Amends the Illinois Municipal Code. Provides that, beginning January 1, 2027, each municipality shall, by ordinance, authorize the development of accessory dwelling units. Provides that each municipality shall permit accessory dwelling units in all zoning districts that permit single-family dwellings without additional requirements for lot size, setbacks, aesthetic requirements, design review requirements, frontage, space limitations, or other controls beyond those required for single-family dwelling units without an accessory dwelling unit. Provides that a municipality is not required to allow more than one accessory dwelling unit for any single-family dwelling. Provides that accessory dwelling units may be constructed at the same time as the principal dwelling unit. Provides that no municipality shall: (A) require additional automobile parking spaces for a property with an accessory dwelling unit beyond the requirements for a single-family dwelling unit without an accessory dwelling unit; (B) require the establishment of a familial relationship between the occupants of an accessory dwelling unit and the occupants of a principal dwelling unit; or (C) establish a minimum or maximum limit on (i) square footage of an accessory dwelling unit or (ii) the number of bedrooms of an accessory dwelling unit. Limits home rule powers.