The short answer: 4.3% or 2.47%
Rents updated in October 2026 use the August figure, the latest published by the National Statistics Institute (INE):
- CPI (IPC) for August 2026: 4.3%.
- IRAV (the reference index for residential rents) for August 2026: 2.47%.
With a rent of 1,000 euros a month, the difference is clear: with the CPI it would go up to 1,043 euros; with the IRAV, to 1,024.70 euros. That is a difference of about 220 euros a year. Knowing which one applies to your contract is money.
Which index applies to your contract
It depends mainly on when it was signed and what the contract says:
- Main residence contracts signed before 26 May 2023: what was agreed applies, which is almost always the CPI.
- Contracts signed from 26 May 2023, with the Housing Act already in force: the IRAV works as a cap. If the contract says CPI, the lower of the two applies.
- If the contract says nothing about updating, the rent is not updated. The Urban Leases Act only allows an increase if it was expressly agreed.
This month, with the CPI well above the IRAV, using the wrong index means charging or paying almost double what you should.
What about the 2% cap?
It no longer exists. The Government approved it twice this year, in Royal Decree-law 8/2026 in March and in 26/2026 at the end of September, and Parliament struck down both. Since 2 October updates are again governed by the contract and the IRAV, as explained above.
If an update with the 2% cap was applied to you, or you applied one, while either of those decrees was in force, the outcome depends on the dates. We explain it in the article on the repealed rent decrees.
How to carry out the update correctly
The updated rent can only be demanded from the month after the landlord notifies the tenant in writing, stating the percentage applied. If the tenant requests it, the INE certificate must be attached (article 18 of the Urban Leases Act).
For the landlord, a badly notified update may delay the increase or mean having to refund it. For the tenant, checking the calculation takes five minutes, and any overpayment can be claimed back.
If you are unsure which index applies to you or about an increase that has already been applied, we review your contract in the first consultation, which is free.
Further reading: what still applies after the repealed rent decrees and what to check in your rental contract in Madrid.