US HB4660

Requires the HUD Secretary to reclassify certain housing-related activities under NEPA to reduce environmental review burdens, including tenant-based rental assistance, supportive services, operating costs, homebuyer assistance, and affordable housing pre-development costs as "exempt activities"

Creates categorical exclusions for rehabilitation of 1-to-4 unit residential buildings, scattered site development of up to 4 dwelling units, and acquisition or disposition of existing structures retained for the same use

Establishes streamlined categorical exclusions for new construction of 5-15 dwelling units per site, office-to-residential conversions with up to 20% building size increase, infill projects on previously disturbed land of 5 acres or less, and voluntary buyouts of properties in floodways or disaster-impacted areas

Defines "infill project" as development within municipal limits on previously disturbed land of not more than 5 acres, substantially surrounded by existing development, that repurposes vacant or dilapidated parcels for residential or commercial use

Mandates annual reports to Congress for 5 years beginning 2 years after enactment, summarizing reductions in review times and administrative costs for affordable housing, with recommendations for future changes to categorical exclusions