an Austin, Texas city program to encourage more and higher-density affordable housing by offering a density bonus to projects in which at least half of units are reserved for lower-income households. It also allows units per lot to increase to 1.5 times the base zoning, or 6 units, whichever is higher.

Eligibility highlights:
- Half of units reserved for 60% MFI (rental) or 80% MFI (ownership)
- 25% of Affordable units 2BR or more.

Density bonuses:
- 25% additional height
- FAR waived
- Unit cap raised to 1.5X base zoning or 6 units, whichever is greater
- "Compatibility" restrictions limiting height near single family houses waived - Front and rear setbacks halved

plus 20% of rentals (so two in a sixplex, one in a fiveplex) need to be at 50% MFI or below. the affordability covenant is 40 years for rentals, 99 years for ownership

Summary from Curbed Austin:

"Affordability Unlocked, the density bonus program proposed by District 4 representative Greg Casar, aims to cut through barriers in the city’s land development code that can make building of affordable and multifamily housing difficult, if not impossible, by waiving many requirements as well as granting incentives in exchange fo building housing that meets the program’s criteria.

As a baseline, 50 percent of housing in a development must be affordable. That means rentals must be priced for families earning 60 percent or less of median family income for the area, with some required at 50 percent of MFI.

Home-buying prices must be affordable at 80 percent of MFI and below. If their projects meet baseline criteria, those offering deeper affordability could earn additional site privileges (essentially amounting to bonuses that increase density and thus total rentable or sellable space), including height increases above a zoning district’s current limits.

The program is applicable in commercial and residential zoning districts (except in industrial zones and without waiving rules regarding residential uses near health hazards) and in most special-use zoning and overlay districts.

Other loosened restrictions in developments that meet basic requirements include the reduction of setbacks and minimum lot sizes, waiving compatibility standards related to heigh and setbacks, and bringing accessible-parking requirements up to current code. Impervious-cover requirements are not waived under any scenario.

Qualifying rental units must remain at affordable rates as described in the ordinance for a minimum of 40 years and owner-occupied units for at least 99 years."

References

Austin, City of. "RESOLUTION NO. 20190221-027" [Affordability Unlocked program]. Introduced at City Council on February 21, 2019; approved on May 9, 2019. http://www.austintexas.gov/edims/document.cfm?id=315714.
Widner, Cindy. "Did Austin just unlock affordability? City Council approves plan to increase construction of lower-cost homes." Curbed Austin May 13, 2019. https://austin.curbed.com/2019/5/13/18618370/affordable-housing-austin-density-zoning-plan.