IL SB3993

Extends the deadline for property owners to apply for reduced assessed value on affordable rental housing from December 31, 2027 to December 31, 2037.

Allows counties with less than 3,000,000 inhabitants to opt out of the special assessment programs through county board ordinance, with ability to rejoin later.

Requires a project labor agreement with local building trades council prior to construction for properties seeking reduced valuation under the 30-year low affordability community program.

Establishes two assessment reduction programs: one providing 25-35% reduction for 10 years if property maintains 15-35% affordable units, and another providing graduated reductions over 30 years (100% to 20%) for low affordability communities maintaining 20% affordable units.

Defines "qualifying rehabilitation" with minimum expenditure thresholds of $8, $12.50, or $60 per square foot depending on program tier, and specifies eligible improvements including electrical, heating, plumbing, roofing, windows, and energy conservation upgrades.