Taxation of self-employed activities is carried out by the owners or shareholders.
This means that these companies are declared as part of the private tax return and are taxed at the normal tax rates for natural persons.
division of private and business
Although this is a private tax return, company deductions can also be made based on company expenses. In addition to the usual business-related expenses, these include patents and R&D expenses that are related to the STAFF introduced from 2020 onwards.
Taxes on self-employment: accounting and deductions
Depending on the complexity of the company, it is worthwhile Tax advice to optimize deductions and a simple or to conduct commercial accountingIn any case, the Auxiliary Sheet A must be submitted correctly.

Overview of the legal basis: Tax dossier ESTV on the taxation of self-employed persons.