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Council approves Mosqueda legislation outlawing rent price fixing in King County, becoming 11th jurisdiction in nation to regulate such collusion

September 23, 2025

The King County Council on Tuesday unanimously passed legislation sponsored by Councilmember Teresa Mosqueda to prohibit large corporate landlords from using algorithmic rent price fixing platforms, like RealPage, to set and scale up the cost of rental housing in unincorporated King County.

Following the passage of similar legislation at the City of Seattle this July, King County now becomes the 11th jurisdiction across the country to prohibit collusion that is facilitated by these behind-the-scenes algorithmic tools. These platforms, like RealPage, are used by large corporate landlords to collude on rental prices, and legislation like this helps protect tenants from skyrocketing rent increases driven by these algorithmic price-fixing tools and prevent unfair practices from worsening King County’s housing affordability crisis.

“Algorithmic technologies are being used by large corporate landlords in communities across the country to artificially inflate rents. At the local level we must use all tools to stop this practice—capitalizing on our housing crisis, exacerbating displacement pressures, and making it harder for renters to get by is just plain wrong,” Mosqueda said. “As we work to create more abundant housing options for our communities, this legislation will ensure workers and renters are protected against these unfair practices in King County. I'm excited to join 10 other jurisdictions around the country regulating this type of collusion that is impacting local housing markets.”

The legislation is aimed at stopping algorithmic rent setting on platforms overwhelmingly used by large corporate landlords. It will not impact legal practices by local mom-and-pop landlords, as they tend to set their rents based on their own costs and communities, not these algorithmic price-fixing tools.

Click here to watch the robust committee discussion (starting at 18:00) on this legislation prior to today’s full council action.

What folks are saying:

Seattle City Councilmember Dan Strauss (District 6): “We’re in an affordable housing crisis. It’s absolutely unacceptable to allow landlords and tech companies use algorithmic rental price fixing software to artificially increase rent costs and vacancy rates. That’s why I was proud to cosponsor the City of Seattle’s legislation to ban that practice earlier this year. I applaud Councilmember Mosqueda’s leadership on this issue and fully support her legislation to do the same at the county level.

Seattle City Councilmember Alexis Mercedes Rinck (District 8, Citywide): “Thanks to Councilmember Teresa Mosqueda’s leadership King County will now be joining Seattle in banning the use of harmful rent fixing software. This is an important step in addressing housing affordability.”

King County Councilmember De’Sean Quinn (District 5): “For the everyday person, sitting down at the kitchen table figuring out how they are going to get through the day, whose only option is to pay what people say they need to pay, it’s important that we as a council are able to step in and ensure that basic human needs are not run on a for-profit system. Algorithmic rent software replicates inequity in the rental market locking out vulnerable tenants and raising costs unfairly serving as a tool for digital redlining.”

Kate Rubin, Co-Executive Director, Be:Seattle: “Landlords using algorithmic rent pricing have been colluding to drive up rents, not based on what is reasonable, but based on how much profit they can squeeze out of renters when they work in lockstep. This practice is inflating rents and fueling the region’s housing and homelessness crisis. This bill will protect renters from these exploitative tactics and help create greater housing stability across unincorporated King County."

Hali Willis, Community Policy Manager, Seattle/King County Coalition on Homelessness: “This legislation will prevent landlords from illegally colluding to fix rental prices in our region, where high housing costs exceed what most renters can afford. As King County sees record numbers of households lose their housing through evictions, we need a strategic and comprehensive approach that helps tenants afford their rents, prevents rent gouging, and reduces the number of households who experience housing instability or become homeless.”

How algorithmic rent-fixing works:

  • Data pooling: Companies collect information from multiple landlords — including rental prices, price changes, occupancy rates, and lease renewal dates.
  • Algorithmic recommendations: That data is processed with automated software to generate rent and lease recommendations for multiple landlords.
  • Reduced competition: Instead of competing on price, landlords are incentivized to follow the same recommendations, artificially driving up rents.

Key provisions of the ordinance include:

  • Bans collusion among landlords to set rental prices.
  • Prohibits landlords from contracting with rent-setting services that use algorithms to coordinate pricing.
  • Creates accountability: Renters harmed by violations can sue for up to $7,500 per violation, plus actual damages and attorney’s fees.
  • Directs the County Executive to prepare an enforcement study, due July 15, 2026, to identify the most effective options for monitoring and enforcement.

 

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