April 4 (Reuters) - Utility firm Duke Energy's Indiana unit said on Thursday it had filed for a base rate hike, asking to add nearly $492 million to its annual revenue with the state regulator Indiana Utility Regulatory Commission.

WHY IT'S IMPORTANT

Duke said the increase was for upgrading, maintaining and adding to its existing grid infrastructure, with over 60,000 new residential and business customers expected by next year.

The firm's Florida subsidiary also filed for a base rate increase earlier this week to increase efficiency, modernize the grid and invest in renewable energy.

BY THE NUMBERS

The rate increase, if approved, is expected to add nearly 16% on average to electricity bills, with a roughly 12% hike in 2025 followed by 4% in 2026, the company said.

A residential customer using 1,000 kWh a month would see an increase of $27.63, or about 19%, in their monthly bill.

A regulatory decision by the Indiana Utility Regulatory Commission is expected by early next year following public proceedings.

CONTEXT

Duke Energy Indiana last received approval for an increase in June 2020, according to the Indiana Office of Utility Consumer Counselor. As of last December, base rates comprised nearly 97.6% of residential bill for 1,000 kilowatt-hours (kWh) a month.

Utility companies use rate case proceedings with the respective regulators to address a revenue shortfall and ask for an increase in rates on the basis of the total cost of providing service.

(Reporting by Kabir Dweit in Bengaluru; Editing by Alan Barona)