This bill would establish a basement and cellar dwelling unit legalization program in certain community districts. Building owners would be able to apply for an authorization for temporary residence for units that existed prior to April 20, 2024. The Department of Buildings would inspect such units prior to issuing an authorization and, if issued, the building owner would be permitted to do any necessary construction on the unit to legalize the unit and apply for an amended or partial certificate of occupancy. The Department of Housing Preservation and Development would be required to provide technical assistance and outreach to owners of eligible basement or cellar residences. Tenants who resided in the basement or cellar unit on April 20, 2024 would have a right of first refusal to return to such unit upon its first occupancy following any necessary alterations.