The personal income tax is a tax obligation that falls on the natural person. It is a progressive tax, so that the autonomous pays the tax agency the amount proportional to 20% of the profit obtained in a quarter. In other words, the higher the income of the self-employed, the higher the amount to pay to the Treasury.
The monthly I.R.P.F. is paid on the 30th day of each month. And the quarterly I.R.P.F. days: April 20 (1st quarter), July 20 (2nd quarter), October 20 (3rd quarter) and January 30 (4th quarter).