Creates the 340B Integrity Act. Defines terms. Provides that, beginning January 1, 2027, 340B covered entities shall not bill any medical assistance fee-for-service or medical assistance managed care programs under the Illinois Public Aid Code for 340B drugs. Provides that, beginning July 1, 2026 a 340B covered entity shall use 80% of 340B profits from the prior year to decrease at the point of sale, including at the 340B contract pharmacy, the out-of-pocket costs paid for 340B drugs that are dispensed or administered to low-income patients of the 340B covered entity. Provides that, on or before September 1, 2026, and on or before September 1 of each year thereafter, each 340B covered entity shall annually report to the Department of Insurance, with respect to the 340B covered entity and separately for each offsite outpatient facility associated with the 340B covered entity, the specified information about the prior year. Provides that, on or before December 31, 2026, the Department of Central Management Services shall submit a report to the General Assembly on any impact to the State employee health plan arising from 340B covered entity purchases, 340B contract pharmacy arrangements, and general practices related to 340B drugs, regardless of whether the 340B drugs were self-administered or provider-administered. Provides that the report shall include, but not be limited to, an analysis of foregone rebates, the impact on premiums, and the impact to State employee out-of-pocket costs. Provides that, on or before December 31, 2026, the Department of Healthcare and Family Services shall report to the General Assembly on certain items for total aggregated covered outpatient drug units dispensed or administered in the State for the prior calendar year in connection with the medical assistance program under the Illinois Public Aid Code, broken out by fee-for-service and by each managed care plan. Makes other changes. Effective immediately.