Amends the Property Tax Code. Provides that, in counties with 3,000,000 or more inhabitants, taxpayers of income-producing property shall submit income and expense data annually to the chief county assessment officer on or before July 1 of each year. Provides that, in counties of fewer than 3,000,000 inhabitants, the county board may provide by ordinance or resolution that taxpayers of income-producing property shall submit income and expense data annually to the chief county assessment officer on or before March 31 of each year. Contains certain exceptions. Effective immediately.