Be careful with your mixed-use expenses
When a professional expense has mixed use (partly professional and partly private), you only deduct the business use percentage of the expense.
Here are some tips on how to calculate it.
Car
Take the professional kilometres driven during the year divided by the total kilometres driven. Please note that home-to-work journeys are considered private use.
More details in this article: Defining the business use percentage of my vehicle
Smartphone, tablet and computer
It is difficult to estimate professional use. Therefore, use 75%, which is in line with the recoverable VAT on this type of equipment.
Telecom
As with multimedia equipment, deduct 75% of your phone and internet subscription if you are self-employed as your main activity, and 50% if you have a complementary business activity.
Office and building (at home)
Simply calculate the proportion between the professional floor area and the total floor area of the home, also applying a pro-rata share for shared spaces (for example, toilets).
In all cases, also pay your mixed-use expenses from your professional bank account. In the event of an audit, you will avoid having to provide your private bank statements to prove the expense. If your professional account does not have sufficient funds, you can simply make a transfer from your private account to your professional one.