The Keep Housing Affordable Act of 2024 modifies the federal low-income housing tax credit program to allow developers and property owners to extend the period during which their buildings must remain affordable to low-income residents. Currently, buildings must maintain affordability for 15 years, but this bill permits taxpayers to elect an extension of either 30 or 50 years after the initial compliance period ends, allowing them to claim additional tax credits for maintaining affordable housing longer. The bill affects housing developers, property owners, and investors who participate in the low-income housing tax credit program, ultimately benefiting low-income renters by incentivizing longer-term housing affordability. The legislation also provides an exception from certain bond volume caps to help finance the refinancing of extended affordable housing projects. The changes apply to buildings placed in service after the bill is enacted into law.