Other types of risks to LIHTC stock: There are other risks to subsidized housing besides the risk of exiting a program when requirements expire that were not considered here, but that can affect all types of affordable housing (not just LIHTC). According to research by Abt Associates as well as Freddie Mac, the largest risk comes from depreciation since older properties are likely to need substantial reinvestment to remain habitable and financially viable. Also, properties that need ongoing federal support to lower operating expenses are subject to appropriations risk. If appropriations don't keep pace with costs, some developments may fail and take their units completely off the market.

Significant data limitations: The underlying HUD data has certain limitations, as documented by the National Low Income Housing Coalition and the Public and Affordable Housing Research Corporation (NLIHC/PAHRC). For example:

The information in the database is not updated annually. In particular, ownership status is set initially when the property is occupied and may not be updated to reflect changes from non-profit to for-profit. As a result, risk of individual properties becoming market rate may be underestimated.
It is unclear which properties may have exited the LIHTC program after 15 years as allowed using the Qualified Contract (QC) process.
The 30-year roll-off date may be an estimate, especially for older properties.
HUD’s database has a lag of two-three years from the in-service date to the availability of the information in the data set. The number of new units added in recent years may be underestimated as a result.
There is no data on tenant mix, which can change significantly once the compliance period ends.

Proximity to opportunity: This report focuses on the quantity of LIHTC units. An equally important consideration is the location of government subsidized housing and whether it is concentrating poverty in a few locations or opening up opportunity for historically disadvantaged populations to live throughout the region in mixed-income neighborhoods. Disadvantaged children who grow up in mixed-income neighborhoods and are able to establish cross-class friendships have been shown to have better life outcomes.

Impact on communities: This report does not consider the effect of LIHTC properties on the surrounding community, though most research suggests LIHTC units are a net positive, even in higher income areas.