusively through:

1

1. the general expense lump sum, or

2

2. proving the actual costs

We explain both options so you can determine what is most beneficial in your situation.

Option 1: the general expense lump sum

If you choose the lump sum, you do not have to (and may not) prove any business expenses separately.

Everything is included in one legally determined percentage.

How does it work?

Professional income
→ lump sum = 30% of the profit
→ reduced by social contributions
→ maximum: €5,930

This lump sum includes all costs, including fuel, maintenance, insurance, depreciation of your car, etc.

Important: if you choose the lump sum, you cannot deduct car expenses separately. So no mileage allowance, no fuel invoices, no depreciation.

The lump sum is mainly interesting for starters or self-employed individuals with limited business expenses.

Option 2: proving the actual costs

If your sole proprietorship involves significant costs (such as car expenses, fuel, insurance, materials, etc.), it is usually better to choose the system of actual costs.

What do you need to keep?

• fuel receipts
• maintenance/repair invoices
• insurance and tax documents
• depreciation of the vehicle
• a mileage log to determine the business percentage

How do you calculate the deduction?

1

1. Add up all your car expenses for the year

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2. Determine what percentage of usage is business-related

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3. Deductible cost = total car expenses × business percentage

Example

Total car expenses: €5,000
Business use: 30%

You may deduct €1,500.

Important: The fixed mileage allowance only applies to reimbursements between employers/employees or company directors using their own vehicle. In a sole proprietorship, actual costs must be proven and the use of a fixed mileage allowance is not a legal option.

2. What about commuting?

Commuting expenses are fiscally limited in their deductibility.

As of 1 January 2026:

For commuting, the following applies:

• actual costs, or
• a lump sum of €0.15/km, but only for:
o vehicles with zero CO₂ emissions, or
o vehicles purchased/leased/rented before 1 July 2023

3. Mixed use (private + business)

Do you also use the car privately? Then you must determine the business usage percentage via:

• a mileage log, or
• a sample (usually a few representative months)

You apply this percentage to your total car expenses.

4. How do you record car expenses in your sole proprietorship?

You do not create an internal expense note with a mileage allowance—this system does not exist for sole proprietorships.

You process:

• receipts
• invoices
• insurance
• depreciation
• business usage percentage

In PIA Go!, you simply upload your supporting documents, and your dedicated accountant calculates the correct deduction.

5. What about a rental or lease car?

Here as well, you work with actual costs:

• leasing invoices
• fuel
• maintenance
• insurance
• taxes

The mileage allowance system does not apply.

PIA Go! keeps your car expenses clear

Car expenses are a maze of rules for many self-employed individuals.

With PIA Go!, you keep it simple:

• upload your invoices and receipts in the app
• your PIA Go! accountant calculates the correct business percentage
• you are certain that everything is handled correctly from a tax perspective

You work digitally, but never alone.