0.82%. That was Brazil's official inflation rate in September, measured by the IPCA index from statistics agency IBGE, and anyone who paid a power bill at the end of the month felt the reason: residential electricity jumped 7.98% in 30 days. Over the past 12 months, prices are up 4.58%, above the 4.5% ceiling of the country's inflation target. It is the highest rate for a September since 2021, according to IBGE, which released the data on Friday (9).

In practical terms, a family that spent R$1,000 a month on the basket of goods and services tracked by IBGE now pays about R$1,046. A R$200 electricity bill in August came close to R$216 in September, just from the average adjustment. In September last year, monthly inflation had been 0.48%, almost half the current pace.

The result came in above expectations. The median forecast of financial market analysts was 0.76%, according to a Bloomberg survey cited by Folha de S.Paulo. From January to September, the IPCA is up 3.95%.

The power bill explains almost half of the month's inflation

September's main driver has a name: the end of the Itaipu Bonus, a temporary discount credited to August electricity bills that had pushed the IPCA into a 0.32% deflation that month. Without the benefit, power costs weighed heavily again. According to IBGE, electricity alone accounted for 0.32 percentage point of the index; without it, September inflation would have been 0.52%.

Also weighing were the yellow tariff flag, a surcharge of R$1.885 per 100 kWh consumed, and rate hikes in the cities of Belém, São Luís and Vitória. The Housing group, which includes electricity, rose 2.31%, the biggest increase among the nine groups surveyed.

Understand: what the inflation target ceiling means

Brazil runs an inflation targeting system: the National Monetary Council sets a 3% annual center, with a tolerance band of 1.5 percentage points either way. Breaching 4.5%, as now, does not mean an immediate miss. Under current rules, the target is only formally missed if inflation stays outside the band for six straight months.

It was not just electricity. Transportation rose 0.89%, with airfares 9.66% more expensive and gasoline up 1.21%. Food prices returned to inflation (0.83%) after three months of decline: tomatoes soared 37.76%, potatoes rose 24.07% and onions 10.14%, according to IBGE. All nine groups of goods and services increased in September.