Istat revaluation: bringing an amount up to date with the FOI index
Choose the amount, the starting month and the target month: the tool applies the FOI indices and the linking coefficients Istat prescribes.
In Italy, sums of money are brought up to date (rivalutazione) with one index: the consumer price index for blue- and white-collar households excluding tobacco, known as FOI senza tabacchi, published monthly by the statistics office Istat. It is the index behind rent updates, maintenance allowances and court-ordered revaluations. The latest value is for September 2026: 104.3 on the 2025 base, 4.0% up on a year earlier. The revaluation coefficient is the target month’s index divided by the starting month’s, multiplied by a linking coefficient for each change of base in between: 1.373 (1995 to 2010 base), 1.071 (2010 to 2015) and 1.214 (2015 to the new 2025 base used since January 2026). The result is rounded to three decimals. Istat’s own example: January 2009 to January 2026 gives a coefficient of 1.336, an increase of 33.6%. Rents use the same index, but often only 75% of its change.
Amount revalued to September 2026
€12,700.00
coefficient 1.270 · +27.0%
€10,000.00
| FOI index January 2016 | 99.7 (base 2015) |
| FOI index September 2026 | 104.3 (base 2025) |
| Base-linking coefficients | 1.214 |
| Increase | €2,700.00 |
| Revalued amount | €12,700.00 |
Assumptions
Istat method: ratio of the FOI indices excluding tobacco for the two months, times the base-linking coefficients (1.373 · 1.071 · 1.214), coefficient rounded to three decimals. Method and sources
Checked by Radif Partners · Editorial policy · Method and sources
€1,000 revalued to September 2026
| Starting month | FOI index | Base | Coefficient | Revalued |
|---|---|---|---|---|
| January 2010 | 136.0 | base 1995 | 1.369 | €1,369.00 |
| January 2015 | 106.5 | base 2010 | 1.273 | €1,273.00 |
| January 2020 | 102.7 | base 2015 | 1.233 | €1,233.00 |
| January 2023 | 118.3 | base 2015 | 1.070 | €1,070.00 |
| January 2025 | 120.9 | base 2015 | 1.047 | €1,047.00 |
The method in four steps
- Read the FOI excluding tobacco for the starting month and the target month, each on its own base.
- Divide the target index by the starting index.
- Multiply by one linking coefficient per change of base in the period.
- Round to three decimals, then multiply the amount by that coefficient.
Istat asks for the calculation to be done in one go, without intermediate rounding; the tool follows that rule and covers months from January 1996 onwards.
Where this is used
Annual rent updates use the twelve-month change of the same index, at 75% or 100% depending on the lease: see the Istat rent update. Child or spousal maintenance set by a court is usually adjusted to Istat indices from the month of the ruling: see the maintenance allowance update. For a debt or damages award, see monetary revaluation of a claim; the monthly series is in the FOI index.