IL SB1521

Requires insurance companies to apply correct classifications, payrolls, and other rating system factors when computing workers' compensation premiums.

Mandates insurers refund excessive premiums paid when incorrect applications of classifications, payrolls, or other rating factors result in overpayment by an insured.

Requires insurers to pay 5% interest on excessive premiums from the policy inception date through the refund date, with the Director of Insurance authorized to award the interest.

Takes effect immediately upon becoming law.