How to calculate ISTAT revaluation and interest on value credits

The steps

1. 1.

   Identify the calculation base

   The first step is to identify the initial capital, known as 'sors'. If the judge or expert has liquidated the damage in current values, it must be devalued to the date the credit arose, which is the moment of the tort. Devaluation is achieved by dividing the current amount by the ISTAT coefficient corresponding to the period between the tort and the liquidation. This step is crucial because compensatory interest must be calculated on the original value of the asset, not on the already updated one.

2. 2.

   Retrieve updated ISTAT indices

   To perform the revaluation, you must use the consumer price index for blue- and white-collar worker households, known as the FOI index, excluding tobacco. The monthly updated values must be consulted exclusively on the official portal of the National Institute of Statistics or the Official Gazette. You need to note the index of the month the credit arose and the indices of the corresponding months for each subsequent year up to the date of liquidation or settlement.

3. 3.

   Apply year-by-year revaluation

   Revaluation is not calculated in a single final lump sum but must proceed in time brackets, typically annual. The original capital is multiplied by the ISTAT adjustment coefficient of the following year, obtaining the revalued capital for the first year. The following year, this new capital is taken and multiplied by the coefficient of the current year, and so on. This method creates a progressively increasing calculation base on which interest will then be computed.

4. 4.

   Calculate compensatory interest

   Following the teaching of the Joint Sections (Cass. 1712/1995), compensatory interest, aimed at compensating for loss of profit due to delay, is calculated neither on the original sum nor on the fully revalued one. Instead, it is calculated on the capital revalued year by year. For each annual fraction, the legal interest rate, or the one equitably established by the judge, is applied to the revalued capital of that year. The partial interest results of each year are then added together.

5. 5.

   Practical calculation example

   Let us assume a damage of 10,000 euros arising in January of year X. In January of year X+1, ISTAT inflation is 2%. The revalued capital becomes 10,200 euros. Legal interest, assuming 5%, for the first year is calculated on the initial 10,000 euros, generating 500 euros. For the second year, the 5% interest will be calculated on the 10,200 euros, generating 510 euros. At the end of the second year, the total due will be 10,200 euros of revalued capital plus 1,010 euros of accumulated interest, totaling 11,210 euros.

6. 6.

   Handling advances and partial payments

   If the debtor has paid an advance before the final liquidation, it must be correctly deducted to avoid errors. The advance must first be devalued to the date of the tort and then subtracted from the original capital. Alternatively, the original capital is revalued up to the date of the partial payment, the nominal advance paid is subtracted, and revaluation and interest calculation continue only on the residual capital. Both methods ensure compliance with the compensatory principle without duplication.

Legal basis: Cassazione Civile, Sezioni Unite, sentenza n. 1712 del 17 febbraio 1995Art. 1219 Codice Civile (Costituzione in mora)Art. 1224 Codice Civile (Danni nelle obbligazioni pecuniarie)Art. 2056 Codice Civile (Valutazione dei danni)