Answer
IRPF, which is often compared to personal income tax, is calculated under rules that depend on the type of income and tax status. A progressive system applies to employment income, so there is no single fixed rate for all cases.
Older guidance cites a range of 0 to 36% and gives examples of rates for different levels of monthly income. However, the actual calculation depends on current tax brackets, the relevant period, deductions, multiple employers, and other income. Employment income, capital income, rental income, and business income should not be combined in a single calculation.
Employers usually withhold income tax from salaries, but this does not always mean that no further obligations remain. A separate calculation may be required if you have several types of income, a change in status, or foreign payments. The calculation should be based not on a rate you have heard about, but on the classification of each type of income.