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.

Read our MHA summary to learn more: 

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What's Happening Now?

We published a draft environmental impact statement (EIS) on June 8, 2017. The public comment period is open until July 23. 

Draft zoning maps

In October 2016, we released draft maps for your input on the possible zoning changes needed to implement Mandatory Housing Affordability (MHA) in specific neighborhoods. We are taking 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. The comment period is open until July 23, 2017. Visit our draft EIS page to review and comment. 

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.

The City Council adopted legislation to implement MHA in Downtown and South Lake Union excluding Chinatown-International District on April 10, 2017, and will consider legislation for Chinatown-International District from April to June.

MHA implementation in Downtown and South Lake Union was originally proposed to be done as a single action but was later split into two pieces of legislation: one to implement MHA in Chinatown-International District and another to implement MHA in all other areas of Downtown and South Lake Union. Consequently, the Original Draft Proposal and SEPA Draft Proposal includes information on the entire area including Chinatown-International District. However, the legislation to implement MHA was submitted separately for Chinatown-International District and other areas. 

Legislation to implement MHA in Chinatown-International District Transmitted to the City Council (April 2017)

Legislation to implement MHA in Downtown and South Lake Union, excluding Chinatown-International District (adopted April 2017) 

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

  • Download the draft MHA zoning maps as PDFs.
  • The MHA areas map shows how MHA requirements vary geographically.

We've illustrated example buildings in various zones based on proposed MHA development standards and affordable housing requirements:

Draft MHA Urban Design and Neighborhood Character Study

We also have a draft urban design analysis that reviews common development examples in multifamily and commercial zones after MHA implementation. The development prototypes consider the design and scale of new development with the proposed MHA capacity increases. We summarize and discuss draft zoning standards. 

MHA Neighborhood Model Slideshow

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 Vinita.Goyal@seattle.gov.

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.

MHA Implementation

With approval from the Mayor and City Council, MHA is now in effect in the following neighborhoods: 

MHA Framework Legislation