Rate-case process
Utility-filed rate cases with Commission suspension and evidentiary review
A utility initiates a general increase through a tariff filing. The ICC may suspend the tariff, take testimony, and enter an order. Fuel, gas supply, infrastructure, efficiency, transmission, and other approved riders can change between full reviews.
Read the official framework ↗Wholesale power market
State rules
Full base-rate reviews set the broad revenue and return framework. Recurring riders, clauses, and reconciliations can change narrower charges between those reviews. These are governing patterns, not filing-date forecasts.
Electric and gas service
Full base-rate review
Electric and gas · ICC rate-regulated investor-owned electric and natural-gas utilities
Case-specific; no fixed recurring interval
A utility files when it seeks a base-rate change. The Commission may suspend a proposed tariff and conduct a contested evidentiary review.
Rate period: Historic or future test year supported in the filing
Governing rule ↗Between full reviews
Natural gas
Purchased gas adjustment
Periodic tariff updates and reconciliation
Approved purchased-gas costs are recovered separately from base distribution rates and reconciled through Commission proceedings.
Governing source ↗Electric
Fuel and purchased-power adjustment
Recurring tariff updates and reconciliation
Eligible supply costs may be adjusted and reconciled separately from delivery base rates.
Governing source ↗Electric and gas
Approved infrastructure and grid riders
Utility-specific filing and reconciliation
Illinois utilities may use Commission-approved riders or multi-year grid plans for specified investments; scope and cadence depend on the utility and authorizing order.
Governing source ↗Current activity