The legal interest rate is the applicable rate, pursuant to art. 1284 of the Civil Code, for the measurement of the rate of the legal default interest on the sums due to creditors. Below is a summary table of the rate trend from 1990.

The calculation of the legal interest rate (initially determined with ordinary laws) from 1999 is established from year to year, pursuant to the first paragraph of art. 1284 of the Civil Code amended by art. 2 of the law of 23 December 1996, n. 662, according to the following: "The legal interest rate is determined at 5 per cent on an annual basis. The Minister of the Treasury, with his own decree published in the Official Gazette of the Italian Republic no later than 15 December of the year previous to the one to which the essay refers, it may annually modify the measure, on the basis of the average annual gross yield of hard government bonds not exceeding twelve months and taking into account the inflation rate recorded in the year. If by 15 December no new rate has been set, it remains unchanged for the following year. "

The legal interest rate is used to pay the so-called "pecuniary obligations" which are characterized precisely by the fact of having as their object a sum of money, in fact the judges in their sentences based on the legal rate in force establish the measure of interest as a compensatory function for the failure / late payment of the sum of money.