Mandatory Housing Affordability (MHA)

What is MHA?

Mandatory Housing Affordability (MHA) is a new policy to ensure that growth brings affordability. MHA will require new development to include affordable homes or contribute to a City fund for affordable housing. To put MHA into effect, we need to make zoning changes that add development capacity and expand housing choices. We accepted feedback on this draft proposal until June 30, 2017.

Read our MHA summary to learn more: 

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What's Happening Now?

The Draft EIS received a very high number of comments from community members and organizations. We now expect to publish the Final EIS in November 2017. The Final EIS will include a preferred alternative for MHA implementation; supplemental analysis on topics including racial equity and public school enrollment; and responses to the 800+ comments we received.

We published a Draft Environmental Impact Statement (EIS) on June 8, 2017. The public comment period closed August 7. We're now incorporating your feedback into the preferred alternative that we'll analyze in the Final Environmental Impact Statement. 

Draft zoning maps

In October 2016, we released draft maps for your input on zoning changes to implement Mandatory Housing Affordability (MHA) and expand housing options citywide. We took public input on the draft MHA proposal until June 30, 2017. 

Environmental Impact Statement

On June 8, 2017, we published a draft environmental impact statement (EIS) to evaluates a range of alternatives for implementing MHA and increasing housing choices.

Before developing the draft EIS, we held a public scoping period that closed in September 2016. In the Scoping Summary, we summarize the public comments we received with information on how we consider them in the EIS analysis.

Comprehensive Plan Amendments

Amendments to the City's Comprehensive Plan would be made in parallel with implementation of MHA in urban villages throughout the city. City Council considers Comprehensive Plan amendments once per year in an annual cycle. Review a description of the 2017-18 Comprehensive Plan amendments for MHA implementation, and visit our Comprehensive Plan page for more information.

MHA is now in effect in the following neighborhoods:

Legislative Documents

Chinatown-International District

Downtown and South Lake Union

SEPA Draft Proposal (May 2016)

Original Draft Proposal (November 2015)

MHA-Residential Framework (adopted August 2016)

MHA-Commercial Framework (adopted November 2015; amended December 2016)

Key Resources


MHA Draft zoning changes at (published October 2016)

MHA Draft zoning changes web map

Map of high, medium, and low MHA requirements

Draft MHA Urban Design and Neighborhood Character Study

This report provides urban design analysis of the potential zoning changes to implement MHA. We review a range of representative development prototypes in various multifamily and commercial zones. The prototypes consider the design and scale of new development with the draft MHA capacity increases. We summarize and discuss draft zoning standards. To comment on this report, email

MHA Affordable Housing Production Model Summary

This summarizes the approach and assumptions we used in our initial estimates of affordable housing production through MHA. The model's primary purpose was to inform policy discussions prior to MHA implementation. We also estimate growth and affordable housing production in our citywide MHA environmental impact statement.

MHA Economic Analysis

We have prepared an economic feasibility analysis to inform decisions about zoning changes to implement MHA. The analysis reviews a range of representative development prototypes in various multifamily and commercial zones. The prototypes consider the feasibility of new development with the proposed MHA affordable housing requirements and the proposed development capacity increases.