The lump-sum tax on registered income is one of the available taxation options for sole proprietorships. Under this regime, the tax is calculated based on gross revenue, without deductions for expenditure. This form is particularly attractive for entrepreneurs operating with high margins, including self-employed professionals working under B2B arrangements.

In practice, however, determining the correct lump-sum tax rate can be challenging, as it depends on service classification under the Polish Classification of Goods and Services (PKWiU).