The Supporting Small Affordable Housing Developers Act provides tax breaks for small to mid-sized companies that develop or rehabilitate affordable housing. Specifically, the bill excludes from taxable income any grants these companies receive for affordable housing projects and any cash proceeds they earn from selling state or local tax credits related to housing development. The bill targets eligible businesses with gross receipts up to $36 million that work in construction, property management, or related housing industries. The tax benefits apply to taxable years beginning after the bill's enactment, with the $36 million threshold adjusted annually for inflation starting in 2028. Additionally, the bill allows these eligible developers to exclude from income any debt relief on loans used to finance affordable housing projects, though this benefit requires reduction of other tax attributes as compensation to the government.