By definition tax credit building are for individuals who "federal low-income housing tax credit program" or simply LIHTC, is a popular affordable housing program that has been around since 1987. Unlike most housing programs that are administered by HUD, the tax credit program is administered by the IRS, in coordination with state housing finance agencies across the country. Landlords who participate in the program get to claim tax credits for 10 years for their tax credit properties in return for renting at least some of their apartments to low-income tenants at a restricted rent.
The tax credit program gets its name because owners of participating properties receive valuable tax credits in return for keeping their buildings affordable. As a tenant in a tax credit property, the benefit you receive comes in the form of restricted rent, assuming you're income-eligible.