LIHTC Qualified Census Tracts are defined by HUD in the following way:
- A census tract must have 50% of its households with incomes below 60% of the AMGI to be eligible. HUD has defined 60% of AMGI income as 120% of HUD's Very Low Income Limits, that are based on 50% of area median family income, adjusted for high cost and low income areas. The 1994 income estimates were then deflated to 1989 dollars, so they would match the 1990 Census income data.
- For each census tract, the percentage of households below the 60% income standard was determined by (a) calculating the average household size of the census tract, (b) applying the income standard after adjusting it to match the average household size, and (c) calculating the number of households with incomes below the income standard.
- Qualified Census Tracts are those in which 50% or more of the households are income eligible and the population of all census tracts that satisfy this criterion does not exceed 20% of the total population of the respective area.
- In areas where more than 20% of the population qualifies, census tracts are ordered from the highest percentage of eligible households to the lowest. Starting with the highest percentage, census tracts are included until the 20% limit is exceeded. If a census tract is excluded because it raises the percentage above 20%, then subsequent census tracts are considered to determine if a census tract with a smaller population could be included without exceeding the 20% limit.
Maps of Qualified Census Tracts (QCTs) and Difficult Development Areas (DDTs) are available on the official HUD site: