Mayor de Blasio and Speaker Mark-Viverito's deal on citywide zoning stages sets the stage for intense consideration of more than a dozen local rezonings that have been projected.

Demetrius Freeman/Mayoral Photography Office

Mayor de Blasio and Speaker Mark-Viverito's deal on citywide zoning stages sets the stage for intense consideration of more than a dozen local rezonings that have been projected.

When Mayor de Blasio rolled out his housing plan in May of 2014, there was some frustration with the lack of specifics. His administration explained that the fine details couldn’t be discussed at the outset because they would grow out of the separate planning processes to take place in each of the 15 neighborhoods he was targeting.

The deal announced Monday on the mayor’s citywide Mandatory Inclusionary Housing and Zoning for Quality and Affordability proposals means the action now moves to those individual plans—and the decisions by individual councilmembers and developers that will shape the housing that actually gets built.

MIH and ZQA are both very big deals and their approval, expected next week, is a major win for de Blasio—especially since community boards took broad exception to both initiatives, suggesting a lack of support the mayor evidently worked around. New York City will now have the most aggressive mandatory inclusionary framework in the country. Back in early 2013, I heard Candidate de Blasio bemoan at a housing forum the fact that Mayor Bloomberg through his rezonings had traded away billions and billions of dollars in public assets (the value of the new developable space created by the zoning changes) for previous little in return from developers. With MIH, de Blasio is changing that calculus.

The concessions made to critics of his plan are also considerable, although they did not satisfy veryone. Creating an option for developers to meet MIH requirements by building fewer affordable units but making them affordable to families in lower-income groups—20 percent of apartments with rents that average to a level affordable to 40 percent AMI is now the low option, not 25 percent of units at 60 percent AMI—could make MIH units available to another 15 percent of the city’s population.

“Could” is the operative word there. The four MIH options will be for the Council to choose from as it considers each rezoning. Typically the Council defers to the member from the area being rezoned to take the lead on decisions like that—choosing whether to trade lower affordability for a smaller imprint, or vice versa. That won’t always be an easy choice.

Developers, meanwhile, will decide the precise mix of affordability levels to include in the stuff they build (as well as whether to build at all). MIH’s requirements are based around averaging, so a developer can build all her units at the required AMI, or build some for people higher up the income ladder and an equal number for those lower down.

MIH is, of course, only one tool. The de Blasio housing plan also will use subsidies to get affordable housing built beyond or in the absence of zoning requirements. There are tradeoffs there, too—deeper affordability can mean fewer units. Much depends on how the market develops in each neighborhood. A lot also depends on Albany figuring out how to replace 421-a, the tax subsidy that plays a critical role in the financial projections the city is using to map out its policy. Those projections, by the way, focused on AMIs of 50 percent and above, so the 40 percent level that advocates won is somewhat uncharted territory.

The local angle to the de Blasio plan will come to sharper relief soon when the Council votes on the East New York plan. Flushing West, Jerome Avenue and others will follow. The full list of neighborhoods is not yet public.