Brazilian rent adjustment: the figure and the working.
The arithmetic is simple: chain the monthly variations of the index named in the lease and apply the factor to the rent. What is usually missing is the legal half — periodicity, a lease with no index named, and an amount charged that is not the one in the clause.
How the period is built: the calculation accumulates the index variations from the month of the last adjustment, inclusive, to the month before the new one — an August-to-August adjustment is twelve variations.
The number checks out. Does
the clause match what you pay?
An index swapped without agreement, an adjustment applied before twelve months are complete, and a rent well above the market are three different arguments under Law 8,245/91. Send your simulation on WhatsApp for an initial review. The adjustment rules in the wider context of a Brazilian lease — term, guarantee, renewal and termination — are gathered in our guide to Brazilian tenancy law.
The formula, the source of the index and the legal basis.
factor = (1 + v₁/100) × … × (1 + vₙ/100), where v is the monthly variation of the index. From that come accumulated (%) = (factor − 1) × 100 and new rent = current rent × factor.Price indices are not added up: twelve variations of 1% accumulate to 12.68%, not 12%.
Where the index comes from. On page load the tool queries the Central Bank time series system (SGS) at api.bcb.gov.br/dados/serie/bcdata.sgs.{code}/dados. The codes are the official SGS ones: 189 for the IGP-M, 190 for the IGP-DI, 188 for the INPC and 433 for the IPCA. On success, the result carries the label "Central Bank" and the month of the latest figure. On failure, it falls back to the table stored in the code, states that the index could not be confirmed at that moment, gives the date of the table and points to the Calculadora do Cidadão.
Periodicity: the twelve-month floor
Rent adjustment is not free in time. Article 2, § 1, of Law 10,192/2001 provides that any stipulation of adjustment or monetary correction with a periodicity of less than one year is null and void as a matter of law. For residential leases, the sole paragraph of art. 17 of Law 8,245/91 refers expressly to that regime. That is why the calculator counts the months and flags anything short of twelve.
When the lease names no index
Law 8,245/91 does not choose an index for the parties. Article 17 provides that the rent is freely agreed, while prohibiting three things: stating it in foreign currency, linking it to exchange rate variation, and linking it to the minimum wage. Article 18 completes the picture: the parties may, by agreement, set a new rent and insert or amend an adjustment clause. Without a clause, adjustment depends on agreement.
Indexation is not review: art. 19 and the three years
Indexation restores value by the variation of a price index; review brings the rent to the market price, up or down. Article 19 sets the timing of that second route: failing agreement, either party may, after three years of the lease or of the previously reached agreement, seek judicial review of the rent to adjust it to the market price. Three years of the lease or of the previous agreement — not of the last index adjustment. In purpose-built leases, art. 54-A, § 1, allows a waiver of the right of review for the duration of the lease.
When the amount charged is not the amount in the clause
Swapping the index, applying a different percentage or bringing the anniversary forward amend the contract and, under art. 18, require agreement. If the tenant wants to pay what it considers correct and the landlord refuses to accept, Law 8,245/91 provides the action for judicial deposit of rent and lease charges, governed by art. 67.
Common questions on rent adjustment.
How often can rent be adjusted in Brazil?
Once every twelve months at most. Article 2, § 1, of Law 10,192/2001 is explicit: any stipulation of adjustment or monetary correction with a periodicity of less than one year is null and void as a matter of law. A six-monthly clause therefore does not stand. For residential leases, the sole paragraph of art. 17 of Law 8,245/91 refers the criteria to that specific legislation.
What if the lease does not name an index?
Law 8,245/91 does not pick an index on the parties' behalf. Article 17 provides that the rent is freely agreed, while prohibiting it being stated in foreign currency or linked to exchange rate variation or to the minimum wage. Article 18 adds that the parties may, by agreement, set a new rent and insert or amend an adjustment clause. Without a clause, adjustment depends on agreement; failing that, art. 19 applies.
Does a negative accumulated index force the landlord to lower the rent?
Law 8,245/91 says nothing about a negative index: the answer lies in the lease clause. If the clause directs that the accumulated variation be applied with no floor, applying it literally to a negative figure reduces the rent. Many leases include an express floor — wording such as the rent shall not be reduced, or a negative variation shall be treated as zero. The calculator shows the negative result as it is.
The landlord applied a different index from the one in the lease. What now?
The amount due is the one that results from the clause agreed. Changing the index or the percentage amends the contract and, under art. 18, requires agreement. Where the tenant wishes to pay what it considers correct and the landlord refuses to accept it, Law 8,245/91 provides the action for judicial deposit of rent and lease charges, under art. 67.
What is the difference between indexation and a rent review action?
They are different things. Indexation restores the value by the variation of a price index, once a year, as the clause provides. A review action brings the rent to the market price: art. 19 of Law 8,245/91 provides that, failing agreement, either party may, after three years of the lease or of the previously reached agreement, seek judicial review of the rent. The three years run from the lease or the last agreement, not from the last index adjustment.
How much does it cost to challenge a rent adjustment?
Many cases are resolved with a written notice and a calculation schedule, without proceedings, and the cost is limited to legal fees. If a claim is filed, court fees on the value assigned to the claim are added, and a review action may require an expert appraisal of the market rent. Fees are presented in writing after the lease has been read.
Do you assist clients outside São Paulo?
The indices on this page are national and Law 8,245/91 is federal, so the calculation works for leases in any state. The firm is based on Avenida Paulista and works with clients elsewhere remotely, by video call and with digital documents; in distant jurisdictions the work may involve a local correspondent lawyer.
